Advanced Process Manager

Control Functions and

Algorithms

AP09-600
 Implementation
Advanced Process Manager - 1

Advanced Process Manager

Control Functions and
Algorithms
AP09-600
Release 650
12/03
 Notices and Trademarks
© Copyright 2002 and 2003 by Honeywell Inc.

Revision 05 – December 5, 2003

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In no event is Honeywell liable to anyone for any indirect, special or consequential

damages. The information and specifications in this document are subject to change
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Other brand or product names are trademarks of their respective owners.

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 About This Publication
This publication supports TotalPlant® Solution (TPS) system network Release 640.
TPS is the evolution of TDC 3000X.

This publication defines the Advanced Process Manager I/O and control functions that
are available in software Releases 500 - 600. Used as a reference manual for process
engineers, control-system engineers, and application engineers who design and
implement data-acquisition and control strategies for TPS systems with Local Control
Networks and Universal Control Networks.

The user should be familiar with the system control functions described in System
Control Functions in the Implementation/Startup & Reconfiguration - 2 binder before
using this publication.

Detailed descriptions of the parameters mentioned in this publication can be found in the
Advanced Process Manager Parameters Reference Dictionary.

APM Control Functions & Algorithms 12/03

APM Control Functions & Algorithms 12/03
 Table of Contents

1 INTRODUCTION
1.1 General Description
1.1.1 I/O Functions
1.1.2 Control Functions
1.2 Common Functions
1.2.1 Point Form
1.2.2 Associated Display
1.3 Alarming
1.3.1 Alarm Priorities
1.3.2 Alarm Enable Status
1.3.3 Contact Cutout
1.3.4 Primary Module Point
1.3.5 Auxiliary Units
1.4 Red Tagging
1.5 References
2 I/O FUNCTIONS
2.1 Overview
2.2 High and Low Level Analog Input Point
2.2.1 PV Characterization
2.2.2 PV Range Checking and Filtering
2.2.3 PV Source Selection
2.2.4 Alarming
2.2.4.1 Disable Input Alarming When Using Open-Line Detection
2.3 Smart Transmitter Interface Point
2.3.1 Parameter Comparisons
2.3.2 STI IOP Functions
2.3.3 Smart Transmitter Communication Modes
2.3.4 Database Considerations
2.3.5 Point States
2.3.6 STI IOP Commands
2.4 Analog Output Point
2.4.1 Direct/Reverse Output
2.4.2 Output Characterization
2.4.3 Calibration Compensation
2.4.4 Disable Output Alarming when Using Open-Line Detection
2.5 Digital Input Point
2.5.1 Status Digital Input Point
2.5.2 Latched Digital Input Point
2.5.3 Accumulation Digital Input Point
2.5.4 Sequence Of Events Digital Input IOP
2.6 Digital Output Point
2.6.1 Pulse Width Modulated (PWM) Output Type
2.6.2 Status Output Type
2.6.3 Initialization Request Flag
2.7 Pulse Input Point
2.7.1 Operation
2.8 Serial Interface
2.8.1 Operation
2.8.2 Configuration
2.8.3 Checkpointing and Startup

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2.9 Serial Device Interface

2.9.1 Serial Device Interface Description
2.9.2 Manual/Auto Station Interface
2.9.3 Toledo Weigh Scale Interface

3 CONTROL FUNCTIONS OVERVIEW

3.1 Control Performance

3.1.1 Control Slot Types
3.1.2 Scan Frequency
3.1.3 Determining Processing and Memory Capacity
3.1.4 Performance Monitoring
3.2 Database Considerations
3.3 Point Execution State
3.3.1 Run-Idle-Run Transition
3.3.2 Warm Cold Restart
3.4 Peer-to-Peer Communication
3.4.1 Implementation
3.4.2 Restrictions
3.5 Hardware Reference Addressing
3.5.1 Find Names Function
3.6 Redundancy
3.7 Point Reservation
3.8 Status Messages

4 DIGITAL COMPOSITE POINT

4.1 Description
4.2 Point States
4.2.1 Normal States
4.2.2 Momentary States
4.2.3 Moving/Bad States
4.3 Mode Attributes
4.4 Interlocks
4.4.1 Permissive Interlocks
4.4.2 Override Interlocks
4.4.3 Configurable Interlock Bypass
4.4.4 Safety Interlocks for State 0 (SI0)
4.5 Commanded State (OP)
4.6 Digital Outputs
4.6.1 Latched Output
4.6.2 Pulsed Output
4.7 Output Connections
4.7.1 Digital Output Point—Latched Output
4.7.2 Digital Output Point—Pulsed Output
4.7.3 Logic Slot Flags
4.7.4 APM Box PV Flags

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4.7.5 Device Control Slot Flags

4.7.6 Array Point Flags
4.8 Read-Back Check
4.9 Initialization Manual
4.10 Digital Inputs
4.11 Input Connections
4.11.1 Digital Input Point—PV
4.11.2 Logic Slot Output
4.11.3 Logic Slot Flags
4.11.4 APM Box PV Flags
4.11.5 Device Control Slot Flags
4.11.6 Array Point Flags
4.11.7 Process Module Slot Flags
4.12 Current Input State (PV)
4.13 PV Source
4.13.1 PV Source Option
4.14 Alarming
4.14.1 Command Disagree, Command Fail, and Uncommanded Change
4.14.2 Off-Normal
4.15 Change-of-State Events
4.16 Local Manual Indication
4.17 Maintenance Statistics
4.17.1 Reset and Redtag

5 LOGIC POINT

5.1 Functions
5.2 Configuring the Logic Point
5.2.1 Logic Input Connections
5.2.2 Flags
5.2.3 Numerics
5.2.4 Logic Blocks
5.2.5 Output Connections
5.2.6 Generic Descriptors
5.3 Logic Block Algorithms
5.3.1 Null (Null)
5.3.2 AND Gate (AND)
5.3.3 OR Gate (OR)
5.3.4 NOT Gate (NOT)
5.3.5 NAND Gate (NAND)
5.3.6 NOR Gate (NOR)
5.3.7 XOR Gate (XOR)
5.3.8 Qualified OR Gate with 2 Inputs ON (QOR2)
5.3.9 Qualified OR Gate with 3 Inputs ON (QOR3)
5.3.10 Switch (SWITCH)
5.3.11 Compare Equal with Deadband (CE)
5.3.12 Compare Not Equal with Deadband (NE)
5.3.13 Compare Greater Than with Deadband (GT)
5.3.14 Compare Greater Than or Equal with Deadband (GE)
5.3.15 Compare Less Than with Deadband (LT)

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5.3.16 Compare Less Than or Equal with Deadband (LE)

5.3.17 Check for Bad (CHECKBAD)
5.3.18 Fixed-Size Pulse (PULSE)
5.3.19 Pulse with Maximum Time Limit (MAXPULSE)
5.3.20 Pulse with Minimum Time Limit (MINPULSE)
5.3.21 Delay (DELAY)
5.3.22 On Delay (ONDLY)
5.3.23 Off Delay (OFFDLY)
5.3.24 Watchdog Timer (WATCHDOG)
5.3.25 Flip-Flop (FLIPFLOP)
5.3.26 Change Detect (CHDETECT)
5.4 Logic Block Alarms
5.4.1 Configurable Alarms

6 PROCESS MODULE DATA POINTS

6.1 Purpose of the Process Module Data Point

6.1.1 CL/APM Sequence Program
6.1.2 Sequence Program/Unit Partitioning
6.1.3 Writing the Sequence Programs
6.1.4 Sequence Program Structure
6.1.5 Sequence Execution
6.1.6 Process Module Operating State
6.1.7 Sequence Execution Mode
6.1.8 Sequence Execution State
6.1.9 Sequence Overrides
6.1.10 Sequence Alarms
6.1.11 Sequence Messages
6.1.12 Restart Option

7 REGULATORY PV POINT

7.1 Features
7.2 PV Input Connections
7.3 PV Algorithm Calculation
7.4 PV Range Check and Filtering
7.4.1 PV Value Status
7.5 PV Source Selection
7.6 PV Alarm Detection
7.7 PV Algorithms
7.7.1 Data Acquisition (DATAACQ)
7.7.2 Flow Compensation (FLOWCOMP)
7.7.3 Middle of Three Selector (MIDOF3)
7.7.4 High Selector, Low Selector, Average (HILOAVG)
7.7.5 Summer (SUMMER)
7.7.6 Variable Dead Time with Lead-Lag Compensation (VDTLDLG)
7.7.7 Totalizer (TOTALIZR)
7.7.8 General Linearization (GENLIN)
7.7.9 Calculator (CALCULTR)

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8 REGULATORY CONTROL POINT

8.1 Functions
8.2 Control Input Connections
8.3 PV Source Selection (Pid, PosProp, and RatioCtl Algorithms)
8.4 Modes
8.4.1 Mode Attribute
8.4.2 Normal Mode
8.4.3 Normal Mode Attribute
8.4.4 Remote Cascade Handling (Pid Algorithms)
8.5 Safety Shutdown
8.6 External Mode Switching
8.7 Setpoint Handling
8.7.1 Setpoint (SP) Limits (Pid, PosProp, PidPosPr, and RatioCtl
Algorithms)
8.7.2 SP Target-Value Processing (Pid, PosProp PidPosPr, and RatioCtl
Algorithms)
8.7.3 PV Tracking (Pid Algorithms)
8.7.4 Deviation and Advisory Deviation Alarming
8.7.5 Bad Output Alarm
8.7.6 Ratio and Bias Options (Pid Algorithms)
8.7.7 SP Access Restrictions
8.8 Setpoint/Output (SP/OP) Tolerance Check
8.9 Alarm Detection
8.10 Control Output Processing
8.10.1 Initial Control Processing
8.10.2 Output High and Low Limits
8.10.3 Output Rate-of-Change Limits
8.10.4 Output Minimum-Change Limit
8.10.5 Output Limiting in Manual Mode
8.10.6 Control Output Connections
8.11 Initialization
8.11.1 PV Initialization
8.11.2 Control Initialization
8.12 Windup Protection
8.12.1 Windup Status
8.12.2 Status Propagation
8.13 Override Control
8.13.1 O/R Status and Feedback
8.13.2 Processing in an Override Control Strategy
8.13.3 Guidelines for Using Override Control
8.14 Control Algorithms
8.14.1 Proportional, Integral, Derivative (PID)
8.14.2 PID with Feedforward (PIDFF)
8.14.3 PID with External Reset-Feedback (PIDERFB)
8.14.4 Position Proportional Controller (POSPROP)
8.14.5 PID Position Proportional Controller (PIDPOSPR)
8.14.6 Ratio Control (RATIOCTL)
8.14.7 Ramp and Soak (RAMPSOAK)
8.14.8 Auto Manual (AUTOMAN)

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8.14.9 Incremental Summer (INCRSUM)

8.14.10 Switch (SWITCH)
8.14.11 Override Selector (ORSEL)

9 APM BOX FLAG, NUMERIC, STRING, TIME, AND TIMER GLOBAL

VARIABLES

9.1 Global Variables

9.2 Box Flag Data Point
9.2.1 Alarming
9.3 Box Numeric Data Point
9.4 Box Timer Data Point
9.5 Box Time Variables
9.6 Box String Variables

10 ARRAY POINTS

10.1 Array Point Overview

10.1.1 Node Specific Configuration Requirements
10.1.2 Array Parameter Names
10.2 Array Point Use with APM Box Global Variables
10.2.1 Configuration
10.2.2 Array Point Example
10.3 Serial Interface to Array Point
10.3.1 Accessing SI Array Data
10.3.2 SI Array Point Configuration
10.3.3 Status and Error Checking
10.3.4 Read-Back Check for Device Control/Digital Composite Points
10.3.5 CL Notes

11 DEVICE CONTROL POINT

11.1 Features
11.2 General Description
11.3 Input Connections
11.3.1 Digital Inputs
11.3.2 Logic Inputs
11.3.3 Secondary Variable Input
11.3.4 Local Manual Input
11.4 Output Connections
11.4.1 Digital Outputs
11.4.2 Logic Output Connections
11.5 Alarms
11.6 Maintenance Statistics

APM Control Functions & Algorithms vi 12/03

 1

INTRODUCTION
Section 1

This section contains an introduction to the Advanced Process Manager Control functions, and also
provides references to other publications that are useful or necessary in implementing control
system functions.

1.1 GENERAL DESCRIPTION

The Advanced Process Manager (APM) is designed to provide flexible and powerful
process scanning and control capabilities. To do this, it uses a powerful multiprocessor
architecture with separate microprocessors dedicated to perform specific tasks. As depicted
in Figure 1-1, the APM consists of the Advanced Process Manager Module (APMM) and
the I/O Subsystem.

The APMM consists of a Communication Processor and Modem, I/O Link Interface
Processor, and Control Processor. APMM redundancy can be optionally provided. The
Communication Processor is optimized to provide high performance network
communications, handling such functions as network data access and peer-to-peer
communications. The Control Processor is the APM resource dedicated to executing
regulatory, logic, and sequence functions, including a powerful user programming facility.
Because communication and I/O processing are performed by separate dedicated hardware,
the full power of the control processor can be applied to control strategy implementation.
The I/O Link Interface Processor is the interface to the I/O Subsystem.

The I/O Subsystem consists of a redundant I/O Link and the I/O Processors. These I/O
Processors handle all field I/O for both data acquisition and control functions. The I/O
Processors, for example, provide such functions as engineering unit conversion and alarm
limit checking independent of the APMM. All control operations are performed within the
APMM, with all data acquisition being performed in I/O Processors. The process engineer
has complete flexibility of choice, within the maximum APM design limits, in the
assignment of point types and control strategies. The interactive tools provided by both the
TotalPlant Solution (TPS) System Universal Station and Universal Work Station are used
to implement these selections. Refer to Section 31 in the Engineer’s Reference Manual for
more information.

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 1.1

NETWORK
INTERFACE
MODULE

ADVANCED PROCESS MANAGER

ADVANCED PROCESS MANAGER MODULE

Communication Processor I/O Link Interface Processor Control Processor

Universal Control Network
and Modem
UCN Network Support High Speed I/O Access Regulatory Control
Network Access to APM Data for Communications & Interlock Logic
Peer-to-Peer Communication Control Functions Sequence
Network Redundancy User Programming
APMM Redundancy Control
APM Config. Data Owner
Event Collection & Dist.

I/O SUBSYSTEM I/O LINK

Optional
HIGH LEVEL LOW LEVEL DIGITAL DIGITAL Fiber
ANALOG ANALOG INPUT INPUT Optics
INPUT INPUT PROCESSOR Sequence Of Extender
PROCESSOR PROCESSOR Events
Processor to Remote
16 8 32 32 IOPs

LOW LEVEL SMART SERIAL ANALOG

MULTI- TRANSMITTE INTERFACE OUTPUT
PLEXER R INPUT PROCESSOR PROCESSOR
PROCESSOR
32 16 32 8, 16

PULSE INPUT DIGITAL

PROCESSOR OUTPUT
PROCESSOR

8 16, 32

To Other APMs, HPMs, PMs, LMs, or SMs

15012

Figure 1-1 — APM Architecture

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 1.1.1

1.1.1 I/O Functions

The I/O Processors, in conjunction with Field Termination Assemblies (FTAs), perform
input and output scanning, and processing on all field I/O. A redundant I/O Link is standard
for added security. I/O processing is performed separately from control processing functions
so that I/O scan rates are completely independent of I/O quantity, controller loading,
processing, and alarming. This partitioning of processing requirements allows more
efficient use of control processor capability and future integration of additional I/O
Processor types.

The following I/O Processors (IOPs) are available for the APM:

• Analog Input—High Level (16 points)

• Analog Input—Low Level (8 points)

• Analog Output (8 points)

• Analog Output (16 points)

• Digital Input (32 points)

• Digital Input Sequence Of Events (32 points)

• Digital Output (16 points)

• Digital Output (32 points)

• Low Level Multiplexer (32 points)

• Pulse Input (8 points)

• Smart Transmitter Interface (16 points)

• Serial Interface (32 points)

• Serial Device Interface (16 points), (not shown in Figure 1-1)

Up to 40 of the above I/O processors can be selected in any mix. An option allows
redundant Analog Output and High Level Analog Input processors (up to 40 primary and 40
redundant IOPs). Each of the I/O processor functions is described in Section 2.

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 1.1.2
1.1.2 Control Functions

The APM provides a variety of control tools that can be customized to address a wide range
of process automation needs. Functions from I/O scanning, through regulatory and logic
control to more advanced control can be easily implemented through the APM. The APM
toolbox includes a sophisticated regulatory control package, fully integrated interlock logic
functions, and an advanced process engineer-oriented Control Language (CL/APM).
CL/APM is an enhanced version of the Control Language implemented by Honeywell in the
Multifunction Controller, Process Manager, and Application Module. This language facility
includes the sequence structures needed to handle batch or hybrid applications as well as the
computational capability needed for some continuous control tasks. Key to the power of this
control capability is that each of the functions shares data freely within the APM and can
share data from other devices on the Universal Control Network.

The following point types reside in the APMM:

• Regulatory PV • Array
• Regulatory Control • Process Module
• Digital Composite • Device Control
• Logic • Box Flag, Numeric, and Timer

Each of these data point types is described beginning with Section 3 of this publication. In
addition, the descriptions of the Regulatory PV (RegPV) and Regulatory Control (RegCtl)
points also contain detailed descriptions of the algorithms associated with the respective points.

1.2 COMMON FUNCTIONS

1.2.1 Point Form

Separate functional elements of the APM are used to implement various parts of typical control
loops and control strategies. Each of these functional elements can be assigned a user-defined
point name to allow for location-independent reference to the data associated with that function.
For example, points are assigned by the user for analog input and analog output slots. The I/O
Processor data (engineering-unit range for inputs, characterization option for outputs, etc.) is
configured as part of the point-build process for these points. A separate point would be
configured for each regulatory control (RegCtl) slot that would be linked to the assigned analog
I/O points through input/output connections.

The APM provides a configurable parameter called PNTFORM (Point Form) that allows the
user to define which points are to be used as the primary operator interface for point data. The
PNTFORM parameter provides the user with two choices for point form: "Full" and
"Component." Points that are configured as having "Full" point form include alarm-related
parameters and sometimes, some other miscellaneous parameters. This information is needed
when the point is to be used as the primary operator interface to the point's data.

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 1.2.1
Prior to Release 600, points that were configured as having "Component" point form did
not require descriptor data and alarm-related parameters (PTDESC, EUDESC, and
Keyword), because this type of information was suppressed for "Component" points.

Component point form should be used for points that provide inputs to the "Full" point, and
for those points that handle the outputs from the "Full" points. "Component" points should
be used as part of the "Full" point that has been designated a primary operator interface
point.

NOTE
The maximum number of points per Network Interface Module (NIM) is 8000. Both full and
component points should be counted when checking against this limit. Note that for the
DI and DO portions of a digital composite point, the inputs and outputs from/to the digital
composite point are not to be counted as part of the point total if they are implemented
using the hardware reference source and destination addresses that are entered on the
respective configuration form for the digital composite point.

CAUTION

Database security is provided to prevent an operator from starting an IOP that has an invalid
database. After initial configuration, each IOP must be set valid. Validating the database of an
IOP by selecting the VALIDATE IOP DB target on the display with the keylock in the Engineering
position causes the IOP database to be accepted as is (that is, default/null configuration or
configuration loaded from IDF). When the IOPs are marked valid, select SAVE DATA to
checkpoint the configured data. You cannot checkpoint unless the IOP database is marked
valid. Restoring the database from a valid checkpoint also sets the IOP database valid. An IOP
cannot be switched from Idle to Run unless its database is valid.

The following paragraphs provide examples of the usage of the "Full" and "Component"
point forms.

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 1.2.1

In Figure 1-2, a single-loop PID controller has the PV of a Smart Transmitter Interface
point (FT100) connected to the PV of a RegCtl point (FIC100) that has been configured for
a PID algorithm. The output (OP) of the RegCtl point is applied to an analog output (AO)
point (FY100). In this case, FIC100 is the primary operator interface and is configured as a
"Full" point. FT100 and FY100 are parts (components) of FIC100, and could be configured
as "Component" points.

PRIMARY OPERATOR INTERFACE

FOR THIS CONTROL LOOP

FIC100
PNTFORM = FT100 PV OP FY100 PNTFORM =
REGCTL
Component STI AO Component
PID ALGO

PNTFORM =
Full

SMART FIELD
TRANS- DEVICE
MITTER

Figure 1-2 — Single-Loop Example 2054

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 1.2.1

Figure 1-3 shows a single-loop PID controller that is controlling mass flow. The mass flow
is computed by the flow compensation PV algorithm in regulatory PV (RegPV) point
(FX101). FX101 receives three PVs representing the uncompensated flow, absolute
pressure, and absolute temperature from AI points FT101, PT101, and TT101. FX101
provides the PV as mass flow to a RegCtl point (FIC101) that has been configured for a
PID algorithm. FIC101 provides an output to an AO point (FY101).

In this example, FIC101 is the primary operator interface and would be configured as a
"Full" point. FX101 is part of FIC101 and would be configured as a "Component" point.
FT101, PT101, and TT101 could be configured as "Full" or "Component " points. "Full"
would be selected for any of these points that require separate alarm reporting, such as
alarming for uncompensated flow, line pressure, or fluid temperature. FY101 must be
configured as a "Component" point.

PRIMARY OPERATOR INTERFACE

FOR THIS CONTROL LOOP

FX101 FIC101
PNTFORM = REGPV PV REGCTL PNTFORM =
Component MASSFLOW ALGO PID ALGO Full

OP
PNTFORM =
Full or Component

PNTFORM =
FT101 PT101 TT101 FY101 Component
AI AI AI AO

FIELD FIELD FIELD FIELD

DEVICE DEVICE DEVICE DEVICE

Figure 1-3 — APM — Mass Flow Example 2055

APM Control Functions & Algorithms 1-7 12/03

 1.2.1

Figure 1-4 shows a single-output, single-input digital composite point (MTR100) that
interfaces a motor control circuit through digital output (DO) point MTR100OP, and digital
input (DI) point MTR100FB. In this example, MTR100 is the primary operator interface
and would be configured as a "Full" point. MTR100OP and MTR100FB are parts of
MTR100 and would be configured as "Component" points.

Note that assigning point names in this example for the standard digital input point and
digital output point is optional. These points can be alternatively referenced, using the
hardware reference addresses that would be assigned as the source and destination on the
configuration form for the digital composite point.

PRIMARY OPERATOR INTERFACE

MTR100

MTR100OP
OP
DO
(See Note)
DO

PNTFORM = TO /FROM
Full MOTOR CONTROL
CIRCUIT

MTR100FB
DI PV
DI

PNTFORM =
Component
DIGITAL COMPOSITE
POINT

NOTE: Full-point form cannot be assigned to DO (digital output) points; they

are always component points. Stand-alone digital output points
require using a digital composite point that has 0 (zero) inputs and 1 output.

Figure 1-4 — Motor Control Example 2056

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 1.2.1

Figure 1-5 shows three types of stand-alone points. FT102 and CT105 are points that could
be used for data acquisition; in this case these points would be configured as full points. For
the stand-alone digital output (DO) point SW103, a digital composite (DigComp) point
would be used and would be configured as having 0 (zero) inputs and 1
output.

FIELD FT102
DEVICE AI PV

PNTFORM = Full

FIELD CT105
DEVICE DI PV

PNTFORM = Full

FIELD OP SW103
DEVICE DO

Figure 1-5 — Stand-Alone Points 2057

1.2.2 Associated Display

With Release 510 and later software, an Associated Display can be configured for each
HPM point at build time by entering the name of a custom built schematic in the
ASSOCDSP parameter. At operating time, the operator can call up that associated custom
schematic from a point Detail Display or Group Display.

The ASSOCDSP parameter can be changed from the configuration page of the Detail
Display (for points that have a configuration page). The keylevel must = Engineer.

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 1.3

1.3 ALARMING
The following paragraphs describe the common alarming functions that can be configured
for APM points. The alarm parameters available depend on the point type. Refer to the
individual point description for details. Alarm detection and reporting for a point can be
configured only if the full point form is specified.
1.3.1 Alarm Priorities
For each point, a separate alarm priority can be specified for each alarm (for example, PV
high alarm can be low priority but PV high high alarm can be emergency). The following
alarm priorities are supported for APM points:
Emergency
High
Low
Journal
JnlPrint
Printer
NoAction
The Journal option causes alarms to be journaled only. The JnlPrint selection causes alarms
to be journaled in the HM and printed. If the Printer option is selected, alarms are printed
but not journaled. Note that if the printer is not working, alarms could be lost.
Alarm priority configuration information is maintained by the NIM.
1.3.2 Alarm Enable Status

Alarm enable status is applicable to full point forms and allows the user to enable, disable,
and inhibit alarms. This function is accomplished through the ALENBST parameter. The
alarm enable status function is resident in the NIM.

1.3.3 Contact Cutout

The main purpose of the contact cutout function is to prevent a proliferation of alarms from
being reported to the operator. This function can be used to cut out alarms on a point when they
are generated because of alarm conditions that have been detected at other points. Contact
cutout is provided for all the point types in the APM and is implemented through the
CONTCUT parameter. Another point or CL program must write to the CONTCUT parameter
in order to change the Contact Cutout state.

When the contact cutout state is applied, alarms at the point are cut out. New alarms are not
reported on the alarm summary display at the Universal Station, nor are they journaled on the
History Module or Real Time Journal. This is the same way inhibited alarms are handled except
Cutout alarms continue to be reported to the AM or CM60 for event initiated processing (EIP).
A Contact Cutout True message is journaled for points that are in alarm when cutout. For points
that are not in alarm when cut out, no message is journaled.

APM Control Functions & Algorithms 1-10 12/03

 1.3.3

On event recovery (for example, node failover), the system journals a Contact
Cutout True message for points that are currently in alarm and cut out.

When Contact Cutout is removed, points that were in alarm are checked and if the
alarm condition still exists, the system generates a new alarm with a current
timestamp. A Contact Cutout False message is journaled for points that returned to
normal while cut out. No message is journaled for points that were not in alarm
while cut out.

NOTE

When cutout is removed, it is possible to receive a Contact Cutout False message

and an alarm for the same point. This would occur if the point had changed from
an alarm state to the normal state, and back to alarm, while it was cut out.

A network configuration option provides two choices for handling unacknowledged alarms
that exist on the US Alarm Summary display when Contact Cutout is applied:
• CLEAR IMMEDIATELY clears all of the point’s unacknowledged alarms from the
display.
• CLEAR WHEN ACKED (also called the Backlight Option) leaves unacknowledged
alarms on the display and the time stamp is backlit. The alarms are cleared when they
are acknowledged.

If the second option (above) is selected, the complete backlighting action is as follows:

• When Contact Cutout is applied, unacknowledged alarms on the Alarm Summary

Display have their timestamp backlit (indicating that the alarm is inhibited).

• If an a point’s alarm state returns to normal while the point is cutout, the timestamp
remains backlit. When cutout is removed—
backlighting is removed from the timestamp
the point’s priority indicator is backlit (indicating return to normal)
a contact Cutout False message is journaled.

• If the NIM fails over while Contact Cutout is applied to any point, the point’s
tagname is backlit in addition to it’s timestamp. As soon as communication
is restored, backlighting is removed from the tagname.

When Contact Cutout is removed, backlighting is removed from cutout points.

APM Control Functions & Algorithms 1-11 12/03

 1.3.3
1.3.3.1 UCN Contact Cutout Implementation
Contact Cutout is implemented by using a logic point or a CL program to write a Boolean
variable from a primary control point into an alarmable UCN secondary point's CONTCUT
parameter. A TRUE (ON) in this parameter will cut out alarming by the secondary point.
The secondary point will not resume alarming until a logic point or CL program writes a
FALSE (OFF) into the secondary’s CONTCUT parameter.
Typical implementation of Contact Cutout uses a primary point's PTINAL parameter (point-
in-alarm indicator) to control a secondary point's CONTCUT status. This is a convenient
method for providing Contact Cutout for all primary alarms, and we recommend it as the
safest and most secure implementation. However, any other valid primary point alarm
parameter, such as PVHIFL, PVHHFL, PVLOFL, PVROCNFL, or any other valid primary
point Boolean parameter can be used. When distributing a primary point's alarm status to
the CONTCUT parameter of several points, use only one input connection to make the best
use of peer-to-peer resources.
When implementing a Contact Cutout connection using a logic point, the Logic Bad Input
handling Option parameter, LIBADOPT, must be set to OFF in case the primary point fails or is
deleted while in alarm. This implementation ensures that the secondary point's CONTCUT
parameter will be set to OFF in the event of a point failure. In addition, if the primary and
secondary points are in different UCN nodes, the logic point should be located in the same node
as the secondary point in case the node containing the primary point is idled or fails.
For the same reason, we recommend that CL programs be located in the same node as the
secondary point. CL programs should include error trapping code to handle the different
failure cases described above.
In general, Contact Cutout should be implemented using primary point alarming flags as
previously described, because these alarm parameters automatically clear (to the OFF state)
when the primary points are made INACTIVE or the node containing the primary point is
idled. Note that when connecting CONTCUT to other parameters, such as box flags or
digital composite PV flags, these parameters do not provide similar protection. Because
CONTCUT cannot be changed by the operator, it is possible to end up with a secondary
point temporarily or permanently disabled from alarming.
1.3.4 Primary Module Points
Primary Module (PRIMMOD) Points are used to collect alarms and events from points
that are related for some purpose. All UCN points with alarming capability have a
PRIMMOD parameter with which to identify a common PRIMMOD point. All points
with a matching Primmod point are considered to be in the same alarm group.
The value for the Primmod parameter can be any point in the same NIM. The
value is assigned during point build, but can later be stored by a CL program or
from schematics. If a Primmod point name is changed when alarms exist, the
alarms are reissued for the new Primmod name.
Up to 10 Primmod points can be grouped into one annunciator group in the Area data base
and Primmod points can be assigned to turn on the configurable button alarm indicators.

APM Control Functions & Algorithms 1-12 12/03

 1.3.5

1.3.5 Auxiliary Units

Alarmable NIM points in Release 520 and later software have an Auxiliary Unit
($AUXUNIT) parameter. If this parameter is set to null (- -), alarms and messages on that
point go to the primary unit. If a valid Unit ID is specified, alarms and messages from that
point go to the Auxiliary Unit.

$Auxunit can be configured at build time or, with the proper keylevel, it can be initially
assigned or changed by schematics, CL programs, the DEB alter parameters function, or
from the configuration page of the Point Detail display. The keylevel necessary to change
$AUXUNIT is configurable in the System Wide Values section of the Network
Configuration File.

Alarms from a point where $AUXUNIT has been configured are accepted only by Universal
Stations having an Area Database in which both the Primary Unit and the Auxiliary Unit are
configured.

If an $AUXUNIT assignment is changed and there are outstanding alarms on the old unit,
alarms are deleted from the old unit and added to the new unit.

1.4 RED TAGGING

A point can be "red tagged" to indicate that it requires maintenance. This is accomplished
by setting the REDTAG parameter to On. Typically, the operator sets the output of the point
to a desired safe value before putting on the red tag. Once red tagged, the mode, mode
attribute, external mode switching state, and output cannot be changed. The point cannot be
reconfigured or deleted if the red tag is On. Red tagging is supported for only the analog
output, RegCtl (only if it is outputting to an AO or a PWM DO Processor), and digital
composite point types. A point must be configured for the full point form in order to be red
tagged.

The mode and the mode attribute of the point must be changed to Man and Oper,
respectively, and the external mode switching state, if configured, must be Disabled before
the point can be red tagged. To red tag a digital composite point, the output of the point
must not be configured for the momentary state.

The Red Tag function prevents changes to the output on a point that has the REDTAG
parameter set to ON, but it may still be possible to change the output connected to the field.
For example, even if a Digital Composite point has REDTAG set to ON, a program/Logic
Block can still change the state of the Digital Output.

APM Control Functions & Algorithms 1-13 12/03

 1.5

1.5 REFERENCES

The following publications contain information related to the control functions described in
this publication:

• Control Functions in the System—System Control Functions in the

Implementation/Startup & Reconfiguration - 2 binder.

• Control Functions in the CM50S—Refer to the publications in the

Implementation/CM50S binder.

• Control Functions in the Application Module—Application Module Control

Functions in the Implementation/Application Module - 1 binder.

• Definitions of the APM Parameters—Advanced Process Manager Parameter

Reference Dictionary in the Implementation/Advanced Process Manager - 2 binder.

• Configuration, Redundancy, Failover information—Engineer’s Reference

Manual in the Implementation/Startup & Reconfiguration - 2 binder.

• Control Language—Control Language/Advanced Process Manager Reference

Manual in the Implementation/Advanced Process Manager - 2 binder.

• Command Processor Utilities—Command Processor Operation in the

Implementation/Startup & Reconfiguration - 1 binder.

• UDC 6000 Process Controller—PM/UDC 6000 Integration Manual in the

Implementation/PM/APM/HPM Optional Devices binder.

• Performance and Implementation Information — APM Implementation

Guidelines Manual in the Implementation/Advanced Process Manager - 1 binder.

• Smartline Transmitter Information — Smartline Transmitter Integration

Manual in the Implementation/PM/APM/HPM Optional Devices binder.

• Serial Interface Communications—APM/HPM Serial Interface Options in the

Implementation/PM/APM/HPM Optional Devices binder.

APM Control Functions & Algorithms 1-14 12/03

 2

I/O FUNCTIONS
Section 2

This section defines the I/O functions available in the APM analog and digital data points. The APM
control functions are described beginning with Section 3. Definitions of the parameters mentioned in
this section can be found in the Advanced Process Manager Parameter Reference Dictionary, which
is in this binder.

2.1 OVERVIEW

The analog and digital data points in the I/O Processors (IOPs) perform input and output
processing on all field I/O. These functions are performed independently of the control
functions. The partitioning of processing requirements allows more efficient use of control
processor capability and future integration of additional IOP types. The following I/O points
are available in the APM, and are described in this section:

• Analog Input—High Level

• Analog Input—Low Level

• Smart Transmitter Interface*

• Analog Output

• Digital Input

• Digital Input, Sequence Of Events

• Digital Output

• Pulse Input

• Serial Interface

To support on-line field maintenance activities, Standby Manual units are recommended for
the Process Manager AO and DO I/O Processors.

*Note that a Serial Device Interface (SDI) IOP is configured as a Smart Transmitter Interface (STI) IOP.

APM Control Functions & Algorithms 2-1 12/03

 2.2

2.2 HIGH AND LOW LEVEL ANALOG INPUT POINT

The analog input point converts an analog PV signal received from a field sensor to
engineering units for use by other data points in the APM, and by the rest of the
TotalPlant Solution (TPS) system. To accomplish this function, the analog input point
(shown in Figure 2-1) performs

• Analog-to digital conversion

• PV characterization

• Range Checking and PV filtering

• PV source selection

• Alarm detection

High level points are located in the High Level Analog Input (HLAI) IOP. One type of
low level point is located in the Low Level Analog Input (LLAI) IOP. This type is
generally used for control points. The other type is located in either the Low Level
Multiplexer (LLMUX) or the Remote Hardened Multiplexer (RHMUX) IOP. This type is
generally used for data acquisition points. The type of analog input point needed is based on
the type of field sensor that is providing the input to the point and the characterization
options selected by the user as listed in Table 2-1.

APM Control Functions & Algorithms 2-2 12/03

 2.2

PVRAW

P
V
SENSRTYP 15V DegreesC
P4 2 V DegreesF
C PVTEMP
05V H DegreesK
0-100 MV A DegreesR
PVRAW
Thermcpl R
A
Rtd Normal
C
Slidewire TCRNGOPT
T Extended
E
Therm
R
PVCHAR Rtd Direct
I
Linear INPTDIR
Z
Reverse
Sqrroot A
T
I OTD (Open Thermocouple
PVEULO
O Detection)
PVEUHI N

PVCALC
(in Eu)
PVCLAMP Noclamp
PVEXEUHI Range Clamp
PVEXEULO Checking
PVEXHIFL
& PV
TF PVEXLOFL
Filtering

PVAUTO
PNTFORM
Componnt
PVMan or PVSub Full
(from Operator or Program)
PVAUTO PV
PVSOURCE
Man/Sub Auto Auto
PVEUHI PVP (PV in %)
Man/Sub NORMALIZATION
PVEULO LASTPV

PVEXEUHI RANGE PVEXHIFL

PVEXEULO CHECKING PVEXLOFL

PV

ALENBST
Enable Inhibit
Disable
HIGHAL
Half
One A
Two L
PVALDB Three A
Four R
Five M

PVHTP PVHIFL
D
PVHPR E
• •
• T •
PV ALARM •
• E • PV ALARM
TRIP POINTS • •
• C FLAGS
AND PRIORITIES
PVROCPTP T PVROCNFL
PVROCPPR I PVROCPFL
O
N

PTINAL

Figure 2-1 — Analog Input Point, Functional Diagram 2058

APM Control Functions & Algorithms 2-3 12/03

 2.2.1

2.2.1 PV Characterization
The PV signal received from the field is characterized based on the entries that the user
makes for the SENSRTYP, PVCHAR, PVTEMP, INPTDIR, and TCRNGOPT parameters
as shown in Figure 2-1. The input PV signal is first converted to a raw PV signal (PVRAW)
whose units can be %, ratio, millivolts, microvolts, or milliohms depending on the entry
made for the SENSRTYP parameter.
The PVRAW signal is then converted to the engineering units. The engineering unit
conversions that are performed in the HLAI, LLAI and LLMUX points are listed in the
following chart, and described in the following paragraphs.
HLAI Point LLAI Point LLMUX Point (NOTE 1)
Linear Linear Linear
Square Root Square Root RTD (NOTE 2)
Thermal Thermal (with reference Thermal (with reference
Slidewire junction compensation) junction compensation)
NOTES:
1. In general, LLMUX points apply to (include) points built against the LLMUX IOP as
well as the RHMUX IOP. The RHMUX does not have a unique point type.
2. RTD is not supported by RHMUX IOP.
2.2.1.1 Linear Conversion

The PVRAW value is converted to a floating-point number. The output value of the linear
conversion is PVCALC, which is calculated based on the raw input span (for slidewire and
0-100 mV sensor types only), and the engineering unit span. The state of the input direction
parameter (INPTDIR) is taken into consideration during the calculation of PVCALC as
follows:
For slidewire and 0-100 mV sensor types, when INPTDIR is Direct:
(PVRAW - PVRAWLO)
PVCALC = (PVRAWHI - PVRAWLO) * (PVEUHI - PVEULO) + PVEULO

For 0-5V, 0.4-2V, and 1-5V, sensor types, when INPTDIR is Direct:
PVRAW
PVCALC = 100 * (PVEUHI - PVEULO) + PVEULO

For slidewire and 0-100 mV sensor types, when INPTDIR is Reverse:

(PVRAW - PVRAWLO)
PVCALC = PVEUHI - (PVRAWHI - PVRAWLO) * (PVEUHI - PVEULO)

For 0-5V, 0.4-2V, and 1-5V, sensor types, when INPTDIR is Reverse:
PVRAW
PVCALC = PVEUHI - 100 * (PVEUHI - PVEULO)

APM Control Functions & Algorithms 2-4 12/03

 2.2.1
Table 2-1 — HLAI, LLAI, and LLMUX Sensor Types and PV Characterization Options

Sensor Type AI Processor PVCHAR PV PV Bad PV

(SENSRTYP) Type Options RAW1 CALC Detection2

0 to 5 Volts HL & LL Linear % EU Range check on PVCALC

HL & LL Square Root
HL Thermocouple
HL RTD

0.4 to 2 Volts HL Linear % EU Range check on PVCALC

HL Square Root
HL Thermocouple HLAI checks for open input
HL RTD

1 to 5 Volts HL & LL Linear % EU Range check on PVCALC

HL & LL Square Root
HL Thermocouple HLAI checks for open input
HL RTD

Slidewire HL Linear Ratio EU3 Bad slidewire source, range

check on PVCALC

0 to 100 mV LL, LLMUX Linear millivolts EU3 Range check on PVCALC

RHMUX

Thermocouple LL, LLMUX, Thermocouple µvolts EU Open thermocouple, and

RHMUX range check on PVCALC

RTD LL, LLMUX RTD milliΩ EU Range check on PVCALC

LEGEND: EU = Engineering Units

HL = High Level Analog Input
LL = Low Level Analog Input
LLMUX = Low Level Analog Multiplexer
PVCALC = Calculated PV
PVCHAR = PV Characterization
PVRAW = PV received from field and converted to digital form by the A/D converter
RHMUX = Remote Hardened Analog Input Multiplexer
Notes:
1. PVRAW is the voltage signal at the APM Field Termination Assembly as a percentage of the voltage
range for the sensor type. The exceptions are as follows
a. For a thermocouple sensor type, PVRAW is in microvolts after reference junction compensation.
If an open thermocouple is detected, PVRAW is set to NaN.
b. For an RTD sensor type, PVRAW is in milliohms after lead-wire compensation. If an open RTD
is detected, PVRAW is set to NaN.
c. An external power source is used to excite the slidewire. The power source and the slidewire are
connected to separate analog input points. One power source input can be used with several
slidewire inputs.
For a Slidewire type, PVRAW is the slidewire ratio (Vin/Vsrc)
where: Vin is the FTA voltage input for this data point (slot)
Vsrc is the FTA voltage source at the slidewire source slot specified by parameter
SLWSRCID. If Vsrc is zero (fails the under-range check), PVRAW is set to "NaN."
d. For a 0-100 millivolt sensor type, PVRAW is the FTA voltage input for the slot.
2. If the diagnostics determine that the A/D converter has failed, PVRAW of the slot is set to NaN.
3. The normal operating range for PVRAW is configured by the user (for a thermocouple
0% = PVRAWLO, 100% = PVRAWHI; for a slidewire, 0 = PVRAWLO, 1 = PVRAWHI).

APM Control Functions & Algorithms 2-5 12/03

 2.2.1
2.2.1.2 Square-Root Conversion

The square-root calculation is applied to the PVRAW input such that 100% of span = 1.0.
The square-rooted value is then converted to engineering units based on the configured PV
engineering-unit range values. (For example, square root of 100% = 100%; square root of
50% = 70.71%.) The output value of the square-root conversion is PVCALC, which is
calculated based on the state of the input direction parameter (INPTDIR) as follows:

If PVRAW ≥ 0.0 and INPTDIR is Direct:

PVRAW
PVCALC = 100 * (PVEUHI - PVEULO) + PVEULO

If PVRAW < 0.0 and INPTDIR is Direct:

PVRAW
PVCALC = - 100 * (PVEUHI - PVEULO) + PVEULO

If PVRAW ≥ 0.0 and INPTDIR is Reverse:

- PVRAW
PVCALC = PVEUHI - 100 * (PVEUHI - PVEULO)

If PVRAW < 0.0 and INPTDIR is Reverse:

- PVRAW
PVCALC = PVEUHI - 100 * (PVEUHI - PVEULO)

2.2.1.3 Thermal Conversion

Thermal linearization is performed on thermocouple and RTD input types, and is selectable
by parameter PVCHAR. The following thermocouples are supported by the analog input
point:

Btherm Jtherm Rtherm Stherm

Etherm Ktherm Rptherm Ttherm

The range of the thermocouple type used with the LLAI or LLMUX points (NOTE ) can be
increased by selecting Extended as the entry for the TCRNGOPT parameter. Refer to the
APM PRD for the normal and extended ranges.

The LLAI and LLMUX points calculate the reference junction compensation from the
measured reference junction output level. This value is stored and then later converted back
to microvolts, with respect to 0 degrees C, for each thermocouple that is to be compensated.
The cold-junction reference compensation (PVREFJN) parameter is expressed in
microvolts for the specified thermocouple and is added to the microvolt value for PVRAW.

NOTE: In general, LLMUX points apply to (include) points built against the LLMUX IOP
as well as the RHMUX IOP. The RHMUX does not have a unique point type.

APM Control Functions & Algorithms 2-6 12/03

 2.2.2

The following 3-wire RTDs are supported by the analog input point:

PtDinRTD
PtJisRTD
NicklRTD
CopprRTD

For an RTD, the LLAI and LLMUX (NOTE) points calculate the lead-wire compensation
and then subtract the value from PVRAW.

NOTE: RTD is not supported by RHMUX IOP.

The maximum allowable lead-wire resistance and intrinsic safety barrier resistance for the
RTDs are listed in the following chart.

Maximum Allowable Maximum Allowable

Lead Resistance Intrinsic Safety
(Note 1) Barrier Resistance
Entire Per Entire Per
RTD Type Loop Leg Loop Leg

Pt: 100 W DIN Characterization 20 W 10 W 18 W 18 W

Pt: 100 W JIS Characterization 20 W 10 W 18 W 18 W
Ni: 120 W Edison Type 7 Characterization 20 W 10 W 18 W 18 W
Cu: 10 W SEER Standard Characterization 20 W 10 W 0.0 W 0.0 W

Note: Proper compensation for lead-wire resistance depends on the resistance being equal in
each leg of the RTD. This includes resistance due to lead-wire resistance and intrinsic safety
barriers. No provision is made to compensate for lead-wire resistance mismatch or intrinsic-
safety-barrier resistance mismatch. Both the lead resistance and the intrinsic-safety-barrier
resistance are allowed simultaneously when connected to an RTD in a Division 1 area.

2.2.2 PV Range Checking and Filtering

PV range checking ensures that the PVCALC output of PV characterization is within the
limits defined by parameters PVEXEULO and PVEXEUHI. If either of the limits is
violated, the output of the PVAUTO is set to NaN if clamping has not been specified. If
clamping has been specified, the output of the PVAUTO is clamped to PVEXEUHI or
PVEXEULO, except when PVRAW (and consequently, PVCALC) is NaN in which case
PVAUTO will be NaN.

If the range-checked and filtered value is less than the value specified by the user-
configured LOCUTOFF parameter, the final output called PVAUTO is forced to PVEULO.
First-order filtering is performed on PVCALC, as specified by the user through parameter
TF (filter lag time).

APM Control Functions & Algorithms 2-7 12/03

 2.2.3

2.2.3 PV Source Selection

The PVSOURCE parameter allows the user to select the source of the PV for this data
point. As shown in Figure 2-1, the PV can be provided by the Range Checking and Filtering
circuit (when PVSOURCE is Auto), it can be the manually entered PV (when PVSOURCE
is Man), or it can come from a sequence program (when PVSOURCE is Sub).

In addition, the PV source option parameter (PVSRCOPT) determines whether it is

permissible to change the PV source to a source other than Auto. PVSRCOPT has two
states: OnlyAuto and All. The All state allows the PV to be manually entered for this data
point.

2.2.4 Alarming

The analog input data point compares the PV to threshold values and records the alarms in
the database of the data point. The alarms are then reported by the Advanced Process
Manager Module (APMM). The parameters that are associated with alarming in the analog
input point are as follows:

$OLDEVDS PTINAL PVHIFL PVLOTP

ALENBST PVALDB PVHIPR PVROCNFL
BADPVFL PVALDBEU PVHITP PVROCNPR
BADPVPR PVEXHIFL PVLLFL PVROCNTP
CONTCUT PVEXLOFL PVLLPR PVROCPFL
EIPPCODE PVHHFL PVLLTP PVROCPPR
HIGHAL PVHHPR PVLOFL PVROCPTP
HIGHALPR PVHHTP PVLOPR

Refer to the Advanced Process Manager Parameter Reference Dictionary for the
definitions of these parameters.

2.2.4.1 Disable Input Alarming When Using Open-Line Detection

With R640, disabling annunciation of BADPV alarms for IOP-resident AI points using
open-line detection is performed using the $OLDEVDS parameter. This function is used for
disabling the BADPV alarms generated by LLAI/LLMUX IOPs for open thermocouples or
RTDs, when transmitters and positioners are physically disconnected for normal
maintenance.

APM Control Functions & Algorithms 2-8 12/03

 2.2.3

Setting $OLDEVDS from ENABLE to DISABLE removes the annunciation of BADPV

alarms for the respective point as follows:

1. There is no audible console alarm.

2. No blinking LEDs on the console or keyword.

3. Schematic behavior based on events is suppressed. Schematic behavior based on

parameters, e.g., BADPVFL, is not affected.

4. The event is removed from the alarm lists and alarm displays.

The initial value of $OLDEVDS can be ENABLE or DISABLE and can be changed
between the two values at any time from a detail display or a schematic.

However, this function is not applicable for all AI points. For other types of analog inputs,
the initial value of $OLDEVDS is NOOTDETC. When this value is set, it cannot be
changed, even by the DEB. This ensures that analog inputs other than those having open-
line detection will not have BADPV values removed from the alarm displays because the
BADPVs are a result of other factors other than $OLDEVDS being set to DISABLE.

The NIM resident parameter $OLDEVDS can be configured through the DEB and the TPS
Builder. This parameter is valid for both full and component point forms.

ATTENTION

· Only BADPV alarm events are disabled using this function.

· This function silences only the annunciation and does not

affect any operations of the system.

APM Control Functions & Algorithms 2-9 12/03

 2.3
2.3 SMART TRANSMITTER INTERFACE POINT

The Smart Transmitter Interface (STI) point provides an interface to Honeywell's advanced
series of Smartline 3000 Smart Transmitters. The STI point can support the following
Smartline Transmitter types:

• ST3000 Smart Pressure Transmitter for differential, gauge, and absolute pressure
measurements

• STT3000 Smart Temperature Transmitter for temperature, millivolts, and ohms

measurements, and

• MagneW 3000 Smart Magnetic Flow Transmitter for flow measurements

The STI points are located on the STI IOP. Each STI IOP has a maximum of 16 inputs, and
it can communicate bidirectionally with up to 16 Smartline transmitters, regardless of the
mix of transmitter types (pressure, temperature, or flow) using Honeywell’s digitally
enhanced (D.E.) protocol.

The STIMV IOP supports all of the above and multi-PV Smartline Transmitter types such
as the following:

• SCM3000 Smart Flow Transmitter (Coriolis method)

• Drexelbrook SLT Level Transmitter
• SMV 3000 Multivariable Pressure Transmitter
• SGC 3000 Gas Chromatograph

An STIMV IOP allows up to four multi-PV transmitters or a mix of multi-PV and single
PV transmitter inputs that total no more than 16. A multi-PV transmitter is configured as if
it were in n contiguous slots where n = the number of PVs expected. The STITAG
parameter value for each contiguous slot must be identical. Refer to the PM/APM Smartline
Transmitter Integration Manual for complete details.

The STI IOP and the Smartline Transmitters use bidirectional digital communication to
allow the user to configure, view, and modify the transmitter database from the Universal
Station. This digital protocol allows a more precise PV value to be transferred, thereby
permitting more accurate control of the process. In addition, the transmitter can also send a
secondary variable such as the transmitter temperature, cold junction temperature, or
totalized value, depending on the transmitter type.

The transmitter database can be configured at the Universal Station and down-line loaded to
the transmitter and the transmitter database can be up-line loaded to the STI IOP as
required, when the STI point is in the inactive state.

APM Control Functions & Algorithms 2-10 12/03

 2.3
During normal operation (when the STI point is in the active state), each time that the
transmitter broadcasts the PV value to the STI IOP, it also sends the one byte of its database
(depending on the selected DECONF mode) to the STI IOP. This allows the STI IOP to
compare the stored database to the newly received database to check for database
mismatches. If a mismatch is detected, the PV is set to NaN and the status is set to
DBCHANGE. The user can easily correct the mismatch by down-line loading the database
stored in the STI IOP.

All key transmitter parameters can be accessed from the Universal Station including

• Upper and Lower Range Values

• Damping
• PV type
• DE (Digital Enhanced communications) configuration variables
• Status of the Transmitter
• Transmitter's serial number and software revision number
• Transmitter's scratchpad

The user can access these variables through the point's Detail Display or custom-built
schematics. In addition to the tag name assigned to the process point associated with the
transmitter, the transmitter is also assigned a tag name and the access mechanism follows
the TDC3000 parameter access mechanism. This allows all the LCN capabilities applicable
to a data point to be also applicable to the Smartline Transmitters.

The STI IOP maintains a copy of the transmitter's database. When a transmitter failure
occurs, the database can be down-loaded to the transmitter. This database save/restore
feature can significantly reduce the downtime of a control loop by reducing the time in
getting a replacement transmitter in operation. The transmitter database can also be saved to
a History Module or removable media if a checkpoint request is initiated. This allows for
centralized control of the transmitter database, which significantly minimizes the effort
required to establish the transmitter database during startup or normal operation.

The STI IOP also allows the user to access the detailed status of a transmitter. The status is
displayed at a Universal Station together with the scratchpad information that has been
entered, including any maintenance notes.

Calibration of the transmitter can also be accomplished from the Universal Station. This
function allows on-line adjustment of the transmitter's working ranges so that the reference
points for a measurement are accurate.

In addition a Smart Field Communicator (SFC), which is a hand-held device, can also be
physically connected to the appropriate FTA in the APM cabinet to communicate with
Smartline Transmitters without disrupting the process, as required (refer to the appropriate
Operating Guide for Smart Field Communicators).

APM Control Functions & Algorithms 2-11 12/03

 2.3.1

2.3.1 Parameter Comparisons

To configure the STI IOP point to operate with the appropriate Smartline Transmitter, it is
necessary to know the parameter relationships between the STI IOP and the transmitter
database. Table 2-2 lists and describes these relationships.

Table 2-2 — Smartline Transmitter/STI-IOP Parameter Comparison

Smart Transmitter Corresponding Remarks

Database STI IOP
Parameter Parameter

Upper Range Value & URV Define the operating range of the transmitter.
Lower Range Value LRV These values correspond to the values for
PVEUHI and PVEULO, respectively.

Upper Range Limit & URL These parameters are the respective built-in
Lower Range Limit LRL maximum and minimum limits of the transmitter
and they cannot be changed. These parameters
are read-only parameters at the Universal
Station. URL must be configured to match the
URL value of the transmitter.

PV Damping DAMPING PV damping at the transmitter. Refer to

paragraph 2.3.2.5.

Tag Identifier STITAG Transmitter identifier. This parameter is a read-

only parameter at the Universal Station.

Software Version STISWVER Revision level of the software in the transmitter.

This parameter is a read-only parameter at the
Universal Station.

Serial Number SERIALNO Serial number (PROM ) of the transmitter.

This parameter is a read-only parameter at the
Universal Station.

Secondary Variable SECVAR For a pressure transmitter, the secondary

variable is the meter-body temperature of the
transmitter.
For a temperature transmitter, the secondary
variable is the cold-junction temperature.
For a flowmeter, the secondary variable is the
totalized value.
This parameter is a read-only parameter at the
Universal Station.

Linear / Square Root PVCHAR Refer to Table 2-3.

Characterization

Communication Mode DECONF Refer to paragraph 2.3.3.

Cold Junction CJTACT Applicable to STT 3000 only.

Compensation Active

APM Control Functions & Algorithms 2-12 12/03

 2.3.1

For more information on the STI IOP, refer to the appropriate Smartline transmitter
publication and to the PM/APM Smartline Transmitter Integration Manual. For more
information on STI IOP parameters, refer to the Advanced Process Manager Parameter
Reference Dictionary.

A detail display of a typical STI point is shown in Figure 2-2. It also shows the location of
the transmitter database parameters.

DD MMM YY 08:39:21 1

FIRST PAGE

100% - PVAUTO 13.9603 ALARM LIMITS POINT DATA

75% - PVSOURCE AUTO PVHHTP PTEXECST ACTIVE

PVCALC 13.9603 PVHITP ALENBST ENABLE
50% - LASTPV 13.9603 PVLOTP OVERVAL 100
PVLLTP PNTFORM FULL
25% - PVROCPTP PVRAW 13,9603
PVROCNTP
0% -

PRIMMOD -------
SP 0.0 CONTCUT OFF RANGE LIMITS PV COEFFICIENTS

PV 14.0 PT TYPE ANINNIM PVEXEUHI 102.9 TF 0.00000

LCN NODE 32 PVEUHI 100.0
OP% PROC NET 02 PVEULO 0.0
UCN NODE 03 PVEXEULO -2.9
DEV TYPE APM URL 1200
MOD NUM 003 URV 150.0
MOD TYPE STIM LRV 0.0
SLOT NUM 0001 LRL -200.0
STI_EU DEG_C

DD MMM YY 08:39:21 1

CONFIG PAGE
______________________CONFIGURATION DATA___________________

COMMAND
PVFORMAT D1 LOCUTOFF ------ PVLLPR NOACTION
NONE PVSRCOPT ALL PVCHAR JTHERM PVLOPR NOACTION
PVCLAMP NOCLAMP SENSRTYP STT PVROCPPR NOACTION
DNLOADDB
PVALDB ONE PIUOTDCF ON PVROCNPR NOACTION
PVALDBEU 1.00000 BADPVPR LOW
UPLOADDB ASSOCDSP PVHHPR NOACTION
INPTDIR DIRECT PVHIPR HIGH
SET_LRV
Commands ______________________SMART TRANSMITTER DATA_____________ __
SET_URV

STITAG TAPP PVRAW 13.9225 SECVAR 22.9077

COR_LRV
SENSRTYP STT URL 1200.00 DAMPING 0.70000
COR_URV PVCHAR JTHERM URV 0.00000 SERIALNO 54089305
CJTACT ON LRV 0.00000 STISWVER 1.0
COR_INPT PIUOTDCF ON LRL -199.997 STATE UPDATE
DECONF PV_SV_DB STI_EU DEG_C COMMAND NONE
**MORE**
TRANSMITTER SCRATCH PAD: TAPP 2562
TRANSMITTER STATUS : STATUS OKAY
ENTER
DATABASE DISCREPANCY: 1 OF 1

15013
Transmitter Parameters

Figure 2-2 — STI Point Detail Display

APM Control Functions & Algorithms 2-13 12/03

 2.3.1

P
V
SMARTLINE TRANSMITTER
Spt_Gp
Spt_Ap Linear C Analog
PV H PV
(from Sfm PVCHAR Linear A PV-DB DECONF
process) (output form) R
SQrroot PV-SV
SENSRTYP A
Stp-Dp Linear C PV-SV-DB
Stt T
PIUOTDCF
B Therm E
R CJACT
PVCHAR E Therm I URL
(probe type) Z
LRL
A
T URV
I LRV
NiNiMoTc
O DAMPING
N

PVRAW % Smart
PVEUHI PV Engineering Unit Direct Transmitter
PVEULO Conversion & PV Reverse INPTDIR
PVCHAR Input Direction IOP
PVCALC
(in Eu)

Range PVCLAMP Noclamp

PVEXEUHI Clamp
PVEXEULO Checking
TF & PV PVEXHIFL
Filtering PVEXLOFL

PVAUTO
PNTFORM
PVMan or PVSub Component
Full
(from Operator or Program)
PV (in Eu)
PVSOURCE

Man/Sub Auto Auto

Man/Sub NORMALIZATION PVP (PV in %)
LASTPV

PVEXEUHI RANGE PVEXHIFL

PVEXEULO CHECKING PVEXLOL

PV (in Eu)

ALARM PROCESSING Enable ALENBST

Inhibit

Half Disable
A
One
L
Two HIGHAL
PVALDB A
Three
R
Four M
Five
PVHITP PVHIFL
D
PVHIPR E •
• T •
• E •
• C •
• T •
PVROCNTP I PVROCNFL
BADPVPR O
PRIMMOD N

PTINAL

3971

Figure 2-3— Smart Transmitter Input Point, Functional Diagram 3971

APM Control Functions & Algorithms 2-14 12/03

 2.3.2

2.3.2 STI IOP Functions

A functional diagram of the STI IOP point is shown in Figure 2-3. The STI point performs
the following functions:

• PV characterization
• Range Checking and PV filtering
• PV source selection
• Alarm detection

2.3.2.1 PV Characterization

The PV signal (PVRAW) received from the transmitter has been characterized by the
transmitter in terms of linear or square-root characterization and damping. For the
STT 3000, PVRAW is further characterized based on the entries that the user makes for the
SENSRTYP, PVCHAR, and INPTDIR parameters as shown in Figure 2-3. Table 2-3 lists
the PV characterization options available for the various transmitter (sensor) types.
2.3.2.2 Linear Conversion

If the entry for PVCHAR is Linear, the PVRAW input from the FTA is calculated as a
proportion of the input span in percent, as determined from upper and lower range values
URV and LRV. This proportion is then used in generating an identical proportion of the
output span, as determined from PVEULO and PVEUHI shown in Figure 2-4. The URV
and LRV values are the 100% and 0% values that correspond to the PVEUHI and PVEULO
values, respectively.

Input to URV PVEUHI

Linear Conversion 100% Output from
Linear
Conversion

[from
(PV Value
FTA) * 100% = PVRAW ] [f(PVRAW) = PVCALC ]

0%
LRV PVEULO

Figure 2-4 — Linear Conversion, STI IOP 2726

APM Control Functions & Algorithms 2-15 12/03

 2.3.2

Table 2-3 — STI Sensor Types and PV Characterization Options

Transmitter (Sensor) Type PVCHAR PV PV PV

(SENSRTYP) Options RAW1,3 CALC Detection2

Spt_Dp (Differential Pressure) Linear % in H2O EU Range check on PVCALC

Square Root % in H2O EU Range check on PVCALC

Spt_Gp (Gauge Pressure) Linear % in H2O EU Range check on PVCALC

Spt_Ap (Absolute Pressure) Linear % in H2O EU Range check on PVCALC

Stt (Temperature)4 Linear % mV EU Range check on PVCALC

Thermocouple % oC EU Open thermocouple detect-
ion, and range check on
PVCALC.
RTD % oC EU Range check on PVCALC

RTD Ohms % Ohms EU Range check on PVCALC

Sfm (Flow) Linear % m3/Hr EU Range check on PVCALC

LEGEND: EU = Engineering Units

PVCALC = Calculated PV
PVCHAR = PV Characterization
PVRAW = PV received from transmitter and multiplied by 100 by the STI IOP
Notes:

1. PVRAW is a percentage of the configured range for the sensor type. For Multivariable transmitters,
PVRAW Engineering Units are different for each PV slot.

2. If the transmitter gross status indicates Output mode or Bad, PVRAW of the STI point is set to NaN,
and PVSTS is set to Bad

3. The normal operating range for PVRAW (0% = PVRAWLO, 100% = PVRAWHI) is configured by the
user.

4. For the supported temperature ranges, refer to the definition of the PVCHAR parameter in the
Advanced Process Manager Parameter Reference Dictionary.

2.3.2.3 Square-Root Conversion

If square root is selected, this function is performed by the smart transmitter in its
computation of PVRAW. The value for PVCALC is then determined in the same manner as
linear conversion. These conversion equations are provided below.
For INPTDIR = Direct:
PVRAW
PVCALC = 100 (PVEUHI - PVEULO) + PVEULO

If INPTDIR = Reverse:
PVRAW
PVCALC = 100 (PVEULO - PVEUHI) + PVEUHI

APM Control Functions & Algorithms 2-16 12/03

 2.3.2

2.3.2.4 Thermal Conversion

Thermal linearization is available for the thermocouple and RTD inputs of the Stt
(temperature) transmitter. Thermal linearization is selectable by parameter PVCHAR. The
following thermocouples are supported for an STI point:

Btherm
Etherm
Jtherm
Ktherm
NiNiMoTC
Ntherm
RhRad
Rtherm
Stherm
Ttherm
W5W26TC
W3W25TC

The STI point calculates the reference junction compensation from the measured reference
junction output level. This value is stored and then later converted back to millivolts, with
respect to 0 degrees C, for each thermocouple that is to be compensated. The external cold-
junction reference compensation (CJTACT) parameter is expressed in millivolts for the
specified thermocouple and is added to the millivolt value for PVRAW.

The following 3-wire RTDs are supported by the STI point:

PtDinRTD (Pt100D)
PtJisRTD (Pt100J)
NicklRTD (Ni500)
Pt200RTD
Pt500RTD
Cu10RTD
Cu25RTD

For an RTD, the STI point calculates the lead-wire compensation and then subtracts the
value from PVRAW.

APM Control Functions & Algorithms 2-17 12/03

 2.3.2
2.3.2.5 PV Range Checking and Filtering

PV range checking ensures that the PVCALC output of PV characterization is within the
limits defined by parameters PVEXEULO and PVEXEUHI. If either of the limits is
violated, the output of the range check is set to BadPV if clamping has not been specified. If
clamping has been specified, the output of the range check is clamped.
If the range-checked and filtered value is less than the value specified by the
user-configured LOCUTOFF parameter, the final output called PVAUTO is forced to
PVEULO.
PV filtering can be implemented at the STI IOP, or at the Smartline Transmitter. At the STI
IOP, first-order filtering is performed on PVCALC, as specified by the user through
parameter TF (filter lag time). At a transmitter, filtering is performed on the PV depending
on the value entered for the DAMPING parameter using the SFC. The user should decide
the type of filtering required based on the following guidelines:
• The DAMPING parameter allows for better control accuracy because more PV samples
are used in calculating the filtered PV value at the transmitter.
• TF can be changed on-process from the Universal Station. To change the DAMPING
value requires the point to be made inactive and requires the database to be down-line
loaded to the transmitter after the change has been made.
For better control accuracy, the use of the DAMPING value is preferred over the TF value.
The transmitter accepts only certain DAMPING values from the STI IOP, and the value
received must first be converted to one of the predefined DAMPING values that reside in
the transmitter. This conversion is accomplished automatically by the STI IOP by finding
the DAMPING value that is nearest to the desired DAMPING value.
DAMPING values differ between the Smartline Transmitters. The valid DAMPING values
for each transmitter type are contained in the following listing.

Valid DAMPING Values*

Pressure Temperature Flow
(Spt) (Stt) (Sfm)
0.0 0.0 0.0
0.16 0.3 0.5
0.32 0.7 1.0
0.48 1.5 2.0
1.00 3.1 3.0
2.0 6.3 4.0
4.0 12.7 5.0
8.0 25.5 10.0
16.0 51.1 50.0
32.0 102.3 100.0

* The values listed are the first-order filter time constants in seconds.

APM Control Functions & Algorithms 2-18 12/03

 2.3.2
2.3.2.6 PV Source Selection

The PVSOURCE parameter allows the user to select the source of the PV for this data
point. As shown in Figure 2-3, the PV can be provided by the Range Checking and Filtering
circuit (when PVSOURCE is Auto), or it can be the manually entered PV (when
PVSOURCE is Man or Sub).
In addition, the PV source option parameter (PVSRCOPT) determines whether it is
permissible to change the PV source to a source other than Auto. PVSRCOPT has two
states: OnlyAuto and All. The All state allows the PV to be manually entered for this data
point.
2.3.2.7 Alarming

The STI point compares the PV to threshold values and records the alarms in the database
of the data point. The alarms are then reported by the Advanced Process Manager Module
(APMM). The parameters that are associated with alarming in the STI point are as follows:
ALENBST PVHHPR PVLOPR
BADPVFL PVHHTP PVLOTP
BADPVPR PVHIFL PVROCNFL
PRIMMOD PVHIPR PVROCNPR
PTINAL PVHITP PVROCNTP
PVALDB PVLLFL PVROCPFL
PVALDBEU PVLLPR PVROCPPR
PVEXHIFL PVLLTP PVROCPTP
PVEXLOFL PVLOFL
PVHHFL

Refer to the Advanced Process Manager Parameter Reference Dictionary for the
definitions of these parameters.
2.3.3 Smart Transmitter Communication Modes
All communications between the STI IOP and the Smartline transmitters are in bit-serial
form using the Honeywell DE (digital enhanced) protocol. The communication mode for
the transmitter is selectable through the DECONF (DE configuration mode ) parameter,
whose possible entries are as follows:
DECONF Definition
Entry

Analog Not supported

Pv Transmitter communicates only the PV (4-byte format)
Pv_Sv Transmitter communicates the PV and the Secondary Variable (SV)
(4-byte format)
Pv_Db* Transmitter communicates the PV and the database (6-byte format)
Pv_Sv_Db* Transmitter communicates the PV, SV, and the database (6-byte format)

* The use of these two modes is recommended because they offer database mismatch detection and
on-process mismatch recovery.

APM Control Functions & Algorithms 2-19 12/03

 2.3.4
2.3.4 Database Considerations

During normal operation, the STI point database and the corresponding transmitter database
contain the same information. If under special conditions, the databases are not the same, a
status message appears on the STI point's Detail Display to indicate a database mismatch.
Three possible ways that a database mismatch can occur between the STI IOP database and
the transmitter database are as follows:

• Smart Field Communicator (SFC) is used to change PV-related values in the

transmitter.
• A write operation from the Universal Station to the STI IOP (during a checkpoint
restore or point building).
• The same transmitter has been reinstalled after bench calibration, or after the transmitter
electronic module has been replaced and the LRV/URV values have been modified.

The following parameters of the STI IOP database and the transmitter database are
compared when the STI IOP checks for database mismatches:

CJTACT
DAMPING
DE_CONF
FREQ60/50
PIUOTDEN
PVCHAR
SENSRTYP
STITAG
URL
URV, LRV

If a database mismatch is detected, the first four parameter mismatches are displayed in the
S1 status field of the STI point's Detail Display at the Universal Station. These mismatched
parameters are preceded by the message "DATA BASE DISCREPANCY." The user can
correct the mismatch by one of the following methods:

• Download the STI IOP database to the transmitter by issuing a DnLoadDb command
through the COMMAND parameter when the point is in an Inactive state. If the loading
is successful, the point STATE changes to OK when the point is made active.
• Upload the transmitter database to the STI IOP by issuing an UpLoadDb command
through the COMMAND parameter when the point is in an Inactive state. If the loading
is successful, the point STATE changes to OK when the point is made active.
• Correct the mismatched parameter using the SFC. If the parameter or parameters are
updated by the SFC to the same value as in the STI IOP database, the state changes
from Mismatch to OK when the next database transfer from the transmitter occurs.

APM Control Functions & Algorithms 2-20 12/03

 2.3.5

If a mismatch occurred because the Smart Field Communicator (SFC) was used to change a
parameter in the transmitter database, the data in the transmitter database may be correct. In
this case, the STI IOP does not know which value to use and issues an "SFC MODIFIED
XMTR DATABASE" message, which appears on the Detail Display. The user should wait
until the next database transfer occurs from the transmitter before taking action. At that
time, the specific change is displayed.

A database mismatch can also occur because the transmitter was miswired during
installation. This can be fixed by correcting the transmitter wiring.

For the MagneW3000, the URL value displayed on the SFC is a factor of 10 higher than the
actual value displayed at the Universal Station. The value displayed at the SFC is the scaled
limit while the value displayed at the Universal Station represents raw data. Also, the STI
IOP does not respond to changes made in the MagneW3000 database parameters for up to 3
minutes when the database changes are made using the Local Setting Card. This card is an
option that is available with the MagneW3000.

2.3.5 Point States

The STATE parameter indicates the current status of the STI IOP and the transmitter. The
various states are listed in Table 2-4.

Table 2-4 — STI IOP Point States

States Description

OK Normal state; indicates that the STI point and the transmitter are OK.
Transmitter is updating the PV value at the STI point. STATE
remains OK when the point is made inactive.

DBChange Indicates that a database mismatch between the STI point and the
transmitter has been detected. Transmitter is not updating the PV
value at the STI point. STATE remains DBChange when the point
is made inactive.

Loading Indicates that database loading between the STI point and the
transmitter is occurring.

Loadcomp Indicates that the database transfer between the STI point and the
transmitter has been successfully completed.

Loadfail Indicates that the parameter transfer between the STI point and the
transmitter has not been successfully completed.

Calib Indicates that certain parameters are being calibrated at the

transmitter by the STI point.

Calcomp Indicates that the calibration has been successfully completed.

Calfail Indicates that the calibration has not been successfully completed.

APM Control Functions & Algorithms 2-21 12/03

2.3.6 STI IOP Commands
The COMMAND parameter allows the engineer to load configuration parameters in the
smart transmitter and to calibrate the transmitter. (The point must first be placed in the
Inactive state through the PTEXECST parameter.) The enumerations of the COMMAND
parameter are as follows:

COMMAND Selection Description

DnLoadDB Load the STI IOP database into the transmitter

(down-line load).
UpLoadDb Loads the transmitter database into the STI IOP
(up-line load).
Set_LRV Set the Lower Range Value
Set_URV Set the Upper Range Value
Cor_LRV Corrects the the Lower Range Value
Cor_URV Corrects the Upper Range Value
Cor_Inpt Correct the zero point
RstCor Sets all input calibration parameters to their factory
default values.
Null A command has not been issued by the STI IOP.

The result of issuing a command to an STI IOP point is reflected in the STATE parameter
for the point.

2.4 ANALOG OUTPUT POINT

The analog output point converts the output value (OP) to a 4-20 mA output signal for
operating final control elements such as valves and actuators in the field. The OP parameter
value can be controlled from a APM regulatory point, an AM regulatory point, the operator,
or a user program, depending on the selected mode and the entries for the RCASOPT and
PNTFORM parameters.
To convert the OP value to a 4-20 mA signal, the analog output point performs
• Direct/reverse Output Function
• Nonlinear Output Characterization
An option allows redundant Analog Output points (see section 3.6). Figure 2-5 is a
functional diagram of the analog output point.

2.4.1 Direct/Reverse Output

Parameter OPTDIR allows the user to specify whether the output of the data point is direct
acting (where 4 mA = 0%, and 20 mA = 100%) or reverse acting (where 4 mA = 100%, and
20 mA = 0%). The default mode is direct acting.

APM Control Functions & Algorithms 2-22 12/03

 2.4.2
2.4.2 Output Characterization

Output characterization allows the user to specify an output transfer function, using
configurable X-Y coordinates that provide five linear segments as shown in Figure 2-6. The
length of each segment is variable according to the coordinates that can be entered as
applicable constants for OPOUT1-4 and OPIN1-4 parameters, which are real numbers.

As shown in Figure 2-6, the end points of the curve are fixed at coordinates
OPOUT0,OPIN0 (at -6.9%) and OPOUT5,OPIN5 (at 106.9%). These coordinates are fixed
at these values to ensure that neither the characterization function nor its inverse can
provide output values which are outside the -6.9% to 106.9% range.

Output (from AM Regulatory Point)

Value RCASOPT

None

Oper Cas
Output
Value (from Operator)
MODATTR MODE
None

Man
Output
Value (from Program) Prog Full

Output Componnt
(from PM Regulatory Point) PNTFORM
Value

OPTDIR OP
Direct DIRECT/
REVERSE
Reverse CALCULATION

On OPCHAR Off

OPIN0 OPOUT0
OPIN1 OPOUT1
OPIN2 OUTPUT OPOUT2
OPIN3 CHARACTERIZATION OPOUT3
OPIN4 OPOUT4
OPIN5 OPOUT5

NOTE: All parameters are shown

CALIBRATION
in the defaulted entry
COMPENSATION
positions.
OPFINAL

(To FTA) 15014

Figure 2-5 — Analog Output Point, Functional Diagram

APM Control Functions & Algorithms 2-23 12/03

 2.4.3

OPOUT5
(106.9%)

OPOUT4

OPOUT3

OPOUT2

OPOUT1

OPOUT0
(-6.9%)
OPIN0 OPIN1 OPIN2 OPIN3 OPIN4 OPIN5
(-6.9%) (106.9%)

Figure 2-6 — Output Characterization for Analog Output Point 2071

Depending on the output value, the analog output point interpolates linearly between the
two nearest values. The interpolated value becomes the output value OPFINAL.

Output characterization is an optional function that can be implemented by setting

parameter OPCHAR to On. Refer to Figure 2-5.

2.4.3 Calibration Compensation

The final stage of output processing in the analog output point is calibration compensation.
This is accomplished in the data point using internal offset and scale constants. The output
value OPFINAL is then routed to the field through the appropriate FTA.

NOTE
Slot or module level soft failures can prevent a point (or points) from outputting to the field. The
regulatory control point will initiate a "Bad Output" alarm (If configured) when any connection is
broken. If all configured point connections to the field are broken, the regulatory control point
driving that analog output slot goes into initialization.

APM Control Functions & Algorithms 2-24 12/03

 2.4.4
2.4.4 Disable Output Alarming when Using Open-Line Detection

With R640, disabling annunciation of events for an IOP-resident AO point is performed

using the $OLDEVDS parameter which disables the alarms associated with an open AO
output line. This function allows you to disable the OUTPUTFL soft failure alarms
generated by the AO IOPs when transmitters or positioners are physically disconnected for
normal maintenance.

The open-line detect parameter has two states, ENABLE and DISABLE. By default, it will
be in ENABLE state. Setting the parameter to DISABLE will disable the annunciation
events. Only the OUTPUTFL soft failure alarm events are disabled.

The NIM resident parameter $OLDEVDS can be configured through DEB and the TPS
Builder. This parameter is valid for both full and component point forms.

2.5 DIGITAL INPUT POINT

A digital input point converts a digital PVRAW signal received from the field to a PV that
can be used by other data points in the APM and the system. A functional diagram of the
digital input point is shown in Figure 2-7.

Bad PV Flag—Control strategies can test for a bad Digital Input PV. Parameter BADPVFL
is set ON when—

• The PV source has been switched to Substituted, and the point is inactive or the
module status is Idle.

• The PV source is AUTO and the PV is not being updated, because either the point is
inactive, the module is idle, there is a slot soft failure, or the FTA is missing.

The digital input point is a single-input point that can be configured as a status input, a
latched input, or for accumulation, as described in the following paragraphs.

2.5.1 Status Digital Input Point

For this digital input type, the PVAUTO value represents the state of the raw input signal
after the direct/reverse conversion is performed. The status digital-input point can be
configured for PV source selection, detection of off-normal alarms, and for reporting any
PV state changes to the system. The status digital input point is selected by entering Status
for the DITYPE parameter.

The current state of the PV input is represented on the Universal Station Group and Detail
Displays as two boxes, as shown in Figure 2-8. The boxes are lighted or extinguished
depending on the current state of PVRAW and the input direction as configured through the
INPTDIR parameter, as shown in the chart in Figure 2-8. The current PV state is also
available to be used as an input to logic slots, and other APM control functions.

APM Control Functions & Algorithms 2-25 12/03

 2.5.1

2.5.1.1 PV Source Selection

The PV source parameter (PVSOURCE) option determines the source of the PV for a status
input point. The source can be the PV input from the field (PVauto), the PV state entered by
the operator (PVman), or it can be supplied by a user program (PVsub). PVSOURCE has
no effect on the latched and accumulation options of the digital input point. If PVSOURCE
is PVauto, PV tracks PVRAW.

2.5.1.2 Off-Normal Alarming

Enabling, Disabling, and Inhibiting Off-Normal Alarms—The ALENBST parameter

allows the operator to enable (permit), disable, or inhibit the off-normal alarm. Disabling
the alarm still allows the alarm to be listed on the Group and Detail displays. Inhibiting the
alarm prevents the current PV state from being compared to the configured normal state.

Off-Normal Alarming & PV Change Reporting—Off-normal alarming can be selected

for the digital input point through the ALMOPT parameter. An off-normal alarm is
generated when the input PV state is different than the configured normal (desired) state for
the point as specified by the PVNORMAL parameter. The priority of the off-normal alarm
is determined through the OFFNRMPR parameter (ALPRIOR may also be used to maintain
compatibility with schematics and CL programs designed for pre-R500 software).

Additionally, all PV state changes can be historized as determined by HM volume

configuration.

Change Of State Reporting—Digital Input Status points (and Sequence of Events points)
can be configured for Change Of State (COS) alarm reporting through the ALMOPT
parameter. The alarm is generated when the input changes state in either direction. Alarm
priority is determined through the OFFNRMPR/ALPRIOR parameters as before.

COS alarms are removed from the Alarm Summary display following acknowledgement.
The Point does not remain in alarm so there is no Return-to-Normal. Point Detail or Group
displays will never show a point in COS alarm.

Older digital input IOPs may need to have a new firmware chip for COS reporting. Check
the IOP's detail display. For COS reporting the Digital Input IOP firmware revision must be
5.0 or later.

Note that when a point with COS reporting is changed from Inactive to Active, a COS
alarm is generated if the PV = 1. There is no COS alarm if the PV = 0. The same alarming
occurs if the point is active and the IOP is put into Run mode.

APM Control Functions & Algorithms 2-26 12/03

 2.5.1

Alarm Delay—When off-normal alarming has been configured and an off-normal alarm is
detected, the event is reported to the system. Further off-normal alarms for the same data
point are not reported until the time delay (0 to 60 seconds) specified by the DLYTIME
parameter expires. When the time delay expires, the time-delay function is disabled and the
off-normal alarm for the data point can again be reported.
For Change of State alarms, when a PV state change occurs, a COS alarm is produced and
the delay timer is started. When DLYTIME expires, two situations are possible—
• the PV is in the same state and future state changes are immediately alarmed.
• the PV is in the opposite state (it may have changed many times during the
DLYTIME period) so a second COS alarm is produced and the timer starts again.

2.5.1.3 Event Reporting

The EVTOPT parameter for the status input allows the user to optionally specify the tag
name (EIPPCODE) of a data point in the system that is to be notified when the PV changes
state, and/or specify that a time stamp be added to the reported PV state change.

For a status input point, EVTOPT has the four possible entries: None, EIP, SOE, and
EIPSOE. EIP specifies that the user supply the tag name of the data point in the system that
is to receive the PV state change, while SOE specifies that a time stamp is added to the
PV state change to establish a sequence of events.

Change of State Reporting can initiate Event Initiated Processing if the point is configured
for both COS and EIP. Note that digital input points that have COS (or Off Normal
alarming) and EVTOPT EIP configured will have EIP triggered twice. EIP processing
associated with COS reporting is not recoverable for NIM/APM failovers. Full EIP
recovery is available for DISOE points.

2.5.2 Latched Digital Input Point

To capture the occurrence of momentary digital inputs, such as from pushbuttons, requires
the user to configure the digital input point as a latched digital input point. Configuring the
point as a latched point is accomplished by entering Latched for the DITYPE parameter.

When configured as a latched input point, an input pulse that is on for a minimum of 40
milliseconds is latched true for 1.5 seconds. This ensures that any control function that
needs to monitor this event will execute at least once during the time that the signal is
latched on.

The current state of the latched PV input is represented on the Universal Station Group and
Detail displays as two boxes, as shown in Figure 2-8. The boxes are lighted or extinguished
depending on the current state of PVRAW and the input direction as configured through the
INPTDIR parameter, as shown in the chart in Figure 2-8. The current PV state is also
available to be used as an input to logic slots, and other APM control functions.

APM Control Functions & Algorithms 2-27 12/03

 2.5.2

PVRAW NOTE: All parameters are shown in

(from field) the defaulted entry positions.
Direct
INPUT
Reverse DIRECTION
INPTDIR

DITYPE
Accum

Status PV
OVERVAL
Latched
None STARTFL
1.5 Sec
Start STOPFL
Command Stop UP/ RESETFL
Reset DOWN
ACCUMULATION
PVAUTO OLDAV

PVman PV AVTVFL
(from Operator) SOURCE Countdown OVERFLOW
PVsubstituted Resetval
(from Program)
Only AVTV
All Auto
AV
PVSRCOPT
PV
DITYPE = Status DITYPE = Latched or Status
PV PV
EVTOPT
ALMOPT
None
EIPSOE
None ChngOfSt SOE EIP

Offnorml
(EIPPCODE)
DLYTIME
(TIME STAMP)
(N/A for latched inputs)
ALENBST
EIPPCODE & TIME STAMP
Enable Inhibit
(N/A for latched inputs)
Disable
PV
Printer Printer

JnlPrint JnlPrint

OFFNRMPR Emergncy Emergncy BADPVPR

ALARM
Low DETECTION Low

High High
Journal
Journal
NoAction
NoAction PVNORMFL
PVNORMAL OFFNRMFL

HIGHAL HIGHALPR 15015

Figure 2-7 — Digital Input Point, Functional Diagram

APM Control Functions & Algorithms 2-28 12/03

 2.5.2

STATE 1
BOX
(Upper)
STATETXT (1)

STATE 0
BOX
(Lower)
STATETXT (0)

PVRAW INPTDIR = INPTDIR =

State Direct Reverse

PV = ON. PV = OFF.
State 1 Box is State 0 Box is
ON lit. lit.
State 0 Box is State 1 Box is
extinguished. extinguished.

PV = OFF. PV = ON.
State 0 Box is State 1 Box is
OFF lit. lit.
State 1 Box is State 0 Box is
extinguished. extinguished.

Figure 2-8 — Input States 2065

2.5.2.1 Event Reporting

The EVTOPT parameter for the latched input allows the user to optionally specify the tag
name (EIPPCODE) of a data point in the system that is to be notified when the PV changes
state. For a latched input point, EVTOPT has two possible entries: None and EIP.

2.5.3 Accumulation Digital Input Point

The accumulation type digital input point counts the transitions of the digital input pulses
received from the field. The digital input point is configured for accumulation by entering
Accum for the DITYPE parameter.

2.5.3.1 Up/Down Accumulation

The accumulation type digital-input point can be incremented or decremented depending on

the entry made for the COUNTDWN parameter. If the entry for this parameter is Off, the
point is to be incremented by the field transitions; if the entry is On, the point is
decremented. The accumulated or decremented value is the value of parameter AV.

APM Control Functions & Algorithms 2-29 12/03

 2.5.3
2.5.3.2 Accumulator Commands

The operator has the capability of issuing start, stop, and reset commands to the
accumulator for starting, stopping, and resetting the accumulation. For resetting the
accumulator, the operator can specify the value to which the accumulator is reset by using
the RESETVAL parameter to enter the value. When the accumulator is reset, the old
accumulated value is displayed using the OLDAV parameter.
2.5.3.3 Target Value

The operator can specify the accumulator target value through the AVTV parameter. When
the accumulated value (PVAUTO) reaches the target value (PVTV), parameter AVTVFL is
set to On. AVTVFL is set to Off when the accumulator is reset.
2.5.3.4 Overflow

If the accumulated value AV overflows the accumulator (AV > 999999), the OVERFLOW
parameter is set to On. In addition, it is set to 0 when the accumulator is configured for
counting up (incrementing); it is set to 32767 if it is configured for counting down
(decrementing).

2.5.4 Sequence Of Events Digital Input Point

2.5.4.1 Description

Sequence of Events (SOE) points are used to report the order of occurrence of physical
events. The SOE digital input IOPs can use the same type FTAs as digital input cards, but
the best overall performance is obtained when using the high resolution 24 VDC Digital
Input FTAs.
SOE events are recorded in a journal with a timestamp so that you can determine, for
example, which event started an upset and the progression of events thereafter. The record
includes the point ID, point descriptor, state text unit, and time of occurrence to one ms
resolution. Refer to the Engineer’s Reference Manual for a discussion of SOE Journal size
requirements. For SOE Journal and Process Unit Journal Configuration requirements refer
to the Network Configuration Forms Instruction manual.
SOE points can also be configured for Change of State Reporting (an alarm is generated
when the input changes state in either direction). Refer to the discussion under Status
Points.
Each sequence of events IOP card provides 32 status and/or latched type inputs.
2.5.4.2 Timestamping

Timestamps are based on the "wall clock" time entered in the LCN. Time is broadcast over
the UCN every six seconds by the NIM with the lowest UCN address. To do this, the time
synch parameter (TIMESYNC) must be enabled during NIM configuration and the NIM
must contain an EPNI card. If there is a redundant NIM, its TIMESYNC parameter should
also have been enabled in case the primary NIM fails.

APM Control Functions & Algorithms 2-30 12/03

 2.5.4
The APMM receives time sync messages from the NIM and broadcasts time synch
messages on its own I/O Link every two seconds to the Sequence of Events IOPs. The IOP
time stamps an input state change with a code that is converted to, and reported as, wall
clock time by the APMMs. Each IOP can store up to 20 seconds of state changes (for all 32
points) before older events are overwritten.
If an APMM fails, or if event collection by the APMM is stopped or delayed, or if the
buffer in the IOP becomes full, the IOP rejects newer events (that is, it saves the older
events).
If the DISOE IOP hardware detects loss of one or more physical events, then an SOE Lost
event packet is passed in the System Status Journal (not the SOE Journal). This packet
contains the time at which lost events were detected, and should be used in conjunction
with the SOE journal to correlate the SOE events. SOE lost events are usually caused by a
chattering input.
2.5.4.3 Specifications and Reporting

Resolution
The operator sees one millisecond resolution as reported in the SOE Journal. Event time is
reported in hours, minutes, seconds, and milliseconds. The entries are further sorted at a
submillisecond level that affects the order of entry but does not appear in the journal.
Reporting
Typical SOE Journal entries appear as follows:
Date (MM/DD/YY)
10:50:21:848 SE150501 ON
10:50:21:849 SE150501 OFF
10:50:21:850 SE150502 ON
10:50:21:851 SE150502 OFF
Table 2-5 shows the guaranteed Minimum Physical Event Separation (MPES) values using
various Field Termination Assemblies for two digital state change events occurring be-
tween two points. In one case the events are on the same IOP. In the other case, assume that
the events are in different APMMs on two separate UCNs, logical or physical, or in case of
NIM failover. Assume that both points are using the same type of FTA. These
specifications implicitly include DISOE IOP and/or APMM failovers, are valid for stable
system operating conditions, and represents the guaranteed worst-case conditions.

Table 2-5 — Worst Case Resolution for Different System Configurations

MPES MPES
Two Turn-On Two Events (On/Off)
Digital Input FTA Type and Model # Events In Same IOP On Different UCNs
High Resolution 24 Vdc (MU/C-TDID12/52) 3.0 ms 6.5 ms
Galvanic 24 Vd c (MU/C-GDID12/13/82/83) 6.6 ms 7.4 ms
Low Cost 24 Vdc (MU/C-TDID72) 10.6 ms 10.6 ms
120 Vac (MU/C-TDIA12/52) 44.1 ms 44.1 ms
240 Vac (MU/C-TDIA22/62) 44.1 ms 44.1ms

APM Control Functions & Algorithms 2-31 12/03

 2.5.4
Figure 2-9 is a functional diagram of the SOE Digital Input point.

PVRAW NOTE: All parameters are shown in

(from field) the defaulted entry positions.
Direct
INPUT
Reverse
INPTDIR DIRECTION

DITYPE

Status
Latched

1.5 Sec

PVAUTO
PVman PV
(from Operator) SOURCE
PVsubstituted
(from Program)
Only
All Auto
PVSRCOPT
PV
DITYPE = Status DITYPE = Latched or Status PVCHGDLY
PV PV

ALMOPT

None ChngOfSt

Offnorml EVTOPT
EIPSOE None
DLYTIME SOE EIP
(EIPPCODE)

ALENBST D
(TIME STAMP) e
Enable Inhibit (N/A for latched inputs) l
a
Disable y
EIPPCODE & TIME STAMP
(N/A for latched inputs)
Printer Printer
PV
JnlPrint JnlPrint

Emergncy Emergncy BADPVPR

OFFNRMPR ALARM
Low DETECTION Low

High High
Journal Journal
NoAction NoAction
PVNORMFL
PVNORMAL OFFNRMFL

15016
HIGHAL HIGHALPR

Figure 2-9 — SOE Digital Input Point, Functional Diagram

APM Control Functions & Algorithms 2-32 12/03

 2.5.4

2.5.4.4 Configuration

Digital input SOE IOP points are configured by selecting the DIGITAL INPUT target from
the NIM Point Build Menu. The configuration considerations are similar to those described
for the conventional digital input point, with the following additions:

PNTMODTY—For Point Module Type, select DISOE.

DITYPE—Choose STATUS as the Digital Input Type. Note that the SOE IOP can be
used as a conventional digital input point if you choose Latched.

DEBOUNCE—The contact debounce time parameter specifies the time interval used to
debounce an input from mechanical contacts of a field input source. It is defined as the
length of time following an input state change during which the input must remain
unchanged in the new state to declare it a valid event. DEBOUNCE has a range of
0 - 50 milliseconds in one millisecond increments. The default value of 10 ms should
suffice for most contacts. If not, choose a value slightly longer than the
manufacturer's specified contact bounce time.

The following drawings illustrate debounce operation—

A B C

A B C D E F

11007

This waveform represents the field input. Tick marks across the waveform indicate the 200
microsecond scan intervals of the DISOE IOP hardware. Assume that the input state
changes at point A.

APM Control Functions & Algorithms 2-33 12/03

 2.6

At point B, the state change is detected. At this point, the current time and old state are
recorded. The debounce timer is started.

• if the input remains at a steady state until the debounce timer expires, then an event
is generated with a timestamp corresponding to the time of detection (point B).

• if the input changes before the debounce timer expires (point c), then the change of
state event detected at B is discarded, the timer is restarted and runs for the full
debounce time—
If a new input detected at D remains in a steady state until the debounce timer
expires (point F), then an event is generated with a timestamp corresponding to
the original time of detection (point D).

If the input has returned to the old state (dotted line at E) when the debounce
timer runs out (point F), no event is generated.

PVCHGDLY—The PV change delay parameter specifies the time of separation in seconds for
reporting two consecutive PV change events from the same input source. It is intended to prevent
repeated rapid reporting of PV change events (i.e., chattering). It can be configured over a 0–60
second range in one second increments. It applies to points configured as EIP, EIPSOE, or SOE
only. Ideally, PVCHGDLY AND DLYTIME should have the same value.

When a PV state change is detected, the change is reported and the PV change delay timer
is started.

If the PV does not change before the delay timer runs out, no further action is taken.

If the PV state changes more than once before the PV change delay timer runs out, only
the last state change is noticed and timestamped but not yet reported. When the
delay timer expires—

If the PV state changes more than once before the PV change delay timer runs out, only
the second state change is noticed and timestamped but not yet reported. When the
delay timer expires—

If the PV state is different from the state that started the timer, this event
is reported.

If the PV state is the same as the original PV state that started the timer, no event is
reported.

APM Control Functions & Algorithms 2-34 12/03

 2.6

2.6 DIGITAL OUTPUT POINT

The digital output point provides a digital output to the field based on the origin of the input
and the configured parameters. A functional diagram of the digital output point is shown in
Figure 2-10. The digital output point does not have any modes.

There are two types of digital output points: pulse-width modulated (PWM) output and
status output. Selection of the output type is accomplished through the DOTYPE parameter
shown in Figure 2-10. The PWM type is used in combination with RegCtl algorithms to
provide true proportional control. The status type output is the normal configuration for
digital outputs that are linked to digital composite points. Actual output action can be
status, latched or momentary, depending on the configuration of the digital composite point.
The default for untagged component DO points is Status.

2.6.1 Pulse Width Modulated (PWM) Output Type

The pulse width modulated output type can receive its input from a APM regulatory point
(that has been configured for a PID type algorithm) through a user-specified output
connection. The length of the pulse is derived from the OP parameter provided by the
regulatory point. Because OP is in percent, the percent value becomes the percent on-time
for the pulse whose period (1 to 120 seconds) is specified by the PERIOD parameter, as
shown in the timing diagram in Figure 2-10.

The output direction of the output signal can be configured to be direct or reverse acting by
using the OPTDIR parameter, as shown in the timing diagram in Figure 2-10.

The pulse on-time for direct and reverse acting outputs is calculated as follows:

For direct action:

OP% * PERIOD
Pulse On-Time = 100

For reverse action:

100% - OP% * PERIOD

Pulse On-Time = 100

If the value of OP is less than 0%, it is clamped to 0%; an OP with a value greater than
100% is clamped to 100%.

APM Control Functions & Algorithms 2-35 12/03

 2.6.2

2.6.2 Status Output Type

The status output type can be controlled from a digital composite-point output, a logic slot
output, or a RegCtl point (that has been configured for the PosProp algorithm) as
determined by the output connection. The output latch function is obtained by linking
digital composite-point output connections to the SO parameter. Pulsed operation (pulse-on
or pulse-off) can be obtained by linking the output connections to the ONPULSE and
OFFPULSE parameters, respectively.

The ONPULSE parameter sets SO to On for the specified duration, as shown in

Figure 2-10. At the end of the pulse time, SO is set to Off. If ONPULSE is specified as 0.0,
SO is immediately set to Off. This also applies to the OFFPULSE, except that the
OFFPULSE sets SO to Off.

If SO is received from a logic slot, the SO output of the digital output point tracks the SO
output provided by the logic slot.

2.6.3 Initialization Request Flag

When ON, this parameter indicates (for Status Output type points) that control strategies in
the APM cannot manipulate the output. Parameter INITREQ is set ON when—

• a PWM type output is configured

• a Status Output type is configured and—

the point is inactive

the module is idle

there is a soft failure such that the point is not working.

Digital Composite Points and Position Proportional Points—Note that Digital

Composite points or Position Proportional control algorithms are automatically forced to
initialize when outputting to a Digital Output point whose INITREQ is ON.

APM Control Functions & Algorithms 2-36 12/03

 2.6.3

OP (from PID Algorithm)

PWM

DOTYPE
Status
OPTDIR
Direct
Reverse

ONPULSE ON-PULSE PULSEWIDTH

GENERATOR MODULATOR PERIOD

From
Digital Composite OFFPULSE OFF-PULSE
Point or GENERATOR
Logic Block

SO
SO

(TO FTA) (TO FTA) (TO FTA)

PWM DIGITAL OUTPUT TYPE

Start of Period Start of Period

OP
(On-Time in %)

OUTPUT
OPTDIR = Direct
Period (1 to 120 Seconds)

OUTPUT
OPTDIR = Reverse

STATUS DIGITAL OUTPUT TYPE

ONPULSE
(0 TO 60 SECONDS)

SO OUTPUT

SO OUTPUT

OFFPULSE
(0 TO 60 SECONDS)

Figure 2-10 — Digital Output Point, Functional Diagram and Waveforms 2079

APM Control Functions & Algorithms 2-37 12/03

 2.7
2.7 PULSE INPUT POINT
The Pulse Input IOP accepts variable frequencies from a variety of devices such as turbine
meters, vortex type flow meters and positive displacement meters and converts input pulses
to flow rate in engineering units. Each Pulse IOP module contains eight input points. The
input frequency supported is up to 20 KHz per channel. Alarming and filtering are provided
by the IOP. Pulse Input points are configured under the Analog Input point selection on the
NIM Process Point Building Menu. Figure 2-11 is a functional drawing of the Pulse IOP.
2.7.1 Operation
For each point, the IOP is able to calculate flow rate in engineering units based on user
selected scaling factors. The Pulse IOP module always provides two related functions
simultaneously: totalizing and frequency counting.
2.7.1.1 Totalizing

Totalizing means the IOP maintains a 32-bit accumulation (AV) for each channel (updated
every 20 ms). The least significant bits are provided by the hardware accumulator. The 32-
bit entity continually rolls (i.e., there is no start, stop, or reset). The Pulse IOP only sets the
parameter AV to zero when the point is inactive, the IOP is in Idle, or an error is detected.
In the case of an error, status parameter AVSTS is set to BAD. Refer also to the Regulatory
PV Totalizer algorithm description in subsection 7.7.7.
2.7.1.2 Frequency Counting

Frequency counting is expressed by parameter PVRAW.

PVRAW = Delta_AV = Pulses Per Second

Elapsed Time in Seconds
The frequency of the input pulse train must be greater than 0.4 Hz for the calculated PV for
that point to be correct. The AV is correct under all circumstances.
2.7.1.3 PVCALC

PVCALC is PVRAW after scaling (e.g., barrels per minute)—

PVCALC = C1 * TIMEBASE * PVRAW

C2
C1 is an engineering units scale factor and is dimensionless, e.g., barrels per gallon.

TIMEBASE is a time scale factor. The choices are seconds, minutes, or hours.
C2 is a meter factor in pulses per engineering unit (e.g., pulses per gallon). If the instrument
vendor instead supplies the factor K in engineering units per pulse (e.g., gallons per pulse),
then C2 must represent the reciprocal of the factor K, i.e., C2 = 1/K.

APM Control Functions & Algorithms 2-38 12/03

 2.7.1

P AV
V $ACCSRC

PVRAW 32-BIT
C PV
ACCUMULATION
H
A
R
A
Seconds C C1
T
TIMEBASE Minutes C2
E
Hours R
I
Z
A
T
I
PVEULO
O
PVEUHI N

PVCALC
(in Eu)
PVCLAMP Noclamp
PVEXEUHI Range Clamp
PVEXEULO Checking
& PV PVEXHIFL
TF PVEXLOFL
Filtering

PVAUTO
PNTFORM
Componnt
PVMan or PVSub Full
(from Operator or Program)
PVAUTO
PV
PVSOURCE

Man/Sub Auto Auto

Man/Sub PVEUHI NORMALIZATION PVP (PV in %)
PVEULO LASTPV

PVEXEUHI RANGE PVEXHIFL

PVEXEULO CHECKING PVEXLOFL

PV

Enable ALENBST
Inhibit
Disable
Half
One A
Two L
PVALDB Three A HIGHAL
Four R
Five M

PVHITP PVHIFL
D
PVHIPR E
• •
T •
PV ALARM • •
• E • PV ALARM
TRIP POINTS • •
• C FLAGS
AND PRIORITIES
PVROCPTP T PVROCNFL
PVROCPPR I PVROCPFL
O
N

PTINAL

Figure 2-11 — Functional Diagram, Pulse Input IOP 3364

APM Control Functions & Algorithms 2-39 12/03

 2.7.1

2.7.1.4 Rate Value

The rate value is treated similar to an analog input PV and is supported by high/low alarms,
Rate of Change (ROC) alarming, filtering, etc., on a half second processing interval (every
four seconds for ROC only).

The Pulse IOP calculates the unsigned integer AVDELTHS every half second.
AVDELTHS is the change in AV from the last half second and is intended for display
purposes. The parameter’s value is normally constant, but the operator will observe a
change if the pulse input rate varies.

2.7.1.5 Pulse Period

The pulse period (1/PV) can be determined with CL.

APM Control Functions & Algorithms 2-40 12/03

 2.8
2.8 SERIAL INTERFACE
The Serial Interface IOP provides bidirectional interfaces to various programmable logic
controllers (PLC) and other Honeywell-approved serial devices that are compatible with
one of several interfaces.
Figure 2-12 is a block drawing of the Serial Interface IOP and associated hardware.

APM

FTA To Field
1 Device

SI Power
IOP Panel

FTA To Field
2 Device

11008
Figure 2-12 — Serial Interface Point Hardware, Block Diagram

Communications to the field device is by EIA RS-232D or EIA RS-485 standards*.

RS-232D communication has a limit of 15 meters (50 feet) and RS-422/485 protocol is
supported to 1.2 km (4000 feet). You can extend EIA RS-232D Communications between
an FTA and a field device with appropriate MODEMs.
2.8.1 Operation
Each Serial Interface IOP connects to one or two FTA assemblies. There are 32 slots per
Serial I/O card. 16 slots can be configured to FTA-1 and 16 slots can be configured to FTA-
2. Plug-in modules adapt the FTAs for different communications protocols and
applications. Qualified applications include—
Modbus Interface (Modicon Modbus-RTU protocol with extensions for real numbers
and string support):
Modicon 984 programmable logic controller
Rosemount Micro-Motion Transmitter
Other Honeywell-approved Modbus compatible devices
Allen-Bradley Interface:
Allen-Bradley PLC-2, 3, and 5 programmable logic controllers
Other applications are being developed.
Each of the 32 Serial Interface slots can support up to 512 Flags, 16 Reals, 32 Integers, or
64 ASCII characters of contiguous data to/from a field device.

*Not all signals are supported

APM Control Functions & Algorithms 2-41 12/03

 2.8.2

Each active SI slot must have a corresponding Array point. Data collected through the
SI slot is available as local data for use by Digital Composite points, Device Control points,
CL programs, etc. Array points are described in Section 10.

Flags and Numerics are fully supported as I/O connections; however, the Serial Interface is
primarily intended as an input vehicle and it can efficiently import large quantities of data.

Additionally, the Serial Interface IOP firmware runs diagnostic routines. It monitors and
reports any detected communications timeouts or errors between the IOP and FTAs.

2.8.2 Configuration

On the APMM Node Specific Configuration display, you must choose an APMM scan
period (SCANPER). The APMM scan period specifies the scan period in seconds at which
the APMM images the Serial Interface IOP database to the Array points. During Node
Specific Configuration, you must also specify the IO Module Numbers that contain SI
cards. Otherwise, no specific configuration is required for an SI slot, except what is entered
for the associated Array point. Array points are described in Section 10 of this manual.

The maximum number of SI and associated Array points at the three configurable scan
periods are—

Scan Period Maximum No.

in Seconds of Slots Scanned
1 80
.5 40
.25 20

Communication protocol in the FTA firmware is customized by Honeywell for specific

uses. The SI IOP’s Detail Status display shows the protocol, baud rate, and parity type
configured for each FTA. If a fault exists, the configuration information is replaced with a
failure message.

2.8.3 Checkpointing and Startup

Checkpointing—SI slot data is not checkpointed, but SI configuration is contained in the

APMM Array point checkpoint. Configuration of related Array points is saved.

Startup—SI slot configuration data is automatically reloaded on every startup. When

reloaded, the SI IOP Database Valid parameter is automatically set to Valid.

APM Control Functions & Algorithms 2-42 12/03

 2.9
2.9 SERIAL DEVICE INTERFACE

The Serial Device Interface (different from the Serial Interface) uses a Serial Device
Interface (SDI) module and a Companion Field Termination Assembly (FTA) designed to
transfer serial data from and to specific external devices.

Communications with the device mimics a Smart Transmitter analog input point. The SDI
module is configured as you would for a Smart Transmitter Interface Module (STIM).

Currently interfaces for the following devices have been developed:

• Manual/Auto Station
• Toledo Weigh Scale, Model 8142-2089
• Toledo Weigh Scale, Model 8142-2189
• UDC 6000 Process Controller

2.9.1 Serial Device Interface Description

Each SDI board can support two serial channels and each FTA can communicate in
ANSI/EIA-232 (RS-232) or EIA-422/485. The EIA-232 interface connects to one serial
device and the EIA-485 interface can connect to a multidrop network of up to eight devices.

Figure 2-13 illustrates the Serial Device Interface.

APM
FTA To Field
1 Device

SDI (e.g., EIA-232 device)

Power
IOP Panel

FTA To Field
2 Device
(e.g., EIA-485 device)

11393
Figure 2-13 — The SDI Interface

2.9.1.1 Implementation and Control

Implementation —You can communicate directly with the SDI using CL or control
algorithms. Other implementation methods are described in the Process Manager
Implementation Guidelines or the PM/UDC 6000 Integration manual (see References).

Control—Operators typically control an SDI device from a custom schematic. You can
build your own schematic or contract with Honeywell Engineering Services to build it.

APM Control Functions & Algorithms 2-43 12/03

 2.9.2

2.9.2 Manual/Auto Station Interface

The Manual/Auto Station interfaces with the Process Manager through the Serial Device
Interface FTA using EIA-485 protocol at 19.2 k baud. Up to four M/A Stations can be
connected in multidrop to each of the two SDI FTAs. Each of eight slots in the SDI IOP can
be configured for use with one Manual/Auto station. Slots 1–4 correspond to logical
address for FTA one and slots 9–12 correspond to logical address 1–4 on FTA two (slot one
= M/A Station 1 on FTA1, etc. and slot–9 = M/A Station 1 on FTA2 etc.).

Refer to the Advanced Process Manager Implementation Guidelines manual for additional
information.

2.9.2.1 Communications

Invalid data—Both data received from the SDI IOP and data received from the Manual
Auto Station are checked for reasonableness. Very small values may be rounded to .001.
Very large (absolute) values are either rejected or stored as NaN.

Time out—A time out signal is sent from the SDI IOP to the FTAs every half second. Loss
of this signal for 10 seconds or more halts all communications with the Manual/Auto
Stations connected to that FTA.

Communication failure—When communications between the FTA and an M/A Station

fails, the FTA makes two attempts to send the last message after the time out, then the point
is put in bad input soft failure. As long as the slot remains active, there is an attempt to
restore communications, but the M/A station is marked as not communicating.

Refer to the Manual/Auto Station manual for additional information on the Manual/Auto
Station itself.

APM Control Functions & Algorithms 2-44 12/03

 2.9.2

2.9.2.2 Implementation

The PV and OP process signals are directly connected to appropriate modules in the PM.
Process and status signals are sent from the PM to the M/A station and operator changes to
the Set Point at the M/A station are read into the PM as if those changes were at a Universal
Station. Figure 2-14 illustrates a typical Manual Auto Station implementation.

Unless the PM Override flag is set, the PM responds to SP, OP, or mode change operations
from the M/A Station's front panel. The PM Override function can inhibit operator
functions attempted from the M/A station front panel that would affect SP, OP, or Mode.

APM

FTA

PV
HLAI

Regulatory Field
Control Signals
Point
OP
AO

FTA

FTA
M/A M/A
Station Station
Logic SDI Power
Blocks IOP Panel
M/A
Station

FTA

11394
Figure 2-14 — M/A Station Implementation

APM Control Functions & Algorithms 2-45 12/03

 2.9.2

Tables 2-6 through 2-8 show how to relate parameters seen at the Universal Station through
the STI point and their meaning as Manual/Auto station parameters.

Table 2-6 — PV Related Parameters Sent to the Manual Auto Station

Parameter Meaning as an STI Point As an M/A Station Comments

Parameter Parameter

LRV Low end of operating range Low end of operating PV (in engineering
for PVRAW range for PVRAW units)

PVEUHI PV high range in eng. units PV high range in Must be set to 100.0
engineering units

PVEULO PV low range in eng. units PV low range in Must be set to 0.0
engineering units

PVEXEUHI PV extended range high PV extended range high Must be set to 100.0
limit in engineering units limit in eng. units

PVEXEULO PV extended range low limit PV extended range low Must be set to 0.0
in engineering units limit in engineering units

Table 2-7 — Control, Status and Other Parameters Sent to the Manual Auto Station
Parameter Meaning as an STI Point Parameter As an M/A Station
Parameter
CJTACT Internal cold junction reference active OFF = Manual Mode
ON = Auto Mode
DAMPING Damping M/A Station Alarms:
1 = Alarm 1 true
2 = Alarm 2 true
3 = Both Alarms true
PIUOTDCF Open thermocouple detect enable ON = In Override
OFF = Not in Override
PTEXECST Point execution state Active = Point is active
Inactive = Point is inactive
PVTV PV target value Setpoint in eng. units

STITAG Transmitter tag name M/A Station Tag Name

URL Upper range limit of PV OP in per cent

URV Upper range value of PVRAW Valve position in per cent

APM Control Functions & Algorithms 2-46 12/03

 2.9.2
Table 2-8 — Parameters Sent from the Auto Manual Station
Parameter Meaning as an STI Point Parameter As an M/A Station Parameter
PVRAW Raw PV input value Setpoint (in eng. units) from
M/A Station
SECVAR Value of Secondary Variable OP (in per cent) from the
M/Auto Station)
SLOTSF Slot soft failures Soft failure due to bad input

STATE Current point state FTA Information

STI_EU Smart Transmitter, engineering units Change Requests:

INH2O 0 = No change request
MM_HG 1 = SP change request
PSI 2 = OP change request
KPA 3 = Manual Mode request
MPA 4 = Auto Mode request
STISWVER Smart Transmitter software revision level FTA information:
(sent from FTA)
Slot 1 = M/A application
Slot 2 = Software gen date
Slot 3 = Software rev date

In addition to configuring the SDI IOP as an STI point, at least one, and preferably two
logic points must be built to read data from each M/A station, perform necessary processing
and then write the processed data, control, and status signals back to the M/A station.

The primary logic point handles the control functions and the following rules apply:

Parameter Change Requests (STI_EU)—an SP or OP change request takes on the

enumeration value shown for approximately five seconds, after which it is reset to 0
(H2O) indicating no change request. Manual Mode change request and Auto Mode
change requests are similar except their enumeration value is reset to 0 (H2O) as soon as
the new mode is written to the M/A station (by means of CJTACT).

OP (SECVAR)—An OP request is read from the Manual/Auto Station, processed and

written back to the M/A Station through the URL parameter.

SP (PVRAW)—An SP request from the Manual/Auto Station is processed and written

back to the Manual/Auto Station using the PVTV parameter.

APM Control Functions & Algorithms 2-47 12/03

 2.9.2

The second logic point is optional and is used to write back information such as Valve
Position, Alarm state, and the Override flag using the parameters shown in the tables.

Refer to the Advanced Process Manager Implementations Guidelines (see References) for
detailed information about implementing the above rules.

2.9.2.3 Operating Considerations

To modify any Regulatory Control Point parameter from the M/A station, the external
Mode Switching Enable parameter ESWENBST must be set to ENABLE.

The Regulatory Control Point’s Mode attribute parameter (MODATTR) must be set to
PROG so that OP can be modified by a Logic point.

Only a one second scan period is supported for the M/Auto Station Logic points.

The PV High, PV Low, and PV Extended Range parameters must be configured with the
values shown in Table 2-6 in order to transfer an SP change request to the Regulatory
Control point’s set point parameter SPP.

APM Control Functions & Algorithms 2-48 12/03

 2.9.3
2.9.3 Toledo Weigh Scale Interface
Toledo Weigh Station models T8142-2089 and T8142-2189 interface with the Advanced
Process Manager through the Serial Device Interface IOP using RS-232-D protocol at 9600
Baud. One Toledo Weigh Station can be connected to each of the two SDI FTAs. Slots one
and nine in the SDI IOP can be configured as to communicate with the Toledo Weigh
Station. The SDI IOP is implemented as a Smart Transmitter Interface Module (STIM).
2.9.3.1 Communications

Invalid data—The following parameters are checked for reasonableness: DAMPING,

PVTV, URL, LRV, and DECONF.
Communication failure—When communications between an FTA and a Toledo Weigh
Station fails, the FTA makes two additional attempts to send the last message, then the
Toledo Weigh Station is marked as not communicating and PVRAW (the weight) is set to
NaN.
To recover from most communication failures, switch the point execution status
PTEXECST to inactive and back to active.
Scan Rate—Weight (PVRAW) and Flow Rate (SECVAR) are updated every 250 ms or
faster.
Refer to the Toledo Weigh Scale manual for more information.
The following tables explain the parameters used to communicate with the Toledo Weigh
Scale using an SDI interface configured as an STI module.

Table 2-9 — Parameters Sent from the Toledo Weigh Station

Parameter Meaning as an STI Point Parameter Meaning as a Weigh Scale
Parameter
PVRAW Raw PV input value Weight (W)

SECVAR Value of Secondary Variable Flow Rate (R)

STI_EU Smart Transmitter, type of eng. units used Feed Status:

0 = In_H2O Feed is Off (x)
1 = MMHg Feed is On (F)
2 = PSI Feed is in alarm (A)
STISWVER Smart Transmitter software revision level FTA information:
(sent from FTA)
Slot 1 = Application
Slot 2 = Software gen. date
Slot 3 = Software rev. date

APM Control Functions & Algorithms 2-49 12/03

 2.9.3
Table 2-10 — Parameters Sent to the Toledo Weigh Station
Parameter Meaning as an STI Point Parameter Meaning as a Weigh Scale
Parameter
CJTACT Internal cold junction reference active Feed Control:
On = Start Feeding/Feeding
Off = Not Feeding
DAMPING Damping Weight Filter (F)*

PIUOTDCF Open thermocouple detect enable Mode:

On = Ascending Mode (A)
Off = Descending Mode (D)
PVTV PV target value Weight Setpoint* (S)

URL Upper range limit of PV Alarm Setpoint* (A)

LRV Low end of operating range for PVRAW Decimal Point Position (D)
1 = 1.0
2 = 0.1
3 = .01
4 = 0.001
5 = 0.0001
DECONF Digitally Enhanced Configuration Mode Parity Selection:**
0 = No Parity
1 = Odd Parity
2 = Even Parity
3 = No Parity
4 = No change
LRL Lower Range Limit Weight recorded when feed
status switched from On to Off.

* Values are modified to 6 digits or less by moving the decimal point per LRV.
** Odd parity should not be used. Even parity is preferred.

APM Control Functions & Algorithms 2-50 12/03

 3

CONTROL FUNCTIONS OVERVIEW

Section 3

This section provides an overview of the control functions available in the APM. Definitions of the
parameters mentioned in this section can be found in the Advanced Process Manager Parameter
Reference Dictionary.

3.1 CONTROL PERFORMANCE

The Advanced Process Manager is a high-performance device capable of an assured rate of

160 regulatory control loops per second. Users can customize their control configuration to
meet the application requirements.

The parallel processing architecture of the Advanced Process Manager allows the control
processing capability of the APM to be totally independent of other APM functions such as
the number of I/O points built, data requests for APM data from the Network Interface
Module and other UCN devices, and alarming functions; therefore, only two factors must
be considered when configuring the control processing: control slot type, and the
scheduled frequency of execution otherwise referred to as scan rate. These factors are
described in the following paragraphs.

3.1.1 Control Slot Types

The following control slot types are resident in the Advanced Process Manager Module:

Slot Type Max No. of Applicable Remarks

Points (Slots)* Parameter

Digital Composite 512 NDCSLOT Refer to Section 4

Device Control 160 NDEVSLOT Refer to Section 11
Logic Slot 80 NLOGSLOT Refer to Section 5
Process Module 160 NPMSLOT Refer to Section 6
Regulatory PV 80 NPVSLOT Refer to Section 7
Regulatory Control 160 NCTLSLOT Refer to Section 8
Array 256 NARRSLOT Refer to Section 10

*Subject to limitation of execution time.

The point mix is defined by specifying the number of slots of each type using the
NDCSLOT, NLOGSLOT, NPMSLOT, NPVSLOT, NCTLSLOT, NDEVSLOT, and
NARRSLOT parameters that are found on the UCN/PM Configuration Form. This
configuration form allows the user to specify the particulars of the APM Box Data Point.

APM Control Functions & Algorithms 3-1 12/03

 3.1.2

The slot numbers for each point type range from 1 to the user-specified maximum number
listed in the above chart. For example, if NPVSLOT is set to 35, the RegPV points can be
configured in any RegPV slot from slot 1 to slot 35. Similarly, if NLOGSLOT is set to 40,
the logic points can be configured to run in any logic slot from slot 1 to slot 40. The point
types and slot numbers are used for the initial configuration of a data point and for
specifying the processing order.

3.1.2 Scan Frequency

Regulatory type (RegPV, RegCt1) and digital type (DigComp, DEVCTL, and Logic) slots
can be configured for scanning at different rates as specified by the SCANRATE parameter
and by the Fast Slots parameters. SCANRATE deals with the base scan rate for all points
of a certain type. The Fast Slots parameters allow a specified number of regulatory or
digital type slots to be processed at a quarter second rate without regard to the base scan rate
for the rest of the group. These are APM Box Data Point parameters. Array points are not
processed (require zero PUs) so they are not affected by the SCANRATE parameter.

3.1.2.1 Scan Rate

The scan rates indicate the number of times that all slots of that particular type (except Fast
Slots) are scanned and processed each second. For example, a scheduled frequency of 1/4
sec for the regulatory slots indicates that all the regulatory slots in this APM will be scanned
and processed four times each second. The scan rate has an impact on the number of slots
that can be processed as described in paragraph 3.1.3.

The following chart contains the scheduled frequency of the respective entries for the
SCANRATE parameter:

Entry for RegCtl & RegPV Slots Logic, DigComp, DevCTL ProcMod Slots
SCANRATE Parameter Scheduled Freq. Scheduled Freq. Scheduled Freq.

Reg1Log1 1 sec 1 sec 1 sec

Reg1Log2 1 sec 1/2 sec 1 sec
Reg1Log4 1 sec 1/4 sec 1 sec
Reg2Log2 1/2 sec 1/2 sec 1 sec
Reg2Log4 1/2 sec 1/4 sec 1 sec
Reg4Log4 1/4 sec 1/4 sec 1 sec

3.1.2.2 Fast Slots Parameters

Fast Slots parameters allow a specified number of the regulatory control, regulatory PV,
digital composite, or logic slots to be processed at a quarter second rate without regard
to the scan rate for the rest of the group. When fast slots are specified, they are the lower
numbered slots for that type. For example, if there are 50 regulatory control slots and 15 are
specified as Fast (NFASTCTL = 15), then slots 1-15 are scanned every quarter second, and
slots 16-50 are scanned at the rate specified by the parameter SCANRATE.

APM Control Functions & Algorithms 3-2 12/03

 3.1.2

The Fast Slots parameters are—

• NFASTCTL Number of Fast Regulatory Control slots
• NFASTDC Number of Fast Digital Composite slots
• NFASTPV Number of Fast Regulatory PV slots
• NFASTLOG Number of Fast Logic slots
• NFASTDEV Number of Fast Device Control slots
If the SCANRATE parameter is configured for four times per second, then all of the points
for those types are scanned at the quarter second rate and the number of fast slots is forced
to the same as the total number of slots for that type. For example, if SCANRATE =
REG1LOG4, then the number of Fast Logic slots parameter (NFASTLOG) are set equal to
the number of Logic slots (NLGSLOT).
PERIOD—this parameter shows the processing period in seconds. Refer to the Advanced
Process Manager Parameter Reference Dictionary for additional information.
3.1.2.3 Point Processing Executive

The point processing executive in the APMM runs at quarter-second (or 250 milliseconds)
intervals or "cycles." (Each quarter second cycle is further divided into two sub cycles to
provide a breakpoint for database synchronization.) Slot scheduling determines the
assignment of slots to cycles and the ordering within a cycle. This operation is
automatically performed at the time of transition from IDLE to RUN state, based on the
following rules.
• There are four cycles per second. The slots executing at four times per second are
processed on every cycle. The slots executing at two times per second are processed on
every other cycle, and the slots executing once per second are processed on every fourth
cycle.
• Each slot type has a different processing weight assigned to it. The slots processing
slower than four times per second are distributed between the four cycles to equalize the
processor loading (to whatever extent possible) of each cycle.
The processing order of the slots within a cycle is determined based on the point type as
follows (from left to right):
RegPV Fast RegPV ProcMod Logic Fast Logic
DevCtl Fast DevCtl DigComp Fast DigComp
RegCtl Fast RegCtl
Within each point type, the slots are processed in the descending order of the slot
number (that is, from highest slot number, down to one).

APM Control Functions & Algorithms 3-3 12/03

 3.1.3

3.1.3 Determining Processing and Memory Capacity

The processing power of the APM control processor is measured in terms of "Processing
Units (PUs)." Each control processor has an assured rate of 160 PUs per second. Each slot
type consumes a certain amount of PUs subject to the scheduled frequency.

The relationship between the scheduled frequencies and the Processing Units for the slot
types are contained in the following chart. Please note that slots use more Processing Units
at faster frequencies.

PUs Per Second at Scheduled Frequencies

Slot Type 1/4 sec 1/2 sec 1 sec

Digital Composite 0.4 PU 0.2 PU 0.1 PU

Device Control 4 PU 2 PU 1 PU
Logic 4 PU 2 PU 1 PU
Process Module N/A N/A 1 or 2 PUs
Regulatory PV 4 PU 2 PU 1 PU
Regulatory Control 4 PU 2PU 1 PU
Array 0 PU 0 PU 0 PU
String 0 PU 0 PU 0 PU
Timer 0 PU 0 PU 0 PU
Flag 0 PU 0 PU 0 PU
Numeric 0 PU 0 PU 0 PU

Process Module Points—When configuring each APM, you can choose how many
processing units are allocated for its Process Module points.

• If parameter SEQPROC = 1_PU, one PU is allocated per Process Module point per
scan and up to 40 Process Module points can be processed each quarter-second cycle.

• If parameter SEQPROC = 2_PU, two PUs are allocated per Process Module point
per scan and up to 20 Process Module points can be processed each quarter-second
cycle.

In batch applications where many small sequences are needed and you want all of them
loaded at the same time, 1_PU is the appropriate choice for parameter SEQPROC.

Process module points in software releases R230 (and earlier) always used two processing
units, therefore, parameter SEQPROC should be set to 2_PU if updating from R230 and
earlier versions.

APM Control Functions & Algorithms 3-4 12/03

 3.1.3

Memory Units—APMM capacity is measured in terms of Memory Units. For the point
database and sequence programs, the maximum capacity is 15,000 Memory Units (MU)
allocated as follows:

Memory Units Memory Units

Slot Type Per Point Slot Type Per Point

Digital Composite 5 Sequence Programs 1

Logic 15 Numerics 1/16*
Process Module 15 Flags 0
Regulatory PV 12 Device Control 30
Regulatory Control 13 Array 8
String 1/8* Times 3/32*
Timer 0

* 8 strings = 1 MU, 16 Numerics = 1 MU, 32 Times = 3 MU.

Any mix of the preceding slot types can be used, but the mix is subject to the following
constraints:

1. Point mix used must not exceed 160 Processing Units or 15,000 Memory Units per
APM.
2. Absolute number of each slot type per APM cannot exceed the maximum shown in
the following chart (regardless of the available PUs):

Slot Type Max. No.

Digital Composite 512

Device Control 160
Process Module 160
Regulatory PV 80
Regulatory Control 160
Logic 80
Array 256 (80 external max.)
Numeric 16,384
String 16,384
Time 4096

APM Control Functions & Algorithms 3-5 12/03

 3.1.3
The following are two examples of possible configurations that show the PU calculations.
Example 1:
Slot Type Slots Freq PUs/Slot Total PUs/Slot Type
Regulatory Control 160 1 sec 1 PU 160 X1 = 160 PU
Digital Composite ---- ---- ---- ----------
Logic ---- ---- ---- ----------
Process Module ---- ---- ---- ----------
Regulatory PV ---- ---- ---- ----------
Total PUs for this APM = 160 PUs
Example 2:
Slot Type Slots Freq PUs/Slot Total PUs/Slot Type
Digital Composite 50 1/4 sec 0.4 PU 50 X 0.4 = 20 PUs
Logic 10 1/4 sec 4 PU 10 X 4 = 40 PUs
Process Module 10 1 sec 2 PU 10 X 2 = 20 PUs
Regulatory PV 10 1/2 sec 2 PU 10 X 2 = 20 PUs
Regulatory Control 30 1/2 sec 2 PU 30 X 2 = 60 PUs
Total PUs for this APM = 160 PUs
Invalid configurations are displayed as errors when the information is being loaded into the
APM through the Universal Station.
3.1.3.1 Overrun Handling

The APM has the capability to handle most configurations of up to 160 PU without
encountering an overrun. Overruns occur when a specific task cannot be completed in the
allowed time. The following three kinds of overruns are possible in the APMM.
• Point Processing
• I/O Link Access
• UCN Access (Peer-to-Peer Communication)
Point Processing Overrun—A point processing overrun occurs when the slots that are
scheduled to be processed during any subcycle cannot be finished within the allocated time
of 125 msec. When this occurs, all the points are processed to completion (nothing is
aborted), but the following subcycle is delayed until the next 125 msec subcycle. Also, the
current hour point processing-overrun counter is incremented by 1.
The primary cause of point processing overruns are several long sequence programs that are
processing on the same subcycle. If a point processing overrun occurs for four seconds in a
row (on any subcycle within each second), a point processing-overload soft failure is
generated. The soft failure is reset when an overrun does not occur for eight seconds.

APM Control Functions & Algorithms 3-6 12/03

 3.1.3

For each subcycle, the current hour and previous hour point processing-overrun counters are
maintained in the APMM and displayed on the UCN Detailed Status Displays to help track
down the cause of the overrun.

I/O Link Access Overrun—This type of overrun occurs when parameter read or write
access requests, from slots residing in the APMM to I/O Processors in the same APM, are not
completed within a cycle time. This indicates that too many parameter access requests were
attempted through the I/O link within the last cycle (250 msec). When this occurs, point
processing is delayed by 125 msec and the I/O link overrun counter is incremented by 1. This
continues until the requested data becomes available. I/O link accesses to some parameters
are not counted as I/O link accesses, and accesses to them are considered as being
"unlimited." These are the digital input point’s PV (parameter PVFL) and BADPVFL, and
the Digital Output point’s SO, and INITREQ parameters.

The anticipated average number of I/O link accesses (from APMM points within the same
APM) is 120 parameters for each 250 msec cycle. Access overruns can be expected when
the number of I/O link accesses exceeds 200 parameters for each 250 msec cycle.
If an I/O link overrun occurs for four seconds in a row (on any cycle within each second),
an I/O link access-overload soft failure is generated. The soft failure is reset when an
overrun does not occur for eight seconds.

For each cycle, the current hour and previous hour I/O link access-overrun counters are
maintained in the APMM and displayed on the UCN Detailed Status Displays to help track
down the cause of the overrun.

UCN Access Overrun—This type of overrun occurs when parameter read or write access
requests to other APMs (or other nodes) on the same UCN are not completed within the
given time (0.75 seconds).

When this type of access overrun occurs, the UCN access-overrun counter is incremented
by 1, but point processing is not delayed. The sequence programs that access data from
other UCN devices remain suspended until a response becomes available (or a
communication timeout occurs). For input connections at RegPV, RegCtl, and logic slots
that require data from the UCN, the last fetched value is used until new data becomes
available, or a time-out occurs.

If the UCN access overrun occurs for 8 seconds in a row (on any cycle within each second),
a UCN access-overload soft failure is generated. The soft failure is reset when an overrun
does not occur for 16 seconds.

For each subcycle, the current hour and previous hour UCN access-overrun counters are
maintained in the APMM and appear on the UCN Detailed Status Displays to help track
down the cause of the overrun.

Peer-to-peer UCN Overruns and Soft Failures—Two consecutive peer-to-peer timeouts

are required to count as a UCN overrun. More than one UCN overrun in 8 consecutive
seconds causes a soft failure. The soft failure automatically clears when 16 consecutive
seconds do not contain any UCN overruns.

APM Control Functions & Algorithms 3-7 12/03

 3.1.3
Figure 3-1 illustrates the APM Scheduling Display—You may want to check this display
for overruns, especially if your process module points contain a large number of statements
per step (as long as all of the sequences in a subcycle average out to 20 statements per step,
no overruns will occur).

This display can be accessed through the APM Status Display/Detail Display target; then
under CONTROL CONFIGURATION, choose SCHEDULE INFO.

DD MMM YY HH:MM:SS 02

CONTROL CYCLE 1 CYCLE 2 CYCLE 3 CYCLE 4

CONFIG 1a 1b 2a 2b 3a 3b 4a 4b
From-To From-To From-To From-To From-To From-To From-To From-To
PV 020-006 005-003
Fast PV 002-001 002-001 002-001 002-001
PM 010-003 002-001
LOG 025-014 013-002
Fast Log 001-001 001-001 001-001 001-001
DV
Fast DV
DC 075-061 060-003
Fast DC 002-001 002-001 002-001 002-001
Ctl 050-044 043-030 029-017 016-003
Fast Ctl 002-001 002-001 002-001 002-001
Tim 064-001
Flg
128-001
Overruns:
CurHr PPX 00000 00000 00000 00000 00000 00000 00000 00000
PreHr PPX 00000 00000 00000 00000 00000 00000 00000 00000
CurHr IOL 00000 00000 00000 00000
PreHr IOL 00000 00000 00000 00000
UCN 003 P/S PRIMARY UCN CHANNEL CHANNELA FILE POS LEFT
NODE 005 STATUS OK UCN AUTO SWAP ENABLE
TYPE APM

Figure 3-1 — APM Scheduling Display

Along the left side, the type of point and execution order appears. The four 1/4 second
cycles and their subcycles divide the display into columns. The numbers in each column
represent the point slots. All of the points in a subcycle run consecutively in descending
order (compare to the drawing in 3.1.2.3). Overruns (if any) for the point processing
executive (PPX) and the I/O Link (IOL) appear across the bottom for the cycle or subcycle
affected.

APM Control Functions & Algorithms 3-8 12/03

 3.1.4
3.1.4 Performance Monitoring
Use the Toolkit displays to check various performance statistics. These displays show the
number of nodes requesting and responding, and the percent of time the APM
Communications and Controller CPUs are not busy. They also show the maximum,
minimum, and average request/response times for transactions between peer nodes and
other statistics. Section 10 of the Engineer’s Reference Manual explains how to use the
Toolkit displays.
A peer-to-peer communication efficiency statistic is displayed on the Control Configuration
page of the APM Detail Display. Also refer to the APM Implementation Guidelines for
other performance information.
3.2 DATABASE CONSIDERATIONS
The point mix and the scan rate are configured as a part of the APM Box Data Point. On the
Universal Station, this is the Node Specific Configuration display. When the APM Box
Data Point information is loaded into the APMM, the point mix is validated against the
absolute maximum allowed for each point type and the available memory and the scan rate
is validated against the available processing resources. The APMM box state must be IDLE
to make any changes to the point mix and scan rate configuration.
If changes are not required in the point mix, the APM Box Data Point can be loaded while
in the RUN state. For example, a new I/O Processor can be added without interrupting
control by simply loading the APM box data configuration (with the new I/O Processor
added) while in the RUN state.

CAUTION
When the point mix or the scan rate is changed, the database of all the slots is defaulted to a
null configuration and the database requires reconfiguration.

Point building follows box Configuration. Each point is configured to run in a slot inside
the APMM. The first time through a power-up cycle (APMM box state transition from
ALIVE to IDLE), the database of each slot (included in the default point mix) is defaulted
to a null configuration. The user can build or load a point configuration into each slot.
When a point is deleted, the database of the slot containing the point is defaulted to the null
configuration.
3.3 POINT EXECUTION STATE
Slot processing in the APMM is performed only when the APMM box state is RUN. Only
those slots whose point execution state (PTEXECST) is Active are processed. The point's
execution state must be Inactive in order to modify any of the configuration parameters (for
example, engineering unit range, PV or control algorithm ID, input/output connections,
etc.). When a point is made Inactive, all the calculated variables (like PV, CV, alarms, etc.)
are set to their default values ("NaN" for real numbers and OFF for Logical). The point
execution state cannot be changed back to Active until all the configuration parameters are
specified.

APM Control Functions & Algorithms 3-9 12/03

 3.3
3.3.1 Run-Idle-Run Transition
When the APMM is switched from RUN to IDLE and back to RUN, the affect on data
points is shown by the following:

Table 3-1 — Effect of Run-Idle-Run Transition

Effect of RUN to IDLE to RUN Transition
Logic Blocks Execution halts, then resumes once box is running again.
CL Programs Execution stops. Program needs to be restarted once PM is running
again. Refer to parameter RSTROPT.
Timers The timer stops and needs to be restarted once the box is running.
Time accumulation starts from where it left off unless reset
deliberately.
Other Point Types Processing stops and outputs are held. Processing resumes when
the APM is running again.

3.3.2 Warm/Cold Restart

The APM is started through the APM Status display. Warm/Cold startup refers to the
behavior of algorithms under initialization. When going from the idle to run state, the
operator can choose between warm and cold startup (for each APM). After a checkpoint
restore, either a warm or cold startup is possible.
Cold startup — this usually requires operator intervention, that is, the operator must
change some point states from manual to their normal operating mode. On a cold
startup, all Regulatory Control points that output to the field go to manual mode. For
Regulatory Control points that drive other Regulatory Control points (even in another
APM), a cold start does not cause a change from the previous mode.
Warm startup — If you choose warm startup, Regulatory Control points remain in the
previous mode and are back-initialized for a bumpless transfer to automatic control with
their previous output value.
Powerup Restart — If RAM memory was not lost since the previous operation, a
powerup restart is possible without reloading the program. In this case, the APM will
return to its previous Idle/Run state. If the state is Run, all points behave as if a cold
restart was performed.
Some points behave differently during startup regardless of the startup mode:
Regulatory PV Totalizer points — you can configure the point to continue or stop
accumulation on restart (see parameter PVEQN).
Process Module point — you can configure sequence execution to restart from the
beginning or remain off and be restarted by the operator (see parameter RSTROPT).
Regulatory Control Ramp Soak — Point is always set to Manual mode.

APM Control Functions & Algorithms 3-10 12/03

 3.3.2

Table 3-2 summarizes the important status conditions for Warm/Cold restart functions.

Table 3-2 — Warm Cold Restart

Point Type Parameter Status After Status After Status After

Power Off/On Cold Start Warm Start

Regulatory Control MODE Manual Manual Last Mode.

(except Ramp/Soak) Back-initializes;
Outputs to IOP goes on control

Regulatory Control MODE Manual Last Mode1 Last Mode.

(except Ramp/Soak) Back-initializes;
Outputs to another goes on control
RegCtl point

Regulatory Control MODE Manual Manual Manual

Ramp Soak

Regulatory PV PV Cont. Totalizing NaN Cont. Totalizing

Totalizer2 PVSTS Uncertn Bad Uncertn
PVEQN = A, B, C STATE Running Stopped Running

Regulatory PV PVSTS Bad Bad Bad

Totalizer
PVEQN = D, E, F STATE Stopped Stopped Stopped

Process Module SEQEXEC Run Run Run

RSTROPT = Restart PROCMOD Norm Norm Norm

SEQEXEC Loaded Loaded Loaded

Process Module PROCMOD Off Off Off
RSTROPT = Off

Timer PV Last Good Value3 Last Good Value3 Last Good Value3
STATE Stopped Stopped Stopped

1. Control is halted by the final point in the cascade which always outputs to an IOP.
2. Count may be inaccurate if rollover occurs in IOP.
3. The last good value can come from PM RAM Memory if battery power was continuously
available; otherwise, from the last checkpoint stored on the History Module.

APM Control Functions & Algorithms 3-11 12/03

 3.4

3.4 PEER-TO-PEER COMMUNICATION

Peer-to-peer communication allows information to be passed between devices on the UCN

and can be initiated from the Advanced Process Manager, the High-Performance Process
Manager, the Process Manager, the Logic Manager, or the Safety Manager.

3.4.1 Implementation

The APM provides the following two convenient mechanisms for implementing peer-to-
peer communications functions:
• Input/Output Connection
• CL Read/Write Statement

Both communication mechanisms offer location-independent access to data from another

UCN device using the "Tagname.Parameter" notation.

Refer to Table 3-3 for a summary of peer-to-peer communications.

Characteristics and configuration limits for input/output connection for each access are
described below.

• Input Connections—The RegPV, RegCtl, DevCtl, and Logic slots can use standard
input connections to obtain data from other UCN devices. When such a connection is
configured, it is scanned at the rate of twice per second, regardless of the scan rate of
the slot in which it is configured. The data obtained is saved internally and used (more
than once if the slot is running faster than twice a second) until the next time that it
needs data. Peer-to-peer data is requested .75 seconds before it is needed. The data
obtained from another UCN device can therefore be up to .75 second old by the time it
is used. A maximum of 50 input connections can be configured for each APMM.

We recommend that input connections be used for continuous peer access that requires
a 1/2 second update (see Table 3-3).

• Output Connections—The RegCtl, DevCtl, and Logic slots can use standard output
connections to provide outputs to other UCN devices. Output connections are processed
when the slot is processed, thus outputs are updated four times per second, two times
per second, or once per second depending on the point processing rate. The number of
output connections per APMM is not limited.

We recommend that output connections be used for regulatory-control cascades

between UCN devices (see Table 3-3).

APM Control Functions & Algorithms 3-12 12/03

 3.4.1

Table 3-3 — Peer-to-Peer Summary

Peer-to-Peer Configuration Limits Handling of Failure/Recovery Recommended
Mechanism (Per APM) of Peer Node Usage

Input 50 values per 1/2 Analog —On failure, bad value Use for continuous
Connections second (NaN) is substituted. (1/2 second) update
Digital - Addressed by Logic of data required for
Slot. On failure, ON, OFF, RegPV, RegCtl,
or last value is substituted DevCTL, or Logic
based on user configuration. Slots.
On recovery from failure,
accessed values are then
used.

Output Not limited Regulatory control cascade — Use for regulatory

Connections primary initializes. control cascades
Logic output —store does not between nodes.
occur.
On recovery from failure, regu-
latory control clears initializa-
tion and resumes control.
Subsequent output changes
are stored on transition.

CL Read 16 values per If requested read transaction Use for on-demand

Statement Process Module not completed, CL program data required by CL
Data Point branches to specified programs. Use for
per second error location. Program fails continuous
when error option not used. (1 second) update of
On failure recovery, program data required for
behavior is based on user RegPV, RegCtl,
code, or requires operator DevCTL, or Logic
interaction if failed. Slots.

CL Write 16 values per Same as above. Same as above

Statement Process Module Note: Use of Read
Data Point or Write statements
per second is based on user
preference.

Characteristics and configuration limits for CL/APM read/write peer access are as follows:

• CL/APM Program—A user-written CL/APM sequence program executing in the

APMM can use explicit read/write statements to read parameter values from other UCN
devices and write parameter values to other UCN devices. Any time a read/write
statement is executed, the sequence program is suspended until the following cycle
when the response becomes available (normally one second).

We recommend that the CL read/write technique be used for on-demand peer access,
and for continuous peer access that requires a 1-second update.

APM Control Functions & Algorithms 3-13 12/03

 3.4.2

3.4.2 Restrictions

Certain restrictions exist on the type of data that can be accessed through peer-to-peer
communication. These restrictions vary with the point type. Table 3-4 shows the type of
data that can be accessed for each point type or connection type.

Table 3-4 — Peer-to-Peer Communications

Connection Type Allowed Data

RegCtl.CISRC No restrictions
RegCtl.CODSTN RegCtl.SP only

RegPV.PISRC No restrictions

Logic.LISRC No restrictions
Logic.LODSTN No restrictions
DevCTL.LISRC No restrictions
DevCTL.LODSTN No restrictions

DigComp No Peer-to-peer connections allowed

DevCtl No Peer-to-peer connections allowed

ProcModl Read Statement No restrictions

ProcModl Write Statement No restrictions

In addition to the configuration constraints described above, there are performance-related

limits on parameter access that affect the overall peer-to-peer throughput capability. Actual
performance for each APM varies depending on specific system configuration; however,
any APM should be capable of handling a total load of up to 400 parameters per second.

In addition to the above parameter throughput-related constraint, the number of devices

concurrently communicating to a single Advanced Process Manager is another factor that
influences performance.

The interaction of the above constraints must be considered primarily in applications in

which an extreme communication load is continuous. In this type of application, the
following configuration recommendations maximize peer-to-peer throughput capability:

• Adopt a single approach for all peer-peer communications; use either input/output
connections or CL read/write statements. If a 1-second update is adequate and cascade
interconnection is not required, the CL read/write approach offers increased capability
(quantity/throughput) for peer data access.
• For CL read/write approach, consistently use same method (either CL reads or CL
writes).
• For CL read/write approach, the Process Module Data Points that are continually
affecting peer-to-peer communication should be grouped on the same 1/4-second cycle.

APM Control Functions & Algorithms 3-14 12/03

 3.5
3.5 HARDWARE REFERENCE ADDRESSING

The APM allows the referencing of parameters of I/O points (AO,DI, DO) on a hardware
basis within the same APM using the standard input/output hardware connection reference
syntax (user-written sequence programs can reference DI points). This type of addressing
does not affect the point count in the NIM and these “untagged” references can be quickly
built, but there are several disadvantages. Untagged points are not easily visible in the
system so you must use the Command Processor Find Names function to see the
connections. Note that operating displays cannot include untagged points.

The use of untagged references is not recommended, however, there might be a reason to
use them or some may be present in an existing system. If you use them keep good records.

The hardware reference address point format is

!MTmmSss.Parameter

where: MT is the IOP type such as AO, DI, DO, or PI,

mm is the number of the IOP card (1-40) in the card file,
ss is the input or output slot number on the specified IOP card.
Parameter is the parameter whose value is to be written to by an output
connection, or a parameter whose value is to be read by an input connection.
The following are examples of hardware reference addresses:*
AO Processor Output ==> !AO12S03.OP
= parameter OP
of Slot #3
of AO Processor #12

DI Processor PV ==> !DI05S07.PVFL

= parameter PVFL
of Slot #7
of DI Processor #5

DO Processor (Status or Latched) Output ==> !DO15S12.SO

= parameter SO
of Slot #12
of DO Processor #15

DO Processor ON Pulse Command ==> !DO15S12.ONPULSE

= parameter ONPULSE
of Slot #12
of DO Processor #15

DO Processor OFF Pulse Command ==> !DO15S12.OFFPULSE

= parameter OFFPULSE
of Slot #12
of DO Processor #15

Standard status displays are available to show which points are associated with each hardware
module.
____________________
*The AI address !AImmSss.Parameter is not supported because the analog input point does
not have a useable default database.

APM Control Functions & Algorithms 3-15 12/03

 3.5.1
3.5.1 Find Names Function
You can use the Find Names function to provide the node number, module type, point type,
and slot number for all connections. This function is especially helpful to find the hardware
reference points. Refer to the Command Processor manual for information on the Find
Names utility.

3.6 REDUNDANCY
The APM can contain optional redundant APMM modules and certain types of optional
redundant IOP modules (currently HLAI, STIM, and AO modules). During APM Node
Specific configuration, the user specifies which modules are redundant and, for IOPs, the
file/card locations of the redundant partners. Refer to Section 2 in the Advanced Process
Manager Implementation Guidelines manual for more information.
If a redundant APMM module or synchronized redundant IOP module fails, switchover is
automatic and transparent to the user (input and set output operations are unaffected). Data
acquisition, alarming, and control strategies are automatically managed by the system.
The principal parameters that pertain to APM redundancy are—
ACTPRIM IOMFILEA/B POSITION
FTACONN IOREDOPT SYNCHSTS
IOMCARDA/B PKGOPT WITHBIAS
Refer to these parameters in the Advanced Process Manager Parameter Reference
Dictionary for additional information.

3.7 POINT RESERVATION

To support batch applications, you need to be able to reserve certain points that represent
shared devices for particular batches. The APM allows CL programs to reserve Regulatory
Control, Regulatory PV, Logic, Digital Composite, Device Control, Process Module, and
Array points for exclusive use.
Point reservation is accomplished using a 16-character string parameter (USERID). This
string has special logic so that two programs cannot reserve the same point at the same
time. This string can always be stored by the operator, but a program can only store a
nonblank string when the USERID itself is currently blank. This should eliminate race
conditions.
To keep programs from failing, storing an invalid string does not generate an error; it will
just not do anything. The program should read the string back after the store to verify that it
was accepted. To handle retries, a given value of the string can be stored any number of
times. All blanks can be stored at any time to release the point. Programs must be careful
not to release points that other programs or the operator have reserved. A special string
starting with three or more dashes may be used to indicate that a point cannot be reserved
and only the operator can clear this string.

APM Control Functions & Algorithms 3-16 12/03

 3.8

3.8 STATUS MESSAGES

The Status Message function is available for RegCtl, RegPV, Logic, DigComp, DevCtl,
ProcMod, and Array points. One table of messages is configurable for each NIM.

During UCN Node Configuration for the NIM, you can enter up to 15 Message Text Items,
(MSGTXT(n)). The entry is an 8-character ASCII string. Message text item 0 defaults to
NONE and is not configurable. The actual number of Message Text items that you can enter
is determined by parameter NMSGTXT, the number of Message Text items.

On the point’s Detail display, the operator can select STSMSG and choose any message
from the table of Message Text items that appears. That Message Text item then replaces
the current contents of STSMSG and, if nothing of higher priority is currently displayed,
appears as a comment at the lower left of the display. The Status Message also appears in
place of the “Red Tag” message when Red Tag is on.

If a point is not in Red Tag, a CL program can store a message (in STSMSG). When Red
Tag is on, only the engineer or supervisor can store the message.

APM Control Functions & Algorithms 3-17 12/03

APM Control Functions & Algorithms 3-18 12/03
 4

DIGITAL COMPOSITE POINT

Section 4

This section describes the functions available in the digital composite point. The description of the
output portion of the point is provided first, followed by the description of the input portion. Definitions
of the parameters mentioned in this section can be found in the Advanced Process Manager
Parameter Reference Dictionary.

4.1 DESCRIPTION
The digital composite point is a multi-input/multi-output point that provides an interface to
discrete devices such as motors, pumps, solenoid valves, and motor-operated valves. This
point provides built-in structures for handling interlocks, and supports display of the
interlock conditions in group, detail, and graphic displays. In addition, the digital composite
point can be used with logic slots and other digital points to implement complex interlock
schemes.
Some of the features of the digital composite point are as follows:
• Input and output states of the data point are totally independent of each other and can be
configured as required by the user's application. The inputs and outputs of the point can
be linked to I/O points or to Boolean flags within the APM.
• Supports devices with two or three commandable states (motor-operated valves,
reversing motors, etc.). Specific states can be defined as being momentary.
• Provides structured approach to handling interlock functions and includes indication to
the operator of existence of interlock condition.

4.2 POINT STATES

4.2.1 Normal States
A digital composite point can have two or three normal states that allow the data point to
interface with devices that have two or three operational states. The states of a digital
composite point are as follows:
• State 1—this is the first active state.
• State 0—this is the inactive (middle) state. This is considered a safe state. If for any
reason a valid output cannot be determined, the OP is forced to this state. See
subsection 4.9 which discusses initialization manual.
• State 2—this is the second active state. (State 2 is applicable only when the entry for the
NOSTATES parameter is 3, signifying that the data point has three states.)

APM Control Functions & Algorithms 4-1 12/03

 4.2.1
These states can best be described by showing how the digital composite data point is
depicted in a Universal Station group display, as shown in Figure 4-1. On the display,
each state is represented by a separate box. The state 0 box is the middle box, the state 1
box is the upper box, and state 2 box is the lower box. (The state 2 box does not appear if
the point has been configured for two states where parameter NOSTATES = 2). The state
descriptor for each box is an 8-character descriptor and appears at the top of the box. In
Figure 4-1, the descriptors are FORWARD (for state 1), STOP (for state 0), and REVERSE
(for state 2), which are specified by parameters STATETXT(0)-STATETXT(2).
The lower portion of each box is split, with the left box being the indicator for the input PV
state, and the right box being the commanded-output state indicator. The condition of the
PV input that causes the left box to light is determined by parameters D2D1_00 - D2D1_11.
The condition that causes the right box to light is determined by OP being commanded to
that state.

State 1 Descriptor
STATETXT (1)
FORWARD
State 1 Box

PVState 1 Indicator OP State 1 Indicator (Commanded State)

PVFL (1)

State 0 Descriptor
STOP STATETXT (0)
State 0 Box

PVState 0 Indicator
OP State 0 Indicator (Commanded State)
PVFL (0)

State 2 Descriptor
REVERSE STATETXT (2)
State 2 Box

PV State 2 Indicator OP State 2 Indicator (Commanded State)

PVFL (2)
Double Bar in Output
State indicator shows
that this state cannot
be commanded

Figure 4-1 — Digital Composite Point Display 11010

APM Control Functions & Algorithms 4-2 12/03

 4.2.2

As an example, assume that the digital composite point shown in Figure 4-1 is connected
through digital output points and digital input points to a motor control circuit and that the
current state of the digital composite point is state 0 (STOP).

• In state 0, the PV indicator of the STOP box is lit, indicating that the motor is stopped
because the proper PV input has been received from the field. All other indicators in the
display are in the extinguished condition.

• When the operator touches the FORWARD box to place the motor in the forward
running direction, the digital composite point output goes to State 1. Outputs from the
digital composite point are provided as determined by the ST1_OPn parameter (where
n=1..3). When the proper PV inputs are received from the field, the FORWARD box is
lighted. This indicates to the operator that the motor is running. Also, the current state
of the PV can be read by a logic slot or by a user program by accessing parameter
PVFL(n) where n is 0, 1, or 2. If the PV is in State 0, PVFL(0) is on; otherwise,
PVFL(0) is off. PVFL(1) and PV(FL2) operate in the same manner for States 1 and 2,
respectively.

• Similarly, when the operator presses the STOP box, the operator is notified that the
motor is stopped by the lighted PV indicator in the STOP box. The operator can then
select the REVERSE box to start the motor running in the reverse direction.

4.2.2 Momentary States

The states of a digital composite point can be configured as being momentary by using the
MOMSTATE parameter. The commanded states can be configured as momentary where
the state acts like a doorbell (state remains active as long as a switch is pressed). The
momentary states (MOMSTATE) parameter specifies which of the states are momentary as
follows:

Entry Description

Mom_1 State 1 is momentary. When released from this state, it jumps back to State 0.

Mom_0 State 0 is momentary. When released from this state, it jumps back to State 1.
Mom_0 can be selected only if the NOSTATES parameter = 2.

Mom_2 State 2 is momentary. When released from this state, it jumps back to State 0.
Mom_2 can be selected only if NOSTATES parameter = 3.

Mom_1_2 States 1 and 2 are momentary. When released from any one of these states, it back
jumps to State 0. Mom_1_2 can be selected only if NOSTATES parameter = 3.

A state cannot be set to momentary if the MOMSTATE parameter = NONE. MOMSTATE

is mutually exclusive with the Seal-In option or State Change option (STCHGOPT).

APM Control Functions & Algorithms 4-3 12/03

 4.2.3

4.2.3 Moving/Bad States

The digital composite point has two standard states that represent conditions when the
current state of the device is "bad" (indeterminate) or the current state is "moving" (from
one state to another). The bad state can result when the PV input signals from the process
are in an inconsistent state (e.g., for a valve, the limit switches indicating open and closed
are both simultaneously on). The moving state is encountered when the device is in
transition from one state to another (e.g., a slow moving valve is changing from the open
state to the closed state). The moving/bad state descriptor is located below the State 2 box
on the display. In the example described above, the descriptor assigned for the BADPVTXT
parameter would be the word FAULTY and the descriptor assigned for the MOVPVTXT
parameter would be the word MOVING. These descriptors are configured once for each
APM box data point and then are used for all digital composite points in the same APM.

If the standard "bad/moving" default text is not desired, you can select the PV Text Option
during point configuration, and enter two eight-character strings of your choice. While the
words "bad/moving" are defined on a PM/APM box basis, your entries override them on a
per point basis. Up to 15 unique bad/moving text descriptors can be defined on a UCN
network basis.

4.3 MODE ATTRIBUTES

The digital composite point supports only the manual (MAN) mode with mode attributes
(specified by parameter NMODATTR) of Operator and Program. If the mode attribute is
Operator, only the Universal Station operator can provide the commanded output state, as
shown in Figure 4-2. On the other hand, if the mode attribute is Program, only user
programs (continuous or discontinuous) can provide the commanded output state. The
operator mode attribute flag (OPRATRFL) is also provided for potential use by the
interlocking logic.

The MODEPERM parameter is provided to optionally prevent the operator (as opposed to
the supervisor or engineer) at the Universal Station from changing the mode attribute.

APM Control Functions & Algorithms 4-4 12/03

 4.4
4.4 INTERLOCKS

Two kinds of interlocks, permissives and overrides, are provided in the output portion of a
digital composite point. The states of the interlocks are typically controlled by output
connections from logic slots that can write to the P0-P2 permissive interlock parameters,
and I0-I2 override interlock parameters. In addition, a safety override interlock (SI0) that
cannot be bypassed is provided.

4.4.1 Permissive Interlocks

The permissive interlock parameters P0-P2 shown in Figure 4-2 are controlled by logic slot
outputs, and the permissive interlocks determine whether the operator and user programs
are allowed to change the output of a digital composite point to a specific state. A
permissive interlock is provided for each of the three states. The permissive interlocks
themselves never cause the output to change.

For the commanded output to be changed to the desired state, the corresponding permissive
interlock parameter must be set to ON. As an example, if a logic-slot output has set
parameter P1 to OFF, the commanded output of the digital composite point cannot be set to
State 1. The permissive interlock parameters P0, P1, and P2 are all defaulted to ON, thereby
allowing permission for all the states. They must be individually set to OFF by the logic
slots to prevent access to the corresponding commanded output state.

4.4.2 Override Interlocks

The override interlock parameters I0-I2 shown in Figure 4-2 are also controlled by the logic
slot outputs and can force the commanded output to a specific state regardless of the
condition of the permissive interlocks. The operator and user programs cannot change the
output state when any override interlock is in the ON condition. An override interlock is
provided for each of the three output states.

When parameter I0 is set to ON by a logic slot output, the commanded output state is forced
to State 0 (regardless of the condition of parameters I1 and I2). When I0 is OFF and I1 is
ON, the commanded output is forced to State 1 (regardless of parameter I2). Finally, when
I0 and I1 are OFF and I2 is ON, the commanded output is forced to State 2.

Override interlock parameters I0-I2 are all defaulted to OFF, disabling all the override
interlocks. They must be set to ON to force the output to go to any specific state. If the
override interlock forces the output to go to a momentary state, it stays in that state as long
as the interlock remains ON and then switches back to the original state when the override
interlock is reset to Off.

When all the override interlocks are OFF, the last value of the commanded output is
maintained (except for momentary state) until changed by the operator, a user program, or
another override interlock. The interlock logic restores the output value to the output
devices (Digital Output IOPs) whenever the interlock value changes, even if the state
asserted by the interlock is already in effect.

APM Control Functions & Algorithms 4-5 12/03

 4.4.2
The Override Alarm Option (OVRDALOP) allows an Optional alarm to be generated when
an override occurs. You have the following configuration choices for the Override Alarm
Option:
1. no alarm
2. return to normal when the override is cleared (auto return)
3. operator confirmation required after interlock is cleared (the operator must
confirm the alarm before it is possible to command a new state).
The occurrence of a new override takes precedence over any previously active override
(including the Safety Override Interlock, SIO) if that condition has returned to inactive.
Therefore, to the operator, a lower priority confirmation appears to overwrite a higher
priority override if that higher priority override has reset. This is sometimes called an auto-
confirm of the previous override.
If a higher priority override has been reset, the descriptions and confirm prompt (if
Cnfm_Rqd was configured) remain visible until the operator confirms the override from the
Detail Display. The confirm prompt and alarm are then reset. If any other override occurs
after a previous condition has reset, regardless of the previous priority, the new description
and confirm prompt appear. This also applies to the Real Time Journal Display. If the
confirmation required option was not selected for a particular class of overrides, the
description will still override the previous one and the previous confirm prompt goes away,
if the previous override condition has reset.

NOTE
For those upgrading from R400 to R510 and later systems, note the differences
described in this section and make sure your strategy still works as intended.
In R410 and R510 or later systems, a lower priority interlock (such as I1) can
become active if a higher priority interlock (such as I0) is no longer true but has
not yet been confirmed. In R400 systems, Confirmation has to be done before the
lower priority interlock is activated.

When the Digital Composite point is built, you can specify the tag name of the Logic point
that is driving the interlocks as parameter LOGICSRC. The contents of this parameter then
appear on the Group Display when the Digital Composite point is selected. After
identifying the Logic point, an operator can call up the Detail Display for that point to find
out about the interlocks.
You can predefine an eight character alarm descriptor for each override interlock, I0-I2.
When the override interlock is activated, that string is displayed on the detail display. CL
programs can write into these descriptors (InDESC) before asserting the interlock. The
detail display text then explains why the program forced the interlock (e.g., TOO HOT in
the Override Alarm Descriptor, OVRDDESC).

APM Control Functions & Algorithms 4-6 12/03

 4.4.2
Operator
Commanded State Off
(OP) from Operator Off

On On
Commanded State NMODATTR OROPT BYPASS
(OP) from Program
Program

Commanded
STATE 2 State STATE 1

STATE 0
Permissive
Interlocks ON ON ON
(P1, P0, & P2 are OFF P2 OFF P0 OFF P1
controlled by
Logic Blocks)

STATE 2 STATE 0 STATE 1

ON OFF
STATE 2 I2
Override
Interlocks
(I2, I1, & I0 are
controlled by ON OFF
Logic Blocks) STATE 1 I1

ON OFF
STATE 0 I0

OFF
Safety ON
Interlock STATE 0 SI0

Output Connections
(Up to 3 Outputs)
PULSEWTH OUTPUT STxOPy
STCHGOPT STATE STxOPy
SEALOPT GENERATOR
MOMSTATE (OPFINAL) STxOPy
x = 0, 1, 2
y = 1, 2, 3 2100

Figure 4-2 — Digital Output, Functional Diagram 2100

APM Control Functions & Algorithms 4-7 12/03

 4.4.3

4.4.3 Configurable Interlock Bypass

The operator can have the ability to bypass the permissive and override interlocks for a
digital composite point. To do so, the override parameter OROPT must be set to ON. The
operator can then set (or reset) the parameter BYPASS from the Universal Station. Note
that while BYPASS is ON, the point execution state parameter can’t be changed. When the
BYPASS parameter is reset, existing override interlocks (if any) take effect immediately.
The group display shows whether interlocks are being bypassed. The organizational
summary display lists all the points for which BYPASS = ON.

4.4.4 Safety Interlocks for State 0 (SI0)

The safety override interlock parameter SI0 behaves like the I0 interlock, but it cannot be
bypassed even when BYPASS is configured and turned on (see Figure 4-2).

If a device has tripped as a result of a state 0 interlock, an interlock-trip alarm (SI0ALOPT)

can result (if configured). The interlock-trip alarm has three options: None (no alarming),
Auto Return or Alarm with Confirm Required. The alarms are described as follows:

• Auto Return— if a state 0 interlock causes the OP state to change, an interlock-trip

alarm is generated and then automatically terminated when the interlock, that caused
the alarm returns to OFF.

• Alarm with Confirm Required— if a state 0 interlock causes the OP state to change,
an interlock-trip alarm is generated. The interlock that caused the alarm must return
to OFF and the operator must reset the trip-confirm required flag OVRDCONF. The
trip-confirm required flag can also be reset by REDTAG, BYPASS, or
LOCALMAN, but the motor cannot be restarted by the operator, interlock, or other
system functions until the interlock trip alarm is terminated.

• If SIO resets, a lower priority interlock can be asserted and confirm automatically as
described in subsection 4.4.2.

You can predefine an 8-character alarm descriptor for SIO. When the safety override
interlock is activated, that string is displayed on the detail display. CL programs can write
into these descriptors (InDESC) before asserting the interlock. The detail display text then
explains why the program forced the interlock (e.g., TOO HOT in the Override Alarm
Descriptor, SIODESC). SIOALPR sets the interlock-trip alarm priority.

Trip Descriptor—When a device trips because of an interlock, the cause of the trip is
available as an 8-character descriptor from the parameter OVRDDESC.

APM Control Functions & Algorithms 4-8 12/03

 4.5

4.5 COMMANDED STATE (OP)

The command to go to a specific state results in outputs to the process that drive the actual
state of the device to the commanded state. The commanded state is represented by the OP
parameter in the digital composite point; the commanded state can be State 1 (ST1), State 0
(ST0), or State 2 (ST2). The OP parameter is available for configuration only if the number
of digital output connections (NODOPTS) is configured to be greater than 0.

Up to nine Boolean parameters of the form STx_OPy (where x = 0, 1, or 2 for the state
number and y = 1, 2, or 3 for the output number) allow the user to specify the state values
that are to be stored by the output connections. For each of the three commanded states per
output connection, the user must define the value (On or Off) of the state.

CL programs or Logic points can test the parameter INITREQ to see if they are allowed to
command a certain state. If INITREQ(i) = ON, then CL programs or Logic points cannot
change the output to STATE(i) (i = 0, 1, or 2).

The Status Output command parameter allows Logic points or CL programs (APM or AM)
to manipulate outputs (subject to interlocks and the mode attribute). Logic or CL programs
can set SOCMD(i) to ON to command State(i) where I = 0, 1, or 2. The same rules apply as
storing the corresponding state to the OP parameter, i.e., the mode attribute must be
PROGRAM, the corresponding permissive must be available, no override can be active,
etc. The actual output (OP) is switched to the requested state only by an OFF to ON change
of the corresponding SOCMD(i) flag. There is no priority scheme; the last one changing
from OFF to ON controls the output.

OP can be commanded to state 1 or state 0 using the OPCMD parameter. When OPCMD is
ON, OP is set to state 1. When OPCMD is OFF, OP is set to State 0. OPCMD can be used
when three states are defined, but will only command OP to state 1 or state 0. Overrides
take precedence over OPCMD; however, when the override is cleared, the OP will be
commanded to the state determined by OPCMD. OPCMD should not be used in
conjunction with SOCMD since OPCMD will always override the state set by SOCMD.
Like SOCMD, OPCMD only affects OP when the mode attribute is PROGRAM.

CAUTION
Do not configure two different logic outputs to drive OPCMD and SOCMD of the same Digital
Composite Point.

APM Control Functions & Algorithms 4-9 12/03

 4.5

Seal-In Circuit—the seal-in circuit is a configurable option (SEALOPT). It is used to

unlatch the digital output contacts on detection of the PV, not following the output
command as happens on a device drop out (e.g., a stopped motor).

This condition is determined to be true any time the PV is not in state1 or state 2 and either
of the following is present

• a command disagree alarm

• an uncommanded state change alarm

If the seal-in option is enabled, when the above condition is detected, the output
destinations are set to the state corresponding to OP of state 0, but OP is not altered. The
actual state commanded to the output destinations can be observed on the lower part of the
group display as OPFINAL. OPFINAL is displayed in reverse video if it is different from
OP. OPFINAL is set equal to OP on the next store to OP, thus clearing the seal condition.
However, if OPCMD is used, it must be set OFF, then ON to clear the seal condition.

Note that the seal-in option is mutually exclusive with MOMSTATE.

State Change Option—A configurable option (STCHGOPT) allows break before make on
output changes. You must configure state 0 as the break, or off, or inactive state. The
number of states must equal 3.

When an output change from state 1 to state 2 or from state 2 to state 1 is commanded—
• OP changes to state 0 first.
• if the command disagree time out alarm is configured and a corresponding PV state
is applicable, the alarm is held off until a successful feedback has been reached (i.e.,
PV = state 0).
• the digital composite point waits for a predefined pause time (PAUSETIM).
• OP is then changed to the requested value.

Example—if the break before make option is enabled, commanding a motor to change
direction from forward to reverse causes the motor to stop before reversing.

Note that the CL state change statement waits until feedback for the second OP change is
successfully received.

Note that the seal-in option is mutually exclusive with MOMSTATE.

APM Control Functions & Algorithms 4-10 12/03

 4.6

4.6 DIGITAL OUTPUTS

The user can specify the latched or pulsed output type for the digital composite point
through the configurable output connections.

4.6.1 Latched Output

Configuring the digital composite point for a latched output is accomplished by specifying
any parameter other than ONPULSE or OFFPULSE.

4.6.2 Pulsed Output

Configuring the digital composite point for a pulsed output is accomplished through the
output connections by specifying the ONPULSE or OFFPULSE parameters as the
destination points for the outputs. The width of the pulse is configured at the digital
composite data point through the PULSEWTH parameter; it allows the user to specify a
pulse width from 0 to 60 seconds as a real number. The selected pulse width applies to all
of the output connections.

4.7 OUTPUT CONNECTIONS

The destinations of the outputs (and the output types) from a digital composite point are
specified by the user through the DODSTN(1)-DODSTN(3) parameters. The categories of
destinations that can be specified are as follows:
• Digital Output Point—Latched Output
• Digital Output Point—Pulsed Output
• Logic Slot Flag
• APM Box Flag
• Process Module Slot Flag
• Device Control Slot Flag

• Array Point Flag (see also 10.3.5)

These destinations must be in the same APM box as the digital composite point that is
being configured.

APM Control Functions & Algorithms 4-11 12/03

 4.7.1

4.7.1 Digital Output Point—Latched Output

To assign the digital composite-point output to the latched output of a digital output point,
the user can enter either of the following output connections for the respective DODSTN(n)
output connection parameter:

Tagname.SO

or

!DOmmSss.SO

where: Tagname is the 8- or 16-character name assigned to the data point through
the NAME parameter.

SO signifies the status output of the digital output point.

!DO signifies a digital output point. This is the start of the hardware-reference
form of addressing the digital output.

mm is the IOP card number from 1-40 of the Digital Output IOP Card within
the same APM.

the letter ‘S’ is a constant.

ss is the slot number in the range from 1-16 on the same Digital Output IOP
Card.

4.7.2 Digital Output Point—Pulsed Output

Pulsed outputs can be either of two types: normally off pulsed-on, and normally on pulsed-
off. To assign the digital composite-point output to the pulsed output of a digital output
point, the user can enter the following information for the respective DODSTN(n) output
connection parameter:

For a normally off pulsed-on output:

Tagname.ONPULSE

or

!DOmmSss.ONPULSE

where: Tag Name is the 8- or 16-character name assigned to the data point through the
NAME parameter.
ONPULSE or OFFPULSE signifies the pulsed output of the digital output
point.

APM Control Functions & Algorithms 4-12 12/03

 4.7.3
For a normally on pulsed-off output:
Tagname.OFFPULSE

or

!DOmmSss.OFFPULSE

where: Tagname is the 8- or 16-character name assigned to the data point through the
NAME parameter.

ONPULSE or OFFPULSE signifies the pulsed output of the digital output

point.

Refer to paragraph 4.7.1 for descriptions of !DOmmSss

4.7.3 Logic Slot Flags

To assign the digital composite-point output to a logic-slot flag, the user can enter the
following information for the respective DODSTN(n) output connection parameter:

Tagname.FL(nn)

where: Tagname is the 8- or 16-character name assigned to the data point through the
NAME parameter.

FL signifies a logic-slot flag

nn is the flag number to which the output of the digital composite is sent. The
flag number has a range of 7-12: flag numbers 1-6 have dedicated uses and
cannot be used as destinations by a digital composite point.

4.7.4 APM Box PV Flags

To assign the digital composite-point output to an APM box PV flag in the same APM box,
the user can enter the following information for the respective DODSTN(n) output
connection parameter:

Tagname.PVFL or !BOX.FL(nnnn)

where: Tagname is the 8- or 16-character name assigned to the data point through the
NAME parameter.

PVFL signifies the PV flag

!BOX specifies the same APM box in which the digital composite point
resides.

nnnn is the flag number. Box flags from 1 to 16,384 are available.

APM Control Functions & Algorithms 4-13 12/03

 4.7.5
4.7.5 Device Control Slot Flags

To assign the digital composite-point input to a Device Control slot flag, the user can enter
the following information for the respective DISRC(n) input connection parameter:

Tagname.FL(nn)

where: Tagname is the 8- or 16-character name assigned to the data point through the
NAME parameter.

FL signifies a flag

nn is the flag number to which the input of the digital composite is sent. The
flag number has a range of 7-12: flag numbers 1-6 have dedicated uses and
cannot be used as destinations by a Device Control point.

4.7.6 Array Point Flags

To assign the digital composite-point input to an Array Point flag, the user can enter the
following information for the respective DISRC(n) input connection parameter:

Tagname.FL(nn)

where: Tagname is the 8- or 16-character name assigned to the data point through the
NAME parameter.

FL signifies a flag

nn is the flag number to which the input of the digital composite is sent. The
flag number has a range of 1-NFLAG, where NFLAG is the array point
parameter that defines the number of flags in the Array point.

4.8 READ-BACK CHECK

Digital Composite and Device Control points can have digital output connections through
an SI/Array point to a field device. The field device or its interface may interrupt or change
the output and not provide any indication of the change.

If flag data is mapped back from the SI/Array point, a digital output read-back check
determines the actual value of the output. After a new output state is stored to the digital
output connections, the read-back check is delayed for a time period equal to the feedback-
time parameter time (FBTIME) or 4 seconds, whichever is greater. This delay allows the
SI/Array output enough time to reach even a slow responding field device before causing a
Command Disagree alarm (see subsections 4.14 and 11.5).

If a discrepancy then exists between OPFINAL and OP, the operator is advised. If
OPFINAL does not agree with any of the defined states, its state is displayed as NONE.

APM Control Functions & Algorithms 4-14 12/03

 4.9

4.9 INITIALIZATION MANUAL

A digital composite point that has at least one output connected to a DO IOP is forced into
the initialization manual condition (INITMAN is On) when one of the following conditions
exists:
• The associated DO IOP has failed or been powered off (digital composite point cannot
communicate with the DO IOP), the DO IOP is in an idle condition, or in standby
manual, for the FTA is missing.
• The associated DO IOP has its initialization request (INITREQ) flag set. The flag may
be set because the point is inactive, the point is not configured as a status output type, or
one of the output diagnostics has failed.
• The digital composite point is inactive.
• The APMM is in an idle condition.

INITMAN is displayed at the Universal Station for the particular digital composite point to
inform the user that one of the above conditions has occurred. When the condition is
corrected, INITMAN is set to Off.
When INITMAN transitions from On to Off, the digital composite point provides an output
value OP as follows:
• If override interlocks are active and not bypassed, the OP value corresponds to the
highest priority override interlock.
• Otherwise, in cases where feedback is configured, the stored OP value tracks the PV
state if the PV state is valid (that is, not bad or moving).
• Otherwise, (if the input is bad) the OP value is back-initialized from the output
connections if there are no output connections to the ONPULSE/OFFPULSE
parameters, and if a valid OP value can be constructed from the values of the output
connections. For output connections to ONPULSE or OFFPULSE, OP is set to
State 0.
• Otherwise, the OP is set to State0.

4.10 DIGITAL INPUTS

When configuring digital inputs of the digital composite data point, the user can specify the
input connections, PV states, PV source and options, alarming, and change-of-state events.
The input portion of a digital composite point can be configured only if the user has entered
1 or 2 for the number-of-digital-inputs parameter (NODINPTS). A functional diagram of
the input portion of the digital composite point is shown in Figure 4-3.

APM Control Functions & Algorithms 4-15 12/03

 4.11

4.11 INPUT CONNECTIONS

The inputs to a digital composite point are specified by the user through digital input-source
parameters DISRC(1)-DISRC(2). Inputs to the digital composite point are designated as
Input 1 and Input 2, and they can be obtained from any of the following sources:

• Digital Input Point—PV

• Digital Output Point—SO
• Logic Slot Output
• Logic Slot Flag
• APM Box Flag PV
• Process Module Slot Flag
• Array Slot Flag
• Device Control Slot Flag

These sources must be in the same APM box as the digital composite point that is being
configured.
The status of Input 1 is represented by parameter D1; Input 2 is represented by parameter
D2. Input 2 can be configured only when the entry for the number-of-digital-inputs
parameter (NODINPTS) is 2.

4.11.1 Digital Input Point—PV

To assign the PV of a digital input point to the PV input of a digital composite point in the
same APM box, the user can enter the following information for the respective DISRC(n)
input connection parameter:

Tagname.PVFL
or
!DImmSss.PVFL

where: Tagname is the 8- or 16-character name of the point that will provide the PV.
· PVFL signifies the PV of the respective digital input point.
· !DI signifies a digital input point. This is the start of the hardware reference address.
· mm is the Digital Input IOP Card number from 1-40 within the same APM.
· the letter “S” is a constant.
· ss is the slot number in the same Digital Input IOP Card in the range from 1-32.

APM Control Functions & Algorithms 4-16 12/03

 4.11.1

D1 CURRENT
INPUT1
INPUT STATE
INPUT2 D2 GENERATOR

PVAUTO

Current Output State

Track
Auto
PV (from Operator)
Man PVSOURCE

PV (from Program)
Sub
All OnlyAuto

PVSRCOPT
PV

BAD PV
BADPVFL
ALARMING

BADPVPR

Current Output State COMMAND

FBTIME > 0 DISAGREE CMDDISFL
CMDDISPR ALARMING

COMMAND CMDFALFL
CMDFALTM > 0
FAIL ALARM

PVNORMAL
< > None OFF-NORMAL OFFNRMFL
ALARMING
OFFNRMPR

UNCOMMANDED
UNCMDFL
CHANGE ALARM
15017

Figure 4-3 — Digital Input, Functional Diagram 15017

APM Control Functions & Algorithms 4-17 12/03

 4.11.2

4.11.2 Logic Slot Output

To assign the logic slot output to the PV input of a digital composite point, the user can
enter the following information for the respective DISRC(n) input connection parameter:

Tagname.SO(nn)

where: Tagname is the 8- or 16-character name assigned to the logic slot that is
providing the output.

SO signifies the output of the logic block.

nn is the logic block number in the range from 1-24

4.11.3 Logic Slot Flags

To assign a logic slot flag to the input of a digital composite point, the user can enter the
following information for the respective DISRC(n) input connection parameter:

Tagname.FL(nn)

where: Tagname is the 8- or 16-character name assigned to the logic slot that is
providing the flag.

FL signifies the logic-slot flag

nn is the flag number in the range from 1-12.

4.11.4 APM Box PV Flags

To assign a APM box PV flag to the input of a the digital composite point, the user can
enter the following information for the respective DISRC(n) input connection parameter:

Tagname.PVFL

or

!BOX.FL(nnnn)

where: Tagname is the 8- or 16-character name assigned to the box PV flag

PVFL signifies the PV flag

!BOX specifies the APM box.

FL(nnnn) is the flag number that has a range from 1 to 16384.

APM Control Functions & Algorithms 4-18 12/03

 4.11.5

4.11.5 Device Control Slot Flags

To assign the digital composite-point output to a Device Control slot flag, the user can enter
the following information for the respective DODSTN(n) output connection parameter:

Tagname.FL(nn)

where: Tagname is the 8- or 16-character name assigned to the data point through the
NAME parameter.

FL signifies a flag

nn is the flag number to which the output of the digital composite is sent. The
flag number has a range of 7-12: flag numbers 1-6 have dedicated uses and
cannot be used as destinations by a Device Control point.

4.11.6 Array Point Flags

To assign the digital composite-point output to an Array Point flag, the user can enter the
following information for the respective DODSTN(n) output connection parameter:

Tagname.FL(nn)

where: Tagname is the 8- or 16-character name assigned to the data point through the
NAME parameter.

FL signifies a flag

nn is the flag number to which the output of the digital composite is sent. The
flag number has a range of 1-NFLAG, where NFLAG is the array point
parameter that defines the number of flags in the Array point.

4.11.7 Process Module Slot Flags

To assign a Process Module slot flag to the input of a digital composite point, enter the
following information for the respective DISRC(n) input connection parameter:

Tagname.FL(nn)

where: Tagname is the 8- or 16-character name assigned to the Process Module flag

FL(nn) signifies the flag

APM Control Functions & Algorithms 4-19 12/03

 4.12

4.12 CURRENT INPUT STATE (PV)

The flexibility of the digital composite point allows the user to assign the states of the PV
for each possible combination of digital inputs, so that the states correspond to the different
applications in which this point type can be used. The PV parameter represents the current
state of the interfaced device and is derived from inputs D1 and D2 that can be feedback
signals from the process. Separate parameters are used to configure a single-input point and
a dual-input point.

NOTE
The inputs to a digital composite point are usually the PVs from digital input points. The
digital input points should be configured as component points that force the input direction
to be direct (as opposed to reverse). The actual direct/reverse action can be configured by
assigning the appropriate PV state to the input as described in the following paragraphs.

For a single-input point, there is only one input parameter (D1). D1 has two possible PV
states (PVstate0 and PVstate1) that can be assigned to either of the following input
conditions:

D1 = 1 (D1 is ON; parameter D1_1)

D1 = 0 (D1 is OFF; parameter D1_0)

The user has to assign only PVstate0 or PVstate1 to parameter D_1; the system
automatically assigns the other PV state to parameter D1_0.

For a dual-input point, there are two input parameters (D2 and D1) that together have four
possible combinations of input values as follows:

D2D1 = 00 (D2 is OFF, D1 is OFF; parameter D2D1_00)

D2D1 = 01 (D2 is OFF, D1 is ON; parameter D2D1_01)
D2D1 = 10 (D2 is ON, D1 is OFF; parameter D2D1_10)
D2D1 = 11 (D1 is ON, D2 is ON; parameter D2D1_11)

APM Control Functions & Algorithms 4-20 12/03

 4.13

To these four combinations of input values, the user can assign any four of the following
five PV states:

Pvstate1
Pvstate0
Pvstate2
MovPV
BadPV

PVstates1, 0, and 2 cause the PV indicator to be lighted in the respective state box on the
group display when the assigned D2D1 input conditions are satisfied. The MovPV and
BadPV states cause the respective MOVPVTXT or BADPVTXT descriptor to appear
below the state boxes on the group display.

4.13 PV Source

The PV source parameter (PVSOURCE) determines the source of the current PV state for
the digital input portion of the digital composite data point. The possible sources of the
current PV state are as follows:

Source Description

Man (Manual) Current PV state is provided by the operator from the Universal Station.

Auto (Automatic) Current PV state is derived from Input 1 (D1) and Input 2 (D2).

Track Current PV state is the commanded output state

Sub (Substituted) Current PV state is provided by a user program

4.13.1 PV Source Option

During configuration, the user can specify the PV sources that can be used for this data
point. Parameter PVSRCOPT allows the user to select the PV source as being only AUTO,
or to select all the PV sources in the above listing as allowable sources of the PV. Note that
the organizational summary display lists all the points for which PVSOURCE =
TRACK.

APM Control Functions & Algorithms 4-21 12/03

 4.14
4.14 ALARMING
The digital composite point can be configured to detect and report command disagree,
command fault, uncommanded change, or off-normal alarms. The user has the option of
specifying no alarming for the data point. Digital composite points also generate a bad PV
alarm when any input is coming from a digital input point that has a bad PV flag
(BADPVFL) status of ON.
During the command disagree timeout interval, determined by the feedback-time parameter,
FBTIME, it is possible, in some instances, that the state defined as BADPV could occur in
the PV inputs, but not reflect an actual failure of the inputs or associated hardware. To
lessen operator confusion, these "state" BADPVs should be ignored. Therefore, only
BADPVs resulting from detected input errors are declared by the point during the timeout
interval. If a "state" BADPV occurs, the previous PV remains displayed.
These alarm options can be configured only if the digital composite point is configured to
have inputs, or inputs and outputs. The BADPVPR parameter determines priority of the bad
PV alarm.
4.14.1 Command Disagree, Command Fail, and Uncommanded Change
When the commanded-output state is changed and the actual input PVstate does not change
accordingly within a predefined feedback time, a command disagree alarm is generated.
The feedback time (1 to 1000 seconds) is specified by the FBTIME parameter and the timer
starts whenever the OP value changes. A command disagree alarm is also generated if OP
changes are caused by the interlocks.
This alarm condition returns to normal when the input PV state and the commanded-output
state are the same. If the commanded state is momentary, no alarm is generated. For
example, a motor may have two PV states (RUN and STOP), but there may be three
commanded output states (RUN, STOP, and JOG) where JOG is defined as a momentary
state. Command-disagree alarming is performed for only the RUN and STOP commanded
output states.
The command fail alarm is similar to the command disagree alarm, but instead of waiting
for the actual state to equal the commanded state, a check is made to verify that the PV
changed from its original value to any other value within a configurable time interval. For
slow devices, absence of this alarm provides feedback that the device responded to the
command, even if it has not yet moved to its final position. The command fail alarm is
enabled by entering an integer greater than zero for the command failure timeout parameter,
CMDFALTM.

If a change does not occur in the commanded output state but the input PV state changes
(and the PV is not bad), an uncommanded-change alarm is generated. This alarm condition
returns to normal when the input PV state and the commanded state are the same. If the
point state has been configured as being momentary, this type of alarm is not applicable.
Alarm priority for the command disagree alarm, the command fail alarm, and the
uncommanded change alarm is determined by the Command Disagree Priority
(CMDDISPR) parameter.

APM Control Functions & Algorithms 4-22 12/03

 4.14.2

4.14.2 Off-Normal
Detection of off-normal alarms is configured by selecting an FBTIME greater than zero.
The normal state of the PV input is defined by the user through the PVNORMAL
parameter.
When the PV input state is different than the state specified by the PVNORMAL parameter,
the off-normal alarm is generated. The alarm condition returns to normal when the PV input
state and the specified PV normal state are the same. When command disagree is
configured, the off-normal alarm is inhibited if PVNORMAL = OP. This is to avoid two
alarms at the same time and help isolate failures. You can set the priority of the off-normal
alarm with the OFFNRMPR parameter.

4.15 CHANGE-OF-STATE EVENTS

Any transitions in the PV input state can be reported as events for journaling and for
causing the event-initiated processing of points in the Application Module (AM). It is
configured by entering EIP for the event-report-option parameter EVTOPT. The user must
enter the tag name of the AM or CM point using the EIPPCODE parameter. If only
journaling is required, the EIPPCODE parameter can be set to a null tag name.

4.16 LOCAL MANUAL INDICATION

Field devices that are interfaced by a digital composite point often have a local
HAND/OFF/AUTO (often called HAND/OFF/REMOTE) switch. Unless this switch is in
AUTO position, the control system (APM) may not have any control over that device. The
user can optionally feedback the switch position into the APM to obtain some display
indication for the Universal Station operator. This indication is provided by the word
LOCALMAN appearing at the bottom of the digital composite point on a group display.
Further, when in local manual, any changes to the output by the operator, and user
programs, are prohibited. The override interlocks are still active when the local manual
condition is on. When the local manual condition is on, both OP and OPFINAL follow the
PV value (the actual state of the device).
To support HAND/OFF/AUTO switches, a Boolean flag called LOCALMAN is provided.
The ON state indicates that the switch is not in AUTO position. The user can hard-wire the
AUTO position of the HAND/OFF/AUTO switch through a digital input point. The state of
the digital input state is then stored to the LOCALMAN flag from logic slot outputs or
sequence programs.

APM Control Functions & Algorithms 4-23 12/03

 4.17

4.17 MAINTENANCE STATISTICS

The Maintenance Statistics page of the Digital Composite Point Detail Display provides
statistical information about the point. For example—

• accumulated number of transitions to each state

• date/time of most recent statistics reset
• accumulated time in each state
• date/time of most recent change to each state
• accumulated number of safety interlock overrides

Statistics are enabled by entries in the Maintenance Statistics section during point
configuration. You can enter the maximum number of hours that you want to allow in each
state and maximum number of transitions that you want to allow into each state. Even if
either maximum is reached, the Digital Composite point does not provide an alarm, but a
CL program can be written to monitor the statistics and take action.

4.17.1 Reset and Redtag

The above statistics are accumulated since the most recent reset. A program can reset the
statistics with the RESETFL parameter anytime or they can be reset from the Maintenance
Statistics page as explained below.

The Maintenance Statistics display contains a REDTAG target. The REDTAG and RESET
targets work as follows:
If you select the REDTAG target (and ENTER), the point’s REDTAG parameter is set to
ON and a RESET target appears. Selecting the RESET target (and ENTER), resets the
points maintenance statistic values. If you select REDTAG (and ENTER, the REDTAG
condition clears and the RESET target disappears.

APM Control Functions & Algorithms 4-24 12/03

 5

LOGIC POINT
Section 5

This section defines the functions available in the logic point. Definitions of the parameters
mentioned in this section can be found in the Advanced Process Manager Parameter Reference
Dictionary.

5.1 FUNCTIONS

The logic point provides a configurable mix of logic capability that, together with a digital
composite point, provides the basis for integrated logic functions. The logic point is also
fully integrated with the regulatory functions in the APM. A logic point consists of logic
blocks, flags, numerics, user-defined generic descriptors, input connections, and output
connections as shown in Figure 5-1.

5.2 CONFIGURING THE LOGIC POINT

The logic point can have up to 12 input connections, 24 logic blocks, and 12 output
connections. The actual number of these is specified through the entry made for LOGMIX
parameter as shown in the following chart:

LOGMIX No. of Input No. of Logic No. of Output

Param. Entry Connections Blocks Connections

12_24_4 12 24 4

12_16_8 12 16 8

12_8_12 12 8 12

5.2.1 Logic Input Connections

Inputs to the logic point are assigned by the user during configuration by using logic input
connections. The user can specify up to 12 inputs that are assigned to logic-point inputs
L(1) to L(12), as shown in Figure 5-1. The logic input connections can be specified using
the "Tagname.Parameter" format, or the hardware reference address format by using the
LISRC parameter.

APM Control Functions & Algorithms 5-1 12/03

 5.2.1
The inputs to the logic point can be obtained from any of the following sources:
• Any Boolean, integer, enumeration, self-defining enumeration, or real parameter within
this APMM or in another UCN node. Note that the integer, enumeration, or self-
defining enumeration parameters are automatically converted to real values.
• The PV flag parameter (PVFL) of a DI point from a DI IOP in this APM.
• The Bad PV flag parameter (BADPVFL) of a DI point from a DI IOP in this APM.
• The Status Output parameter (SO) from a DO point in this APM.
• The Initialization Request flag (INITREQ) from a DO point in this APM.
• Any parameter other than the DI point's PVFL from the IOPs in this APM. Maximum of
four such input connections can be configured (these follow the same kind of
restrictions that CL/APM has for prefetches).

GENERIC DESCRIPTORS

PARMDESC (1) DESCTEXT (1)

: :
PARMDESC (12) DESCTEXT (12)

LOGIC INPUT LOGIC BLOCKS LOGIC OUTPUT

CONNECTIONS CONNECTIONS

SO (1)
LISRC (1) L (1) LOGALG (1) LOSRC (1) LODSTN (1)
:
: : LOENBL (1) :
:
:
: :
SO (24) LOSRC (12) LODSTN (12)
LISRC (12) L (12) LOGALG (24)

LOENBL (12)

NUMERICS FLAGS

NN (1) . . NN (8) = User FL (1) = Always OFF.

Set FL (2) = Always ON.
FL (3) = Point Activation.
FL (4) = PMM Startup.
FL (5) = At Least One Bad LI.
FL (6) = Watchdog Reset Flag.
FL (7) . . FL (12) = User Set.

Figure 5-1 — Logic Point 11011

APM Control Functions & Algorithms 5-2 12/03

 5.2.1
5.2.1.1 Effect of Communication and Configuration Errors on Logic Input Connections

Because the logic point can be used for implementing safety interlocks, special handling is
provided for inputs, especially Boolean inputs, that cannot be obtained because of
communication or configuration errors.
For example, an input obtained from a failed DI Processor can result in a communication
error. Alternatively, an input can be coming from a digital composite point in another APM
(or PM) and the point mix in that APM can be changed such that the specified point no
longer exists. This results in a configuration error. In order for the logic to be able to
continue in spite of a configuration error, the following special features are provided:
• Bad Boolean Inputs—If a Boolean input is not successfully fetched, its value is
defaulted based on the logic input bad handling option parameter (LIBADOPT) as
follows:
LIBADOPT = On The On state is substituted for the unsuccessful input.
LIBADOPT = Off The Off state is substituted for the unsuccessful input.
LIBADOPT = Hold The previous value (the last successfully fetched value) is
substituted for the unsuccessful input. On startup, the previous
value is defaulted to the Off state. If required, the startup
condition can be monitored by checking the startup flag.
• Bad Real Inputs—If a real input cannot be successfully fetched, its value is defaulted to
NaN. If required, special action can be taken in the logic by checking it with the "check
for bad" logic algorithm.
• Input Bad Flag—When an error is encountered in fetching the value of any input, flag
FL(5) is set to On. Note that flag FL(5) is not set to On if a real input is successfully
fetched but has a value of NaN.
• Processing Order—The logic points defined for each APM are processed in decending
order. Within each logic point, the inputs are calculated first, then the gates are
processed, then the outputs are processed, each in ascending order.
5.2.2 Flags
Twelve flags, FL(1) to FL(12), are provided for each logic point. The states of flags FL(1)
to FL(6) are controlled by the APM and cannot be changed by the user. Flags FL(7) to
FL(12) are assigned by the user for controlling the path of the logic in the respective logic
point.

APM Control Functions & Algorithms 5-3 12/03

 5.2.3
The flags are described in the following listing:
Flag Description

FL(1) Always Off (but see 5.2.5 when used for logic output enable).
FL(2) Always On.
FL(3) On only if this logic point is processing for the first time after becoming
active.
FL(4) On only if this point is processing for the first time after the APMM box
state has transitioned from Idle to Run, or the APMM has gone into the
Run state following a power-up.
FL(5) On if at least one of the logic input connections was unsuccessful in
fetching the specified source parameter.
FL(6) Used by the watchdog timer logic algorithm. It is set to On by the
function or device being monitored to indicate that it is alive. The
watchdog timer algorithm always sets this flag to Off. Flag FL(6) cannot
be changed from the Universal Station.
FL(7)-FL(12) Can be changed as determined by the user. They can be changed from the
Universal Station, other logic points, or user programs.
Flags FL(1) to FL(5) cannot be changed by the user, but the states of these flags can be used
as inputs to the logic points and can also be read by user programs.

5.2.3 Numerics
Eight numerics, NN(1) to NN(8), are provided with each logic point. The numerics can be
used as reference values for the comparison logic algorithms, or they can be used as source
parameters for the output connections when writing predefined analog constants to other
points. The values of the numerics can be changed from the Universal Station, by other
logic points, or by user programs. A bad numeric input typically has the value NaN.

5.2.4 Logic Blocks

The logic operations in a logic point are performed by the logic blocks. Up to 24 logic
blocks can be configured by the user for each logic point. The actual number of logic blocks
configured is determined by the logic mix described in paragraph 5.2. Each logic block
consists of

• Up to 4 inputs (specified by S1, S2, S3, S4.)

• One logic algorithm (specified by LOGALG)
• One Boolean output (specified by SO)

APM Control Functions & Algorithms 5-4 12/03

 5.2.5

The parameters associated with a logic block are always qualified with an array index
corresponding to the number of that logic block. For example, LOGALG(4) represents the
algorithm configured in the logic block number 4, whose output is SO(4), and the inputs
may be S1(4), S2(4), etc.

On the first time through configuration, the outputs of all logic blocks are set to OFF;
however, on a subsequent restart (for example: IDLE to RUN transition of the APMM
state, or INACTIVE to ACTIVE transition of the point execution state), all the outputs are
held at their previous values.

Processing Order—The logic points defined for each APM are processed in descending
order. Within each logic point, the inputs are calculated first, then the gates are processed,
then the outputs are processed, each in ascending order.

5.2.5 Output Connections

Logic output connections are used to write the values of local parameters of a respective
logic point to the configured destinations. Up to 12 output connections can be configured
for each logic point. The actual number of output connections is determined by the
LOGMIX parameter described in paragraph 5.2. The destinations are specified by parameter
LODSTN by using the "Tagname.Parameter" format or the hardware reference address
format.

The logic output connection can write the selected local parameters of a logic point to any
of the following destinations:

• Any Boolean, integer, enumeration, self-defining enumeration, or real parameter in this

APMM, or another UCN node

• Any Boolean, integer, enumeration, self-defining enumeration, or real parameter in the

IOPs in this APM. A maximum of eight such connections can be configured for each
point. The remaining four output connections can be used to write to boolean or real
parameters that reside in this APMM or in another UCN node.

The user must specify the local parameter within the logic point and the destination to
which it is to be written. The local parameter to be written is specified as the logic output
source (LOSRC(n), where n = 1 to 12). The source parameter for the output connection can
be selected from any of the flags (specified as FL1, FL2, etc.), numerics (specified as N1,
N2, etc.), external inputs (specified as L1, L2, etc.), or the output of any of the logic blocks
(specified as SO1, SO2, etc.).

APM Control Functions & Algorithms 5-5 12/03

 5.2.6

Associated with each output connection is a logic output enable flag, LOENBL(n). The
parameter pointed to by LOENBL(n) must be ON for the corresponding output connection
to write to the specified destination. If store-only-on-a-change is required, the appropriate
condition to store can be determined by the CHDETECT logic algorithm and then used to
manipulate the enable signal; or if the FL1 parameter is specified for the output enable and
the output data type is Boolean, then output occurs on change only. The logic output enable
flag can be obtained from any of the flags (specified as FL1, FL2, etc.), external inputs
(specified as L1, L2, etc.), or the output of any of the logic blocks (specified as SO1, SO2,
etc.).

5.2.6 Generic Descriptors

Up to 12 user-defined generic descriptors are provided with each logic point for identifying
parameters of the logic point with custom names that are to be shown on Universal Station
displays. Generic descriptors can be assigned to any of the following logic-point
parameters:
• Flags (FL1, FL2, etc.)
• Numerics (N1, N2, etc.),
• External inputs (L1, L2, etc.),
• Outputs of any of the logic blocks (SO1, SO2, etc.).
Typically, the generic descriptors identify critical interlock signals, operator-adjusted
parameters, etc.

The actual number of descriptors used is determined by the NODESC parameter for this
logic point. For each descriptor, the parameter to which it is attached is defined by
PRMDESC(n) parameter, and the corresponding 8-character descriptor is defined by
GENDESC(n).

5.3 LOGIC BLOCK ALGORITHMS

Logic blocks perform logic functions. Each logic block can have up-to-four inputs and
produce a single Boolean output, depending on the selected algorithm. The algorithm can
require real or Boolean inputs. The real inputs can be obtained from any of the numerics
(specified as NN1, NN2, etc.) or the external inputs (specified as L1, L2, etc.). The Boolean
inputs can be any of the flags (specified as FL1, FL2, etc.), external inputs (specified as L1,
L2, etc.), or the output of any of the logic blocks (specified as SO1, SO2, etc.).

When one of the external inputs (L(1), L(2), .. L(12)) is used as an input to an algorithm,
the value fetched can be real or Boolean. If the algorithm requires a real input and the
fetched value is Boolean, it is treated as NaN. If the algorithm requires a Boolean input and
the fetched value is real, it is treated as OFF. In either case, the bad input flag, FL(5), is not
affected.

APM Control Functions & Algorithms 5-6 12/03

 5.3

The following logic block algorithms are supported:

• Null (NULL)
• AND Gate (AND)
• OR Gate (OR)
• NOT Gate (NOT)
• NAND Gate (NAND)
• NOR Gate (NOR)
• XOR Gate (XOR)
• Qualified OR Gate With 2 Inputs ON (QOR2)
• Qualified OR Gate With 3 Inputs ON (QOR3)
• Switch (SWITCH)

• Compare Equal With Deadband (EQ)

• Compare Not Equal With Deadband (NE)
• Compare Greater Than With Deadband (GT)
• Compare Greater Than or Equal With Deadband (GE)
• Compare Less Than With Deadband (LT)
• Compare Less Than or Equal With Deadband (LE)

• Check for Bad (CHECKBAD)

• Fixed Size Pulse (PULSE)

• Pulse With Maximum Time Limit (MAXPULSE)
• Pulse With Minimum Time Limit (MINPULSE)
• Delay (DELAY)
• On Delay (ONDLY)
• Off Delay (OFFDLY)

• Watchdog Timer (WATCHDOG)

• Flipflop (FLIPFLOP)

• Change Detect (CHDETECT)

APM Control Functions & Algorithms 5-7 12/03

 5.3.1

5.3.1 Null (Null)

This logic algorithm provides an output (SO) that is always set to OFF.

5.3.2 AND Gate (AND)

This algorithm provides a 3-input AND gate, with each input (S1, S2, and S3) having the
capability of being optionally inverted, as required. The output SO is determined as follows:

S1

S2 AND SO

S3

SO = (((S1REV = OFF) AND (S1 = ON)) OR ((S1REV = ON) AND (S1 = OFF)))
AND
(((S2REV = OFF) AND (S2 = ON)) OR ((S2REV = ON) AND (S2 = OFF)))
AND
(((S3REV = OFF) AND (S3 = ON)) OR ((S3REV = ON) AND (S3 = OFF)))

REV = indicates if the input signal is reverse acting.

5.3.3 OR Gate (OR)

This logic algorithm provides a 3-input OR gate, with each input (S1, S2, and S3) having
the capability of being optionally inverted, as required. The output SO is determined as
follows:

S1

S2 OR SO

S3

SO = (((S1REV = OFF) AND (S1 = ON)) OR ((S1REV = ON) AND (S1 = OFF)))
OR
(((S2REV = OFF) AND (S2 = ON)) OR ((S2REV = ON) AND (S2 = OFF)))
OR
(((S3REV = OFF) AND (S3 = ON)) OR ((S3REV = ON) AND (S3 = OFF)))

APM Control Functions & Algorithms 5-8 12/03

 5.3.4

5.3.4 NOT Gate (NOT)

This algorithm provides the Boolean inversion (NOT) function. The output SO is the
inversion of the input S1 as follows:

S1 NOT SO

IF (S1 = ON) THEN SO = OFF

ELSE SO = ON

5.3.5 NAND Gate (NAND)

This algorithm provides a 3-input NAND gate, with each input (S1, S2, and S3) having the
capability of being optionally inverted. The output SO is determined as follows:

S1

S2 NAND SO

S3

SO = NOT ( (((S1REV = OFF) AND (S1 = ON)) OR ((S1REV = ON) AND (S1 = OFF)))
AND
(((S2REV = OFF) AND (S2 = ON)) OR ((S2REV = ON) AND (S2 = OFF)))
AND
(((S3REV = OFF) AND (S3 = ON)) OR ((S3REV = ON) AND (S3 = OFF))))

APM Control Functions & Algorithms 5-9 12/03

 5.3.6

5.3.6 NOR Gate (NOR)

This logic algorithm provides a 3-input NOR gate, with each input (S1, S2, and S3) having
the capability of being optionally inverted. The output SO is determined as follows:

S1

S2 NOR SO

S3

SO = NOT ( (((S1REV = OFF) AND (S1 = ON)) OR ((S1REV = ON) AND (S1 = OFF)))
OR
(((S2REV = OFF) AND (S2 = ON)) OR ((S2REV = ON) AND (S2 = OFF)))
OR
((S3REV = OFF) AND (S3 = ON)) OR ((S3REV = ON) AND (S3 = OFF))))

5.3.7 XOR Gate (XOR)

This algorithm provides a 2-input exclusive-OR gate. The output SO is determined as

follows:

S1

XOR SO

S2

SO = NOT (S1 = S2)

APM Control Functions & Algorithms 5-10 12/03

 5.3.8

5.3.8 Qualified OR Gate with 2 Inputs ON (QOR2)

This algorithm provides a 4-input qualified-OR function that requires at least two inputs to
be ON before output SO is set to ON. The output is determined as follows:

S1

S2
QOR2 SO
S3

S4

IF (at least 2 inputs out of S1, S2, S3, and S4 are ON) THEN
SO = ON
ELSE
SO = OFF

5.3.9 Qualified OR Gate with 3 Inputs ON (QOR3)

This algorithm provides a 4-input qualified-OR function that requires at least three inputs to
be ON before output S0 is set to ON. The output is determined as follows:

S1

S2
QOR3 SO
S3

S4

IF (at least 3 inputs out of S1, S2, S3, and S4 are ON) THEN
SO = ON
ELSE
SO = OFF

APM Control Functions & Algorithms 5-11 12/03

 5.3.10

5.3.10 Switch (SWITCH)

This algorithm provides a 2-input switch. Output SO is determined as follows:

S3

S1

SWITCH SO
S2

IF (S3 = ON) THEN

SO = S1
ELSE
SO = S2

5.3.11 Compare Equal with Deadband (EQ)

This algorithm compares two real inputs (R1 and R2) for being "almost equal" or within a
specified deadband. Output SO is determined as follows:

R1

R2
EQ SO

DEADBAND

IF (ABS(R1 - R2) <= DEADBAND) THEN

SO = ON
ELSE
SO = OFF

If R1 and/or R2 inputs are "NaN", then SO is not changed.

APM Control Functions & Algorithms 5-12 12/03

 5.3.12

5.3.12 Compare Not Equal with Deadband (NE)

This algorithm compares two real inputs for NOT being "almost equal," or being outside of
a prespecified deadband. Output SO is determined as follows:

R1

R2
NE SO

DEADBAND

IF (ABS(R1 - R2) > DEADBAND) THEN

SO = ON
ELSE
SO = OFF

If R1 and/or R2 inputs are NaN, S0 is not changed.

5.3.13 Compare Greater Than with Deadband (GT)

This algorithm compares a real input (R1) for being greater than another real input (R2)
with a predefined deadband. Output SO is determined as follows:

R1

R2
GT SO

DEADBAND

IF (R1 > R2) THEN

SO = ON
ELSE IF (R1 <= (R2 - DEADBAND)) THEN
SO = OFF
ELSE
SO is not changed.

If R1 and/or R2 inputs are NaN, S0 is not changed.

APM Control Functions & Algorithms 5-13 12/03

 5.3.14

5.3.14 Compare Greater Than or Equal with Deadband (GE)

This algorithm compares a real input (R1) for being greater than or equal to another real
input (R2) with a specified deadband. Output SO is determined as follows:

R1

R2
GE SO

DEADBAND

IF (R1 >= R2) THEN

SO = ON
ELSE IF (R1 < (R2 - DEADBAND)) THEN
SO = OFF
ELSE
SO is not changed.

If R1 and/or R2 inputs are NaN, SO is not changed.

5.3.15 Compare Less Than with Deadband (LT)

This algorithm compares a real input (R1) for being less than another real input (R2) with a
predefined deadband. Output SO is determined as follows:

R1

R2
LT SO

DEADBAND

IF (R1 < R2) THEN

SO = ON
ELSE IF (R1 >= (R2 + DEADBAND)) THEN
SO = OFF
ELSE
SO is not changed.

If R1 and/or R2 inputs are NaN, SO is not changed.

APM Control Functions & Algorithms 5-14 12/03

 5.3.16

5.3.16 Compare Less Than or Equal with Deadband (LE)

This logic algorithm compares a real input (R1) for being less than or equal to another real
input (R2) with a predefined deadband. Output SO is determined as follows:

R1

R2
LE SO

DEADBAND

IF (R1 <= R2) THEN

SO = ON
ELSE IF (R1 > (R2 + DEADBAND)) THEN
SO = OFF
ELSE
SO is not changed.

If R1 and/or R2 inputs are NaN, SO is not changed.

5.3.17 Check for Bad (CHECKBAD)

This logic algorithm checks a real input (R1) for being bad (equal to NaN). Output SO is
determined as follows:

R1 CHECKBAD SO

IF (R1 is "NaN") THEN

SO = ON
ELSE
SO = OFF

APM Control Functions & Algorithms 5-15 12/03

 5.3.18

5.3.18 Fixed-Size Pulse (PULSE)

This logic algorithm provides a fixed-size output pulse at the SO output each time the S1
input transitions from the OFF state to the ON state. The output pulse width (in seconds) is
specified by the DLYTIME parameter. If the delay time is less than or equal to one sample
time (of the logic point), it is assumed to be equal to one sample time. Another output pulse
cannot be generated until the generation of the preceding pulse has been completed.

DLYTIME

S1 PULSE SO

S1

DLYTIME DLYTIME

SO
11021

APM Control Functions & Algorithms 5-16 12/03

 5.3.19

5.3.19 Pulse with Maximum Time Limit (MAXPULSE)

This logic algorithm provides a pulse at the SO output each time the S1 input transitions
from the OFF to the ON state. If the input stays ON longer than a predefined time, the
output pulse is terminated. The maximum output pulse width (in seconds) is specified by
the DLYTIME parameter. If the specified output pulse width is less than or equal to one
sample time (of the logic point), it is assumed to be equal to one sample time.

DLYTIME

S1 MAXPULSE SO

S1

DLYTIME DLYTIME

SO

APM Control Functions & Algorithms 5-17 12/03

 5.3.20

5.3.20 Pulse with Minimum Time Limit (MINPULSE)

This algorithm generates a pulse at the SO output each time the S1 input transitions from
the OFF to the ON state. If the S1 input stays ON for an interval that is less than the
specified time, the output pulse is extended until the timed interval is over. The minimum
output pulse width (in seconds) is specified by the DLYTIME parameter. If the specified
output pulse width is less than, or equal to, one sample time (of the logic point), it is
assumed to be equal to one sample time.

DLYTIME

S1 MINPULSE SO

S1

DLYTIME DLYTIME

SO

5.3.21 Delay (DELAY)

This logic algorithm delays the input signal at the S1 input by one sample time. The SO
output always follows the input after one sample time delay.

S1 DELAY SO

APM Control Functions & Algorithms 5-18 12/03

 5.3.22

5.3.22 On Delay (ONDLY)

This logic algorithm delays the input signal supplied at the S1 input when the input signal is
going from the OFF to the ON state. (There is no delay provided when the input changes
from the ON to the OFF state.) When the input state changes from OFF to ON, an internal
timer starts counting down the delay time specified by the DLYTIME parameter (in
seconds). When it times out, the S1 input is monitored again, and if it is still ON, the SO
output is set to ON. When the input state transitions to OFF, the SO output is set to OFF
immediately, and the timer is shut off (if it is running). If the specified delay time is less
than or equal to one sample time (of the logic point), it is assumed to be equal to one
sample time.

DLYTIME

S1 ONDLY SO

S1

DLYTIME DLYTIME

SO

APM Control Functions & Algorithms 5-19 12/03

 5.3.23

5.3.23 Off Delay (OFFDLY)

This logic algorithm delays the input signal supplied at the S1 input when the input signal is
going from the ON to the OFF state. (There is no delay provided when the input changes
from the OFF to the ON state.) When the input state changes from ON to OFF, an internal
timer starts counting down the delay time specified by the DLYTIME parameter (in
seconds). When it times out, the S1 input is monitored again, and if it is still OFF, the SO
output is set to OFF. When the input state transitions to ON, the SO output is set to ON
immediately, and the timer is shut off (if it is running). If the specified delay is less than or
equal to one sample time (of the logic point), it is assumed to be equal to one sample time.

DLYTIME

S1 OFFDLY SO

S1

DLYTIME DLYTIME

SO

5.3.24 Watchdog Timer (WATCHDOG)

This logic algorithm provides a "time out" capability to monitor other system functions or
remote devices. The function or device monitored must set the watchdog reset flag FL(6)
(of this logic point) to ON within a time interval specified (in seconds) by the DLYTIME
parameter, otherwise it is assumed to have failed, and the SO output of the algorithm is set
to ON. If the specified delay time is less than or equal to one sample time (of the logic
point), it is assumed to be equal to one sample time. When the watchdog timer algorithm
runs and if the FL(6) flag is ON, the internal timer is set equal to DLYTIME, and FL(6)
and the output SO are both set to OFF; however, if FL(6) is OFF, the internal timer is
decremented, and if it becomes zero, the SO output is set to ON. Because this algorithm
always uses the FL(6) flag of the logic point as the reset input, only one Watchdog Timer
algorithm should be configured for each logic point.

APM Control Functions & Algorithms 5-20 12/03

 5.3.25

5.3.25 Flip-Flop (FLIPFLOP)

This algorithm provides the flip-flop function. The SO output is determined by the states of
inputs S1 and S2 as follows:

S1

S2 FLIPFLOP SO

S3

S1 S2 SO
OFF OFF Not changed
ON OFF OFF
OFF ON ON
ON ON S3 input

5.3.26 Change Detect (CHDETECT)

This algorithm is used to detect changes in up-to-three inputs. The output SO is determined
as follows:

S1

S2 CHDETECT SO

S3

SO = (S1 < > S1_last_time)

OR
(S2 < > S2_last_time)
OR
(S3 < > S3_last_time)

APM Control Functions & Algorithms 5-21 12/03

 5.4

5.4 LOGIC BLOCK ALARMS

5.4.1 Configurable Alarms

Four custom alarms can be configured for each logic point. The alarm source can be any of
the logic inputs (L1–L12), logic flags (FL1–FL12), logic gate outputs (SO1–SO24), or
None.

When the alarm source is None, a CL program can force an alarm by writing ON to the
alarm flag (C1FL–C4FL) and clear the alarm by writing OFF to the alarm flag.

Each of the four custom alarms permits an 8-character descriptor that appears on page one
of the Detail Display, the Alarm Summery Display, and the Real Time Journal, when that
alarm is active.

The alarm priority choices are: No Action, Journal, Low, High, Emergency, Journal Print,
and Printer.

APM Control Functions & Algorithms 5-22 12/03

 6

PROCESS MODULE DATA POINTS

Section 6

This section describes the functions available in the Process Module Data Point and the associated
Box Flag, Box Numeric, and Box Timer Data Points. Definitions of the parameters mentioned in this
section can be found in the Advanced Process Manager Parameter Reference Dictionary.

6.1 PURPOSE OF THE PROCESS MODULE DATA POINT

Control strategies frequently need the flexibility of user programs for continuous, batch, or
hybrid applications. A Process Module Data Point is the resource for execution of user-
created programs written in Honeywell's Control Language (CL/APM). CL/APM is a
member of Honeywell's family of advanced process-engineer oriented languages and is a
powerful tool for advanced continuous control, sequential control, and computations. CL
programs are self-documenting, which is an important feature when future modifications of
control strategies are anticipated.

Total statement capacity depends on configuration. The maximum number of CL/APM

statements = 3(15000 - n) where n is the number of Memory Units used by data points (see
subsection 3.1.3). Using the Universal Station or the Universal Work Station, individual
programs can be easily modified and reloaded without affecting the execution of regulatory
control, logic blocks, and other user programs.
programs.

The Process Module Data Point is the interface between the system and a CL/APM
(sequence) program that resides in the Process Module Data Point. The Process Module
Data Point shown in Figure 6-1 is the mechanism through which

• An operator, a CL/AM block, a user-written CM program, or another sequence program

can start and stop a sequence program and monitor the current status of a sequence
program.

• Sequence alarms (sequence errors, failures, and phase alarms) are reported to the
system; an alarm priority can be assigned to sequence alarms.

• A sequence program can send information to an Advanced Control Point (ACP) in a

Computing Module when implementing high-level control strategies.

APM Control Functions & Algorithms 6-1 12/03

 6.1

PROCESS MODULE DATA POINT

PROCMOD
OVERPHAS SEQUENCE
OVERSTEP
CONTROL
OVERSTAT
ACP INTERFACE
BATCHID

LOCAL VARIABLES
SEQMODE CL/APM
SEQUENCE • 127 Flags
SEQNAME
PROGRAM • 80 Numerics
STATUS
PHASE • 16 Strings
STEP • Normal • 4 Times
INTERFACE Sequence
STATMENT
PHASETIM • Subroutines

• Abnormal
Condition
Handlers
ALPRIOR
ALARM
PHASEAL
INTERFACE
SEQERR

APM BOX DATABASE

Figure 6-1 — Process Module Data Point, Functional Diagram 11012

APM Control Functions & Algorithms 6-2 12/03

 6.1.1
6.1.1 CL/APM Sequence Program

To accomplish the desired sequence control, the sequence program can

• Monitor current process values such as temperatures, pressures, and flows and current
states of devices such as valves and motors. The sequence program can access values
from the local APM database, and from any other node such as APM, HPM, PM, LM,
or SM that is on the same UCN. A sequence program can read the values of almost all
parameters in the APM database except for character-string descriptors such as
PTDESC (Point Descriptor), and input/output connections.

• Control the process by using the accessed values to calculate new values and write them
to the appropriate parameters. The sequence program can write values into the local
APM database and into any other node such as APM, HPM, PM, LM, or SM that is on
the same UCN. A sequence program can write values to all parameters in the APM
database except for calculated variables such as alarm flags and general configuration
parameters such as PVALGID (PV Algorithm Identifier).

• Use the 127 local flag variables, the 80 local numeric variables, the 16 8-character string
variables and the 4 time variables that reside in each Process Module Data Point. The
string variables can alternatively be used as 8 16-character or 4 32-character or 2 64-
character strings. It can also use the local flags, numerics, strings and times that reside
in other Process Module Data Points. Additional flags, numerics, strings, time, and
timer variables reside in the APM Box (see Section 9) and are available to all sequence
programs in the same APM. CL programs cannot access APM Box variables with an
index of greater than 4,095. Array points can be used to refer to those variables (see
Section 10).

• Start another sequence program or force an abnormal condition in another Process

Module Data Point as required.

• Issue predefined or computed messages to the operator at the Universal Station to

inform the operator of current process conditions and to provide instructions. The
operator can also override various portions of the sequence, as required.

NOTE
With R530, the compile time of a loaded CL/APM sequence program is provided. Time and
Date stamp information is shown on the Detail Display of the UCN ProcMod point. To access
this page, select the target CONFIG PARAMS from the first page of the ProcMod Point Detail
Display.

APM Control Functions & Algorithms 6-3 12/03

 6.1.2

6.1.2 Sequence Program/Unit Partitioning

The user's process is usually partitioned into process units where the operators have the
responsibility to control one or more process units. To support this type of partitioning, the
APM Process Module Data Points (sequence programs) can be partitioned on a process unit
basis as shown in Figure 6-2. This is accomplished by using the following three elements:

• The set of CL/APM sequence programs that control individual process unit.

• The set of process monitoring and control elements that are used by the sequence
program to control the operation of the process unit.

• The operating displays at the Universal Station such as the Module Summary Display
(see Figure 6-3) which shows the current status of the process modules on a process unit
basis, and the Module Group and Module Detail displays which allow the operator to
start and stop the sequence programs, override various portions of the sequence
programs, etc.

APM Control Functions & Algorithms 6-4 12/03

 6.1.2

Wherever possible, process unit partitioning should be consistent with the inherent
boundaries in the system, such as:

• The beginning and end points of major separable segments of a process.

• The physical separations or classifications of process equipment components.

Advanced Process Manager Module

(APMM)

Process Module Data Points

1 2 3 4 5 • • • • (Sequence Slots)• • • • • • • • 160

Unit 1 Unit 2 Unit 3 Unit 4 Unit 5

Process Equipment

Figure 6-2 — Sequence Program Partitioning/Unit Partitioning 11013

APM Control Functions & Algorithms 6-5 12/03

 6.1.3

SEQUENCE-EXECUTION SEQUENCE-EXECUTION
MODULE STATE MODE PHASE NAME
OPERATING
STATUS

SEQUENCE NAME DDMMMYY 11:22:46 2

MODULE NAME MODULE SUMMARY PAGE 1

UNIT ID UNIT MODULE SEQUENCE OPER EXEC MODE PHASE STEP MSG BATCH 1D

SINGLE-PROCESS
01 EM1 REACT NORM RUN AUTO SETUP ST2 CFM
MODULE LINE 01 EM2 OFF NL AUTO

STEP LABEL

MESSAGE INDICATOR

BATCH NAME (if any)

Figure 6-3 — Module Summary Display 11014

6.1.3 Writing the Sequence Programs

Sequence programs are written in CL/APM and compiled at a Universal Station. At

compilation time, each sequence program is bound to a specific Process Module Data Point
(i.e., a specific sequence slot) and is written to a separate object file. These files can be
directly downline loaded through the NIM to the process module slots in the designated
APM.

• To prepare CL/APM programs, refer to the CL/APM Reference Manual in the

Implementation/Advanced Process Manager - 2 Binder.

• To compile a CL/APM program (binding it to a process module point) and load it into
the APM, refer to the CL/APM Data Entry publication in the Implementation/Advanced
Process Manager - 2 binder.

6.1.3.1 Sequence Library

The Sequence Library contains the names of the sequence programs. The Sequence
Library is divided into three sections, with each section having a maximum of 1000
entries. (The section is defined by the LIBRYNUM parameter.) A section of the library
can be viewed by reconstituting the point, using $NxxLiby where xx is the UCN number
on which the NIM resides and y is the section number of the library.

APM Control Functions & Algorithms 6-6 12/03

 6.1.3

The library entries can be made automatically by the CL Compiler, or they can be entered
manually by the user. If the manual entry method is to be used, the user should first enter
the names on the NIM Library Configuration Form, AP88-540. The LIBRYTXT parameter
defines the allowable character set for the library entries.

Library 1 is reserved for sequence names; Libraries 2 and 3 are reserved for all other names.
If the CL Compiler completely fills up Libraries 2 and 3, the compiler will begin entering
the overflow information into Library 1, beginning with index number 1,000 and working
down towards index number 2.

The sequence library resides in the NIM, and it is applicable to all the APMs (or PMs or
HPMs) on the same UCN.

6.1.3.2 Local Flags, Numerics, String and Time Variables

Each Process Module Data Point contains 127 local flags, 80 local numerics, 4 local time
variables, and 16 local 8-character strings. The strings can alternatively be allocated as 8
16-character, 4 32-character, or 2 64-character strings. Flags are designated FL(1) to
FL(127) and the numerics are designated NN(1) to NN(80). Times are designated TIME(1)
to TIME(4) and Strings are designated STRn(mm) where n is the string length (8, 16, 32,
64) and mm is the specific string number. For example, STR8(15) for 8-character strings,
STR16(7) for 16-character strings, etc.

The primary purpose of the flags and numerics is to provide storage for recipe data and
intermediate results. Time variables are used to record date/time information, and strings
contain text strings that name or describe things. These local variables can be accessed by
the sequence executing in the same process module in which they reside, or they can be
accessed by any other sequence in the same APM. The flags and numerics can also be
accessed by all system functions, such as CL programs in the AM, Universal Station
displays, etc. They can be accessed as local variables by CL/APM by using the AT clause.
Refer to the CL/APM Reference Manual.

These local variables are accessed by the various system elements using the
"Tagname.Parameter" convention where the Tagname is the name of the process module in
which they reside, and the "Parameter" is the parameter name such as FL(15), NN(25),
STR8(15), or Time(4). To store (write) into the local flags and numerics, the keylock
position must equal or exceed the minimum access level specified in parameter SPLOCK.

APM Control Functions & Algorithms 6-7 12/03

 6.1.4
Process module flags and numerics are set to the default values of OFF and NaN
respectively, when the process module data point is deleted or when the APM database is
initialized to default values. Time and string variables are initialized to spaces and 0
seconds, respectively. The APM database is set to default values on initial loading of the
APM Box data point and when the SCANRATE parameter or point mix changes in
subsequent loads of the APM Box data point. Process Module data point local flags and
numerics are left unchanged during downloading of sequence programs or the process
module data point itself to allow a record or history to exist between programs.

Flag, Numeric, String, Times, and Timer variables that reside in the APM box are a
different set of variables from the local flags, numerics, strings, and times. These variables
are available to the sequence programs in this APM and to the other sequence programs in
the APMs (or PMs or HPMs) on the same UCN and, with some minor restrictions, to other
system functions. They are described in Section 9 of this manual.

6.1.4 Sequence Program Structure

As shown in Figure 6-4, each sequence program consists of two main sections: the data
declaration section and the execution section.

The data declaration section requires the user to provide optional CL/APM statements that
relate user-defined names to APM flags, numerics, strings, and times that declare the
numeric constants, and that name the data points used in the program.

The execution section consists of one-to-three parts:

• A normal sequence that is the main program. The normal sequence is the main program
that provides control when conditions in the process are normal (e.g., the process is
proceeding within acceptable limits and does not require special control actions). The
main program is divided into "Phases," "Steps," and "Statements" as shown in Figure 6-4.

Phase—A sequence program consists of a grouping of phases. A phase executes a

major process function or marks a major process milestone, such as a charging phase
or heat-up phase. Phase boundaries are key points of synchronization in the control
program. A phase is identified in the sequence program by the PHASE statement, and
consists of optional steps and statements.

Step—A step executes a minor process function such as opening a valve with
associated checks and verification, or checking a temperature. At least one step is
executed each time the sequence is executed. A step is visible at a Universal Station
as a process milestone. It is identified in the sequence program by a STEP statement,
and consists of an ordered set of CL/APM statements. The step size is limited to a
maximum of 255 statements.

Statement—One CL/APM instruction. A statement performs an elementary action,

such as commanding a valve to open, do arithmetic operations, fetch variables, etc.

APM Control Functions & Algorithms 6-8 12/03

 6.1.4

Program Header

Data Declaration Section

Execution Section

Normal Sequence
Abnormal Condition
Handlers
Phase (Phasename)
Step (Stepname)
Statement Step (Stepname)
Statement Statement
• Statement
• •
• •
Statement Statement
Step (Stepname) •
•
END
Phase (Phasename)
Step (Stepname)
Statement
Statement Subroutines
•
• Step (Stepname)
Phase (Phasename) Statement
• •
• •
END END

Figure 6-4 — Sequence Program Structure 2549

• Subroutines—Subroutines simplify the program structure and are used for executing
repetitive functions, thereby reducing the programming effort and memory
requirements. Subroutines can be called by the normal sequence, other subroutines, or
abnormal condition handlers. Two levels of nesting are supported for both normal and
abnormal sequences. A runtime error is generated if the nesting level is violated.

Subroutines are specific to one sequence program, i.e., subroutines defined outside of
the program and maintained in subroutine libraries are not supported in the Advanced
Process Manager.

APM Control Functions & Algorithms 6-9 12/03

 6.1.4

• Abnormal-Condition Handlers—Abnormal-condition handlers provide corrective action

when abnormal conditions are encountered. The conditions can be detected when the
SEQEXEC value is Run, Pause, Fail, Error, or End. When such a condition is detected,
the normal sequence is suspended and the appropriate abnormal-condition handler
begins to execute. The types of abnormal-condition handlers are as follows:

– Hold—For a condition that requires a partial shutdown.

– Shutdown—For a condition that requires a systematic shutdown.

– Emergency Shutdown—For a condition that requires a complete, sudden shutdown.

Abnormal-condition handlers are identified in the sequence program by the HANDLER

statement, preceded by the name for the type of handler, and followed by the user-given
handler name, such as in the following example:

HOLD HANDLER cooldown

Abnormal-condition handlers consist of steps and statements. Hold and Shutdown

abnormal-condition handlers can be terminated by a restart section that is identified by
the RESTART statement, followed by the handler's END statement. An Emergency
Shutdown handler can be terminated by only the handler's END statement. Abnormal-
condition handlers have priority over each other and over the normal sequences. The
priorities are as follows:

Highest Priority – Emergency Shutdown

Shutdown
Hold
Lowest Priority – Normal Sequence

Note that the priority of a Restart Section is the same as the abnormal-condition handler
that contains the Restart Section.

The abnormal condition handlers can be enabled or disabled anywhere within a Phase
by using the ENB statement, which causes a suspend condition. The new conditions to
be monitored take effect immediately. The abnormal condition can also be enabled or
disabled by the phase header in the phase statement.

APM Control Functions & Algorithms 6-10 12/03

 6.1.5
6.1.5 Sequence Execution

6.1.5.1 Normal Execution

Execution of the normal sequence can be initiated by one of the following:

• Universal Station operator from the Process Module Detail Display.

• Another sequence, executing in another process module by using the INITIATE

statement. Generally, this other sequence is a master or supervisory sequence; that is, a
sequence program that initiates, monitors, and controls other sequences.

• CL Block in an AM which changes the PROCMOD parameter value in the APM to

Strt (Start).

• User-written program in a CM which changes the PROCMOD parameter value in the

APM to Strt (Start).

To manipulate the PROCMOD parameter successfully, the value of PROCMOD must be

Off, and the value of SEQEXEC must be Loaded. The keylock position must equal or
exceed the minimum access level specified in parameter CTLLOCK. The value of
PROCMOD can be changed to START from any keylock position regardless of the access
level specified in CTLLOCK.

6.1.5.2 Execution of Abnormal-Condition Handlers

Enabled abnormal-condition handlers can be initiated by one of the following:

• Request from a Universal Station operator.

• Predefined process condition detected by the sequence program at every pre-emption

point, such as before executing a step.

• Activation by a statement in the sequence (e.g., INITIATE HOLD).

• INITIATE statement from another sequence.

• CL block in an AM.

• User-written program in a CM.

6.1.6 Process Module Operating State

The process module operational state represents the operational condition of a process
module. The module state is represented through the PROCMOD parameter and the
allowable states are listed and described in Table 6-1. A state diagram is provided in
Figure 6-5.

APM Control Functions & Algorithms 6-11 12/03

 6.1.7

6.1.7 Sequence Execution Mode

The sequence execution mode defines the manner in which the sequence program is
executed. The sequence execution mode is established through the SEQMODE parameter,
and the allowable modes are listed and described in Table 6-2.

OFF

NORMAL

HOLD

EMERGENCY
SHUTDOWN
SHUTDOWN

Hold,
Shutdown,
Restart
Restart
Section
Section

2550

Figure 6-5 — Process Module Operating States 2550

APM Control Functions & Algorithms 6-12 12/03

 6.1.7

Table 6-1 — Process Module Operating States*

State Description

Off Process module slot is not being processed. A sequence program

can be assigned to a process module but it cannot be executed. The
sequence execution mode is not applicable to this module state.

Norm (Normal) The normal sequence program is running in the process module slot.

Hold Process module is executing the hold abnormal-condition handler.

Hold sequence may be initiated by one of the items listed in paragraph
6.1.5.2.

Shdn (Shutdown) Process module is executing the Shutdown abnormal-condition

handler. Shutdown sequence can be initiated by one of the items
listed in paragraph 6.1.5.2. Shutdown has priority over Hold.

Emsd (Emergency Process module is executing the Emergency Shutdown

Shutdown) abnormal-condition handler. Emergency Shutdown sequence
can be initiated by one of the items listed in paragraph 6.1.5.2.

* Parameter PROCMOD also contains the Strt (Start) and Stop states, which are transitional
states that can be controlled by one of the items listed in paragraph 6.1.5.2.

Table 6-2 — Sequence Execution Modes

Execution Mode Description

Auto (Automatic) Normal mode of operation. Sequence runs from beginning to end
without operator intervention.

SemiAuto Sequence stops at all PAUSE statements in the sequence.

(Semi-Automatic) Sequence can be restarted by the operator.

SnglStep Normally used for debugging. Sequence is executed one step at a

(Single-Step) time. Sequence can be restarted by the operator.

APM Control Functions & Algorithms 6-13 12/03

 6.1.8

6.1.8 Sequence Execution State

The sequence execution state represents the current state of the sequence program. These
states are defined through parameter SEQEXEC and are listed and described in Table 6-3.
Figure 6-6 shows the possible state transitions of the sequence.

NOT LOADED

LOADING

LOADED

RUN

END PAUSE FAIL ERROR

Figure 6-6 — Sequence Execution States 11022

APM Control Functions & Algorithms 6-14 12/03

 6.1.8

Table 6-3 — Sequence Execution States

Execution State Description

NL (Not Loaded) Initial state in which sequence has not been assigned to a process module.
This state is automatically entered from the DLL state when loading has
been aborted.

DLL (Down-Line Transient state during which the loading of the sequence into the process
Loading) module slot is in progress.

Loaded Sequence program has been loaded into the process module slot. This
state is automatically entered from the DLL state when loading has been
completed.

Run Sequence program is running.

Pause Execution of the sequence is suspended because of the execution of a

PAUSE statement, or the completion of a step when in the single-step
mode. Sequence execution can be resumed by the operator.

Fail Sequence execution is suspended because of the detection of one of

the failure conditions listed below. A system message that describes the
failure condition is generated. Sequence execution can be resumed by
the operator.

Failure
Code Definition

165 Sequence has been stopped by the operator.

166 Attempt to start an abnormal-condition handler that has not

been enabled and no lower-priority abnormal-condition-
handler is enabled. Possibly using INITIATE.
Suggestions: Use INITIATE with a When Error clause.

167 Not used.

168 Not used.

169 An attempt was made to start a sequence that was not loaded
into the process module slot.

170 Communication error detected in READ/WRITE statement.

Possible cause: a READ/WRITE statement without a When
Error Path fails a bad read. Note that a post store reports its
own failure code.
Suggestions:
• determine validity of the attempted fetch or store.
• check actual presence of point.

(Continued)

APM Control Functions & Algorithms 6-15 12/03

 6.1.8

Table 6-3 — Sequence Execution States (Continued)

Execution State Description

Fail (continued)

171 Communication error detected during an I/O Link access.

This error is generated for all post-store problems.
Possible cause:
• IO Link poststore failed.
• DI scan PV status is bad.
Suggestions:
• check I/O Link for reasons for bad post-store, or bad PV in
DI scan.

172 Range error has been detected.

Possible cause:
• box timer set point value greater than 32000.
• illegal stores to Digital Composite parameters.

173 Store failure because of "rights" error. For example, an

attempt was made to write to a parameter when the point was
not in the proper mode.
Possible cause:
• Other points reject stores.
• attempt to write to box timer set-point or time base when
state is in RUN.
• attempt to start timer when PV is greater than SP value.
• attempt to INITIATE a lower priority handler, while in a
higher priority handler.
Suggestion: check state of point not accepting the store.

174 An interlock error condition has been detected. (Not used).

175 –255 Reserved for future use.

Error Sequence execution is suspended because of the detection of one of

the error conditions listed below. A system message that describes the
error condition is generated. Sequence execution can be resumed by
the operator .

Error
Code Definition

101 Not used

102 Array index error

Possible cause: violated array index bound check.
Suggestions: check array bounds defined in the LOCAL
statement or in the subroutine header.

APM Control Functions & Algorithms 6-16 12/03

 6.1.8

Table 6-3 — Sequence Execution States (Continued)

Execution State Description

Error (Continued) Error

Code Definition
103 Illegal generated code
Possible cause:
• could not find variable operator code in the reference list
• invalid statement header
• unsupported built-in function call.
Suggestions: contact Honeywell Technical Assistance Center.
104 Illegal generated code referencing a parameter or variable.
Possible cause:
• bad box timer parameter code
• local numeric/flag index out of range
• invalid time base.
Suggestions: contact Honeywell Technical Assistance Center.
105 Interpreter stack overflow
Possible cause: Not enough stack depth.
Suggestions: contact Honeywell Technical Assistance Center.
106 GOTO destination error
Possible cause: Invalid destination.
Suggestions: contact Honeywell Technical Assistance Center.
107 Key-level error
Possible cause:
• tried store to read only parameter
• tried store with access level invalid
• system error
Suggestions: contact Honeywell Technical Assistance Center.
108 Configuration mismatch error
Possible cause:
• may be system error
Suggestions: contact Honeywell Technical Assistance Center.
109 I/O Link prefetch overflow
Possible cause: exceeded 12 I/O Link prefetches per step.
Suggestions: insert a new STEP in the code if several IOL
references are made within this step.
110 Subroutine nesting level error
Possible cause: nesting of subroutine calls is more than two
levels deep.
Suggestions: reduce nesting level of subroutine call to no
more than two. Note that a subroutine called from a normal or
abnormal program can call only one more level of subroutine.
111 Illegal value error
Possible cause: illegal value detected when doing
READ/WRITE or SET.
Suggestions: contact Honeywell Technical Assistance Center.

APM Control Functions & Algorithms 6-17 12/03

 6.1.8

Table 6-3 — Sequence Execution States (Continued)

Execution State Description

Error (Continued) Error

Code Definition
112 FAIL statement was executed by the sequence
Suggestions:
• restart.
• make necessary changes, then resume execution at the
next sequence statement.
113 I/O Link prefetch buffers full
Possible cause: IOL prefetch buffers full. Tried to fetch IOL
parameters eight times in a row, with preemption each time but
was unsuccessful.
Suggestions:
• redistribute I/O Link fetches to another programming cycle.
• Insert WAITS to slow collection down.
• break into additional STEPS.
114 I/O Link poststore buffers full.
Possible cause: I/O Link poststore buffers full. Tried to store
IOL parameters eight times in a row, with preemption each time
butwas unsuccessful.
Suggestions:
• redistribute I/O Link stores to another programming cycle
• Insert WAITS to slow collection down.
• break into additional STEPS.
115 UCN prefetch buffers full
Possible cause: I/O Link prefetch buffers full. Tried to fetch
UCN parameters sixteen times in a row, with preemption each
time but was unsuccessful.
Suggestions:
• redistribute reads to another programming cycle.
• Insert WAITS to slow collection down.
• break into additional STEPS.
116 UCN poststore buffers full.
Possible cause: I/O Link poststore buffers full. Tried to store.
UCN parameters sixteen times in a row, with preemption each.
time but was unsuccessful.
Suggestions:
• redistribute writes to another programming cycle.
• Insert WAITS to slow collection down.
• break into additional STEPS.
117 - 164 Reserved
End Sequence execution has been completed as indicated by the execution
of an END statement. This state is entered at the completion of a normal
sequence or an abnormal condition handler (Hold, Shutdown, or
Emergency Shutdown) sequence.

APM Control Functions & Algorithms 6-18 12/03

 6.1.9

6.1.9 Sequence Overrides

The process module displays at the Universal Station allow the user to perform phase, step,
and statement overrides when the sequence execution state is Fail, Error, or Pause. An
attempt to access the override function from anywhere other than the Universal Station
results in an error code of 107 (key-level error). The overrides are not restricted by the
value in CNTLOCK if the sequence execution state is Fail or Error.

• Phase Override—Allows the user to skip execution of one phase after another, in
forward or reverse order. Phase override works only in the sequence for which it is
invoked; it is implemented through the OVERPHAS parameter.

• Step Override—Allows the user to skip execution of one step after another, in forward
or reverse order. Step override works only in the phase for which it is invoked; it is
implemented through the OVERSTEP parameter.

• Statement Override—Allows user at a Universal Station to skip execution of one

statement after another, in forward or reverse order. Statement override works only in
the step for which it is invoked; it is implemented through the OVERSTAT parameter.

6.1.10 Sequence Alarms

Sequence alarms are generated when

• The process-module operational state is changed to Hold (HOLD), Shutdown (SHDN),

or Emergency Shutdown (EMSD) as indicated by a change in the PROCMOD
parameter. The PROCMOD parameter can be changed by entry into an abnormal
condition handler or externally by operator, AM, etc. The PROCMOD parameter has a
key level of Operator and can be written to from the LCN (by an operator, a CL/AM
program, etc.), or by a CL/APM program.

• The sequence execution state is changed to Fail, Error, or End as indicated by a change
in the SEQEXEC parameter. The SEQEXEC parameter has a key level of View only
and cannot be changed from the LCN or by a CL/APM program.

• The phase timer has elapsed as determined by the PHASETIM parameter.

6.1.10.1 Sequence Alarm Priorities

The priority of the sequence alarm can be configured for each process module through the
SEQPR parameter. The entry for this parameter can be Emergency, High, Low, JnlPrint,
Printer, Journal, or NoAction.

APM Control Functions & Algorithms 6-19 12/03

 6.1.11

6.1.11 Sequence Messages

6.1.11. 1 Sequence Status Messages

Sequence-status messages are issued when the:

• Process-module operational state is changed

• Sequence-execution mode is changed

• Sequence-execution state is changed

• Sequence begins a new phase.

• A sequence message is issued.

6.1.11.2 Operator Messages

Two types of programmed operator messages can be generated by the sequence program as
listed below.

• Message with feedback—A SEND statement with the confirmation option (WAIT)
causes the sequence to be suspended until the message has been confirmed by the user
at the Universal Station.

• Message without feedback—This message is a 1-way communication from the

sequence to a destination, such as the Universal Station.

These messages can be displayed at the Universal Station and/or logged on the printer,
depending on how the user codes the message statement.

It is good practice to confirm any outstanding messages after a sequence failure before
rerunning the sequence and before loading a new sequence.

APM Control Functions & Algorithms 6-20 12/03

 6.1.12

6.1.12 Restart Option

The restart option determines how the sequence program is started following a warm restart.
A Warm restart is considered as being a transition from Idle to Run, or a short power
interruption that does not change the APM database. The following restart options are
available:

• Restart—When the sequence-execution state is Run, the sequence program is started

from the very beginning; otherwise, the process module operational state is changed to
Off and the sequence-execution state is changed to Loaded (or Not Loaded if a sequence
has not been loaded). If an abnormal handler is executing when the warm start occurs,
execution begins from the beginning of the normal sequence and not from the abnormal
handler. A sequence-state change event is issued to report the transition from Hold,
Shutdown, or Emergency Shutdown to Normal.

• Off—The process module operational state is changed to Off and the sequence-
execution state is changed to Loaded (or Not Loaded if a sequence has not been loaded).

APM Control Functions & Algorithms 6-21 12/03

APM Control Functions & Algorithms 6-22 12/03
 7

REGULATORY PV POINT
Section 7

This section describes the functions available in the Regulatory PV (RegPV) point. The functions are
described first and are followed by detailed descriptions of the algorithms. Definitions of the
parameters mentioned in this section can be found in the Advanced Process Manager Parameter
Reference Dictionary.

7.1 FEATURES

While standard I/O functions such as engineering unit conversion and alarming are handled
directly by the I/O Processors, Regulatory PV (RegPV) points provide an easy-to-use
configurable approach for implementing PV calculations and compensation functions. PV
processing provides a menu of selectable algorithms such as mass flow, totalization, and
variable dead-time compensation.

The RegPV data point supports the following PV algorithms:

Data Acquisition (DataAcq)

Flow Compensation (FlowComp)

Middle of 3 Selector (Mid0f3)

High Low Average Selector (HiLoAvg)

Summer (Summer)

Variable Dead Time with Lead Lag (VDTLDLag)

Totalizer (Totalizr)

General Linearization (GenLin)

Calculator (Calcultr)

Detailed descriptions of these algorithms can be found in this section beginning with
paragraph 7.7.

Figure 7-1 is a functional diagram of the RegPV point.

APM Control Functions & Algorithms 7-1 12/03

 7.1

PV (from data point

specified by
input connection)

PV INPUT
NOPINPTS PROCESSING

PVALGID PV USER-SUPPLIED
ALGORITHM :
: VALUES FOR THE
CALCULATION CONFIGURED
PVINIT
ALGORITHM
PVCALC
(in EU)

PVCLAMP Noclamp
PVEXEUHI PV FILTERING Clamp
PVEXEULO AND
TF RANGE CHECK PVEXHIFL
PVEXLOFL

PVAUTO

PNTFORM
Componnt
PVMan or PVSub Full
(from Operator or Program)
PVAUTO
PV
PVSOURCE

Man/Sub Auto Auto

PVEUHI PVP (PV in %)
Man/Sub NORMALIZATION
PVEULO LASTPV

PVEXEUHI RANGE PVEXHIFL

CHECKING
PVEXEULO PVEXLOFL

PV

Half
A HIGHAL
One
L
Two A
PVALDB R
Three
M
Four
Five
D
PVHHTP E
PVHHFL
T
PVHHPR E PVHIFL
: C :
PV ALARM : T : PV ALARM
TRIP POINTS : I : FLAGS
AND PRIORITIES : O :
PVROCPTP N PVROCNFL
PVROCPPR PVROCPFL

PTINAL

Fig. 7-1
UC09-200
#2080

Figure 7-1 — Regulatory PV Point, Functional Diagram 2080

APM Control Functions & Algorithms 7-2 12/03

 7.2
7.2 PV INPUT CONNECTIONS
PV input connections are used to specify the source(s) for the inputs to PV algorithms. A
maximum of six PV input connections can be configured for an algorithm, as required by the
individual PV algorithm. The user can implement the input connections by using the
"Tagname.Parameter" format.
When using the "Tagname.Parameter" format, the user must enter the tag name of the data
point and the name of the parameter within that data point. The source parameter must
contain a real number, integer, or Boolean quantity. The values provided by the input
connection parameters are assigned to destination parameters within the RegPV point by
the PIDSTN parameter. The destination parameters for these sources default to one for each
input to the configured PV algorithm.
One input connection must be configured for each algorithm input, otherwise the point
cannot be made active.
7.3 PV ALGORITHM CALCULATION
The configured PV algorithm accepts the values received through the PV input connections
and produces the calculated PV value (PVCALC) plus its value status (PVAUTOST). The
PV algorithms are described beginning with paragraph 7.7.
7.4 PV RANGE CHECK AND FILTERING
The PV range is configured in PVEULO and PVEUHI in a range from 0% to 100.0% of the
engineering-units range. This is usually the normal operating range for the PV but it can
extend into a configurable extended range, as defined by PVEXEULO and PVEXEUHI.
The extended range is forced to be equal to or greater than the range defined by PVEULO
and PVEUHI. PVCALC is generally constrained within PVEXEULO and PVEXEUHI, but
the checks and constraints depend on the PV source, as follows:
• If PVSOURCE is Auto—(1) If PVAUTOST contains Bad, PVSTS is Bad and no PV-
range checks are made. (2) If PVAUTO is outside the extended range and PV clamping
(PVCLAMP) is not configured, the PV becomes a bad value and PVSTS is Bad; however,
if PV clamping is configured, the PV becomes equal to the value of the violated range and
PVSTS becomes Uncertn. In either case, the appropriate PV-range violation flag is set
(PVEXLOFL or PVEXHIFL).
• If PVSOURCE is Man—Any value from the Universal Station that is outside the extended
range is not accepted. PVSTS is already uncertain because the source is Man.
• If PVSOURCE contains Sub—If a program stores a PV value outside the extended range, the
appropriate PVEXLOFL or PVEXHIFL flag is set. PVSTS is already uncertain because
the source is Sub.
If clamping of the output is specified by the PVCLAMP parameter, PV filtering is performed
before the range check. If the value entered for PV filtering through the TF parameter is other
than the default value of 0.0, a single-lag filter is applied to the PVCALC value to remove noise.
If a filter value is not specified, PVAUTO contains the same value as PVCALC.
Data-point parameter LASTPV always holds the last good value of the PV.

APM Control Functions & Algorithms 7-3 12/03

 7.4.1
7.4.1 PV Value Status
The value in the PV value-status parameter, PVSTS, is determined as follows:
Normal PVSOURCE = Auto, PVAUTOST = Normal, and the PV value is within the
range defined by PVEULO and PVEUHI.
Uncertn 1) PVSOURCE = Man or Sub and the PV value does not equal NaN (i.e., is a
valid, real number), or,
2) PVSOURCE = Auto, and PVAUTOST = Uncertn. Note that PVAUTOST
contains Uncertn if at least one of the required algorithm inputs is Uncertn
and none of the required algorithm inputs is Bad, or,
3) PVSOURCE = Auto and the value in PVAUTO is outside the engineering-
units range and is clamped.
Bad The PV value is NaN. This results from one of the following;
1) PVSOURCE = Auto and PVAUTO = NaN.
2) PVSOURCE = Auto, the value in PVAUTO is out-of-range, and has not
been clamped.
3) PVSOURCE = Sub or Man and the PV is stored as NaN.
7.5 PV SOURCE SELECTION
The source of the PV can be PV processing, a Universal Station, or a user-written program,
as shown in Figure 7-1. It is specified by the PVSOURCE parameter, whose value can be
changed by an operator, a supervisor, an engineer, or a user-written program. The
PVSOURCE parameter is configurable only if Full has been entered for the PNTFORM
parameter. PVSOURCE can have one of the values:
• Auto—PV is received from PV processing through the PV filtering function. The value is
in PVAUTO and its status is contained in PVAUTOST. During normal operation, the PV
source is Auto, and the PV and its value status (PVSTS) become equal to PVAUTO and
PVAUTOST, respectively, before PV range checks are made. When the PV source is
changed from Auto to Man or Sub, the PV remains at the last value until it is changed by
the operator (Man) or a program (Sub), so it doesn't "bump." In Man or Sub, the status in
PVSTS is Uncertn. When the PV source is changed from Man or Sub to Auto, the PV
immediately goes to the PVAUTO value. This might cause a bump in the value unless it
is changed gradually to the value in PVAUTO before changing the source.
• Man—The PV is entered by an operator, supervisor, or engineer at a Universal Station.
• Sub—The PV is entered by a user-written program. A program can store a bad value in
PV, and if it does, PVSTS goes Bad.
You can prevent PV source changes by configuring OnlyAuto in PVSRCOPT. This fixes
the source as Auto and the parameter PVSOURCE is removed from the point. Configuring
All in PVSRCOPT allows normal PV source selection.

APM Control Functions & Algorithms 7-4 12/03

 7.6

7.6 PV ALARM DETECTION

The PV alarming function can be implemented only when Full has been entered for the
PNTFORM parameter. The following types of alarms are detected during PV alarm
processing:

PV High/Low
PV High-High/Low-Low
PV Rate-of-Change Positive/Negative
PV Significant Change
BadPV

PV source selection has no effect on alarm processing. For more detailed alarm
information, refer to paragraph 4.3 in System Control Functions.

7.7 PV ALGORITHMS

The PV Algorithms in the APM are described in the sections that follow. Each of the PV
algorithm descriptions has the same form and the same headings:

TYPE AND NAME

FUNCTION

USE

OPTIONS, EQUATIONS, AND SPECIAL FEATURES

Each of the algorithm descriptions mentions several parameters associated with the
algorithm. The parameter names consist of CAPITAL letters. References to parameters not
named in the descriptions are provided after the descriptions. Further information on all
data-point parameters, including the data type, range, and access keys, is provided in the
Advanced Process Manager Parameter Reference Dictionary.

APM Control Functions & Algorithms 7-5 12/03

 7.7.1

7.7.1 Data Acquisition (DATAACQ)

7.7.1.1 Function

This algorithm normally accepts the input and places it, unchanged, in PVCALC. All of the
other PV algorithms alter the input(s) in some way. See Figure 7-2.

7.7.1.2 Use

The most common use of this algorithm is to provide a PV that has been through PV Input
Processing, PV Algorithm Processing, PV Filtering, and PV Source Selection (see Figure
7-1). The value in PVCALC is filtered, and becomes PV, if the PV source is Auto.

The input can be a measured process-variable, or the calculated PV or calculated output of

another data point.

The input to this algorithm and its output are in engineering units.

7.7.1.3 Options and Special Features

This algorithm has neither options nor special features.

7.7.1.4 Equation

This algorithm has one equation form. The operation is simply the replacement of the data
point's calculated PV (PVCALC) with the value of the input:
PVCALC = P1

Where P1 contains the first input value and PVCALC contains the value that becomes the
PV when PVSOURCE = Auto.

The parameters associated with with this algorithm are P1, PVCALC, and P1STS. Refer to
the Advanced Process Manager Parameter Reference Dictionary.

Measured
Process Value
or Calculated (Data Point
P1 PVCALC
Value from Parameter)
Another Data
Point

Figure 7-2 — Functional Diagram, Data Acquisition PV Algorithm 1304

APM Control Functions & Algorithms 7-6 12/03

 7.7.2

7.7.2 Flow Compensation (FLOWCOMP)

7.7.2.1 Function

This algorithm compensates a flow measurement for variations in temperature, absolute

pressure, specific gravity, or molecular weight. The measured flow can be that of a gas, a
vapor, or a liquid. An extended equation is provided for industrial steam-flow
compensation, which includes factors that compensate for steam quality and
compressibility. See Figure 7-3.

7.7.2.2 Use

The uncompensated-flow input is typically a square-rooted, differential pressure

measurement. Other direct-flow measurements can also be used. The square root should be
extracted before the input to the data point, and the input value must be in engineering
units. For process-connected inputs, the square root can be extracted in the IOP; conversion
to EUs also takes place in the IOP.

The compensation is calculated from temperature, pressure, specific gravity, molecular

weight, steam quality, or steam compressibility. Choice of inputs depends on the type of the
equation selected. All of these inputs are obtained through PV input-connections.

Flow Input F
P
COMPTERM G FLOWCOMP (Data Point
PVCALC
Inputs T Parameter)
Q
Z

Simplified Equation:

PVCALC = F*COMPTERM

Where F is uncompensated flow and

COMPTERM has five forms:

A: Liquids
B: Gases, Vapors
C: Gases, Vapors (Spec. Gravity)
D: Volumetric Flow of Gases and Vapors
E: Steam

Figure 7-3 — Functional Diagram, Flow Compensation PV Algorithm 1305

APM Control Functions & Algorithms 7-7 12/03

 7.7.2
7.7.2.3 Options and Special Features

Five Forms of Flow Compensation

Parameter PVEQN specifies one of five different equations for this algorithm. The equation
causes the compensation term (COMPTERM) to differ according to the application, as
follows (see 7.7.2.4 for the actual equations):

Equation A

Primarily used for mass-flow or volumetric-flow compensation for liquids. Actual

(measured or calculated) specific gravity is used as a compensation input.

Equation B

Primarily used for mass-flow compensation of gas or vapor flows. Actual absolute
temperature and pressure are used as compensation inputs.

Equation C

Used for mass-flow compensation of gas or vapor flows. Actual specific gravity
(measured or calculated), absolute temperature, and pressure are used as compensation
inputs.

Equation D

Principally used for volumetric-flow compensation for gas or vapor flows. Actual
temperature, pressure, and molecular weight are used as compensation inputs. The
molecular weight can be calculated by the Calculator algorithm, or a user written program
in the AM or Computing Module (CM50/CM60).

Equation E

Used for mass-flow compensation of steam flows in industrial applications. Actual temperature,
pressure, specific gravity, steam compressibility, and steam quality are used as compensation
inputs. This equation can also be used for "custody transfer" of gases or liquids.

Restart or Point Activation

On a cold or warm restart, or when this data point is activated, PVCALC is recalculated the
next time the FLOWCOMP data point is processed.

Error Handling

If the status of any of the input values is bad, PVCALC contains NaN and the PVAUTOST
becomes Bad. If there are no bad inputs but the status of one or more of the inputs is
"uncertain," the PVAUTOST becomes Uncertn.

APM Control Functions & Algorithms 7-8 12/03

 7.7.2
Special Notes

Refer to 7.7.2.4, Equations, for more detail on the inputs and parameters mentioned in
these notes.

Zero Pressure Reference—Parameter P0 (see definition of this parameter under 7.7.2.4)

compensates for ambient atmospheric pressure. Most pressure sensors measure pressure
relative to the atmospheric pressure. If the pressure measurement is actually absolute, P0
must be set to a value of zero. The usual zero reference is a value for sea level. If the
pressure sensor is at a significantly different elevation than sea level, P0 should be set to a
more appropriate value. For example, Denver, Colorado has an average atmospheric
pressure of about 12.2 psia. Standard sea-level atmospheric pressure is 14.696 psia. P0
contains the absolute value of ambient atmospheric pressure.

Units of Measure—The absolute value of either U.S. Customary Units or SI (metric) units
can be used. All inputs and parameters must be in engineering units of one system or the
other. The typical value for P0 (see definition of this parameter under 7.7.2.4) in U.S.
Customary Units is 14.696 psia and in SI units it is 101.325 kPa. The typical T0 value is
459.69°F in U.S. Customary Units and 273.15°C in SI units.

Compensation Term Value—Typically, the COMPTERM value is near 1. It should never

be zero or negative. The COMPLO and COMPHI limits are used to prevent unrealistic
values of COMPTERM caused by incorrect inputs. Should the calculated value of
COMPTERM go beyond one of these limits, the value is held (clamped) at that limit. You
should estimate the range of COMPTERM by considering the most extreme input-
conditions you expect. Also, you should set the PV range for this data point, by considering
the largest compensated-flow value expected.

Custody Transfer—Equation E can be used for "custody transfer" of gases or liquids. To

do so, set parameter RX (see definition of this parameter under 7.7.2.4) equal to one and
specify the input connection to X to come from RX in this data point.

Compensating for Assumed Design Conditions

Equation A can be used for either mass or volumetric compensation of liquid flows. The
use depends on whether the measurement of uncompensated flow is a mass measurement or
a volumetric measurement, and on the desired uncompensated-flow units. Here are three
ways to use Equation A:

• Converting an uncompensated mass-flow to compensated mass-flow; C1 and C2

(see 7.7.2.4) are configured as 1.0.
• Converting an uncompensated, standard volumetric-flow to compensated mass-
flow; C1 is configured to equal the design density, referenced to standard conditions. C2
is configured as 1.0.

APM Control Functions & Algorithms 7-9 12/03

 7.7.2

• Converting uncompensated, standard volumetric-flow to compensated, standard

volumetric-flow; If the variations in standard density caused by fluid-composition
changes are significant, C2 is manipulated as follows:

If the measured value of specific gravity at flow conditions is available, the actual
specific gravity, referred to standard conditions, is calculated from that measurement
by another data point and input to C2 through a general input connection. If actual
specific gravity is measured by a lab, a numeric data-point could be used to hold the
value and input to C1 through a general input connection. For the latter case, another
data point uses the lab value to calculate specific gravity at flow conditions and the
result is input G.

7.7.2.4 Equations

You configure PVEQN for data point that uses the Flow Compensation algorithm to specify
one of five equations. The equations select the compensation term. The basic equation is

C1
PVCALC = C * C2 * F * COMPTERM

Where:

PVCALC = The output of this algorithm. It is selected as the PV for this

data point when the PVSOURCE is Auto.

C = Scale factor. The default value is 1.0.

C1, C2 = Constants for correcting for assumed design conditions. See

Compensating for Assumed Designed Conditions under
7.7.2.3. Default value for each is 1.0.

F = The uncompensated flow input. A square-rooted, differential

pressure input.

COMPTERM = The compensation term. This term differs in each of the five
flow-compensation equations, A through E. Its value lies
between the COMPLO and COMPHI limits, which are
specified by the process engineer. If either limit parameter
contains NaN, the corresponding limit check is not made.

APM Control Functions & Algorithms 7-10 12/03

 7.7.2
The five forms of COMPTERM are as follows:

NOTE
The equations shown below are performed using absolute values for pressure and temperature.
You must convert temperatures and pressures to absolute values in order to use this algorithm.

The COMPTERM computation depends on the value of the PVCHAR parameter. If

PVCHAR = SqrRoot, then COMPTERM is as shown. If PVCHAR = Linear, then
COMPTERM is determined without the square root function.

G
Equation A: COMPTERM = RG (Liquids)

P+P0 RT
Equation B: COMPTERM = RP * T+T0 (Gases & Vapors)

P+P0 RT G
Equation C: COMPTERM = RP * T+T0 * RG (Gases & Vapors
w/Specific Gravity)

P+P0 RT RG
Equation D: COMPTERM = RP * T+T0 * G (Volumetric Flow
of Gases & Vapors)

P+P0 RT X RQ
Equation E: COMPTERM = RP * T+T0 * RX * Q (Steam)

Where the following (in engineering units) are received through input connections
G = Measured or calculated specific gravity or molecular weight.
P = Measured actual gage pressure.
T = Measured actual temperature.
X = Measured actual steam compressibility.
Q = Measured actual steam-quality factor.
And the following parameters are specified by the process engineer
RG = Design specific gravity or reference molecular weight, in the same
engineering units as G (Default value = 1.0).
RP = Design pressure, converted to an absolute value (Default value = 1.0).

APM Control Functions & Algorithms 7-11 12/03

 7.7.2

RQ = Design steam quality factor, in the same units as Q (Default value =1.0)

RT = Design temperature, converted to an absolute value (Default value = 1.0).

P0 = Factor to convert gauge pressure to an absolute value. Typically 14.696

psia or 101.325 kPa. Enter the absolute value of the number. See 7.7.2.3
- Special Notes. Default value = 0. If the measured pressure is already an
absolute value, enter 0.

T0 = Factor to convert Celsius and Fahrenheit temperatures to an absolute

value. Typically 459.69°F or 273.15°C (use the absolute value of the
number when entering a value in T0). See Special Notes. Default value
= 0. If the measured temperature is already an absolute value, enter 0.

RX = Reference steam compressibility, in the same engineering units as X.

Default value = 1.0.

Other parameters associated with this algorithm are as follows (refer to the Advanced
Process Manager Parameter Reference Dictionary):
COMPHILM
COMPLOLM
COMPTERM
FSTS
GSTS
PSTS
PVCALC
PVEQN
QSTS
TSTS
XSTS

APM Control Functions & Algorithms 7-12 12/03

 7.7.3
7.7.3 Middle of Three Selector (MIDOF3)
7.7.3.1 Function

This algorithm provides a calculated PV (PVCALC) that is normally the middle value of
three values from the PV input connections. PVAUTOST is Bad, only if all three inputs to
this algorithm are bad. If at least one input is valid (normal or uncertain), the algorithm
provides a valid value in PVCALC.
When configured with only two inputs, this algorithm serves as a high/low selector or input
averaging block. These functions are selected by choosing the corresponding control
equation (A, B or C as shown below).
If only one valid input value is available, it is selected. If only two valid input values are
available, the selected value can be the highest or the lowest, or the average of the two, as
specified when you select the equation to be used by this algorithm. See Figure 7-4.

P1
PVCALC
P2 MIDOF3 (Data Point
Parameter)
SELINP
P3

Normal Operation: PVCALC = Middle value of the three input values.

With only two valid inputs:

Equation A; PVCALC = Highest of the two inputs

Equation B; PVCALC = Lowest of the two inputs

Equation C; PVCALC = Average of the two inputs

With only one valid input: PVCALC = Value of the input

SELINP = The selected input, SelectP1 through SelectP3, except,

with only two valid inputs and Eq. C, SELINP contains None.

Figure 7-4 — Functional Diagram, Middle-of-Three Selector PV Algorithm 1312

7.7.3.2 Use

This algorithm is used to provide a reasonably secure PVCALC when inputs are available
from three redundant inputs, one or more of which may occasionally fail or provide erratic
values. The Low Selector, High Selector, Average PV algorithm provides a somewhat
similar function with up-to-six input connections (see 7.7.4).

APM Control Functions & Algorithms 7-13 12/03

 7.7.3
7.7.3.3 Options and Features

Normal Operation with Three Valid Inputs

Normal operation occurs if there are no inputs with a bad-value status. Inputs are treated as
valid if their value status is either normal or uncertain.

If no two inputs have equal values,

PVCALC = the middle value of the three inputs, P1, P2 and P3

and
SELINP = the selected input, SelectP1 through SelectP3

If there are two inputs with equal values or if all three input values are equal,

PVCALC = the value for which there is at least one other equal
and
SELINP = the lowest-number input with and equal value, SelectP1
through SelectP3.

Error Handling

PVAUTOST becomes Uncertn only when the selected input is uncertain, or for equation C,
when one of the inputs used for averaging is uncertain.

The PVAUTO status is bad and PVCALC becomes NaN when the status of all three inputs
is bad.

7.7.3.4 Equations

If three valid inputs are present, the equations have no meaning and the algorithm functions
normally, as described under Normal Operation with Three Valid Inputs. The equations
specify what the algorithm is to do if one or more inputs has a bad-value status. The
equations function as follows:

• With one bad input

Equation A

PVCALC = Highest of the two input values

SELINP = The selected input, SelectP1 through SelectP3
Equation B

PVCALC = Lowest of the two input values

SELINP = The selected input, SelectP1 through SelectP3

APM Control Functions & Algorithms 7-14 12/03

 7.7.3
Equation C

PVCALC = The average of the two input values

SELINP = None

• With two bad inputs

Equations A, B and C

PVCALC = the value of the valid input

SELINP = The selected input, SelectP1 through SelectP3

• With three bad inputs

Equations A, B, and C

PVCALC = NaN
SELINP = None

Where:
PVCALC = The output of this algorithm. It is selected as the PV for the data
point when the PVSOURCE is Auto.
P1, P2, and P3 The input values. The default value is NaN.

SELINP = The selected input, SelectP1 through SelectP3. If no input is

selected or if PVCALC contains an average value, SELINP
contains None.

Other parameters associated with the MIDOF3 algorithm are as follows

P1STS P3STS P2STS PVEQN

Refer to the Advanced Process Manager Parameter Reference Dictionary for more
information.

APM Control Functions & Algorithms 7-15 12/03

 7.7.4
7.7.4 High Selector, Low Selector, Average (HILOAVG)
7.7.4.1 Function

This algorithm does one of the following:

• Selects the input with the highest value

• Selects the input with the lowest value

• Calculates the average value of all valid inputs

It can accept up to six inputs. Valid inputs are those with a status that is "Normal" or
"Uncertain." When the input selection functions are used, the number of the input that is
selected is contained in a accessible parameter (SELINP). See Figure 7-5.

7.7.4.2 Use

One example of the use of this algorithm is shown at the top of Figure 7-5. In this example,
the high value-selector version of the algorithm is used to detect hot spots in a boiler or a
reactor.

Either the high value-selector version or the low value-selector version can be used to
detect production bottlenecks. For example, this algorithm might be used to notify the
process operator that production is currently constrained by the speed of a gas compressor.
One of the selector options might also be used to select the "safest" PV for control.

One use of the averaging option is in balancing furnace passes. In this application, the
algorithm calculates the average of the outlet temperatures of the passes.

7.7.4.3 Options and Special Features

Forced Selection

The data point can be configured to allow the Universal Station operator, a user-written
program, or a general-input connection to force selection of one of the inputs.

• If the FRCPERM parameter is configured as On, the forced-selection function is

enabled and an operator or a user-written program can force the selection.

• IF FRCPERM is configured as Off, the forced-selection function is disabled.

The FSELIN parameter specifies the input to be selected, when selection is forced (SelectP1
through SelectP6).

APM Control Functions & Algorithms 7-16 12/03

 7.7.4

Typically a flow P1
measurement Time-scaled
TOTALIZR PVCALC accumulation
Start
Stop
Operator or user-
Reset Target value
written program TIMEBASE flags
Target Value

Equations A through F specify bad value and

restart-handling options. See 7.4.5
For all equations:
PVCALC = PVCALC(i-1) + C * (Time Scale)* P1

Figure 7-5 — Functional Diagram, HI LO Average Selector PV Algorithm 1310

APM Control Functions & Algorithms 7-17 12/03

 7.7.4

Error Handling

Except when forced selection is in effect (Forced Selection), inputs with a bad status are
ignored and they do not make the PVAUTOST is Bad. For example, if the algorithm is
configured as a 4-input high-selector and one of the inputs goes bad, the algorithm
functions as a 3-input high-selector.

If the number of valid inputs (PVSTS is Normal or Uncertn) is less than the minimum
number specified in parameter NMIN, PVCALC becomes NaN and the PVAUTOST is
Bad.

PVAUTOST is changed to Uncertn under any of the following conditions:

• An input selection is forced and the status of that input is not bad (is normal or
uncertain).

• Forced selection is not in effect, at least as many inputs as specified by NMIN are
normal or uncertain, and the status of the selected one (Equation A or B) is uncertain.

• Equation C (averaging) is chosen, at least as many inputs as specified by NMIN are not
bad (normal or uncertain), and the status of any of them is uncertain.

PVCALC becomes NaN and PVAUTOST becomes Bad under either of the following
conditions:

• The selection of an input is forced and the status of that input is bad.

• Forced selection is not in effect, and there are fewer inputs with a status other than bad
than are specified by NMIN.

Restart or Point Activation

On a cold or warm restart, or when this data point is activated, PVCALC is simply
recalculated the next time this data point is processed.

APM Control Functions & Algorithms 7-18 12/03

 7.7.4

7.7.4.4 Equations

Equation A selects the highest input value. Equation B selects the lowest input value.
Equation C calculates the average of all valid inputs.

Equation A—High Selector

If FRCPERM and FORCE are both On,

PVCALC = the value of the input indicated by FSELIN and

SELINP = FSELIN

If either FRCPERM or FORCE is Off,

PVCALC = the highest valid input.

SELINP = the selected input, SelectP1 through SelectP8.

Equation B—Low Selector

If FRCPERM and FORCE are both On,

PVCALC = the value of the input indicated by FSELIN and

SELINP = FSELIN

If either FRCPERM or FORCE is Off,

PVCALC = the lowest valid input.

SELINP = the selected input, SelectP1 through SelectP8.

Equation C—Average

If FRCPERM and FORCE are both On,

PVCALC = the value of the input indicated by FSELIN and

SELINP = FSELIN

If either FRCPERM or FORCE is Off,

PVCALC = (Sum of the valid inputs)/N

SELINP = None
Other parameters associated with the HILOAVG algorithm are as follows (refer to the
Advanced Process Manager Parameter Reference Dictionary):
NMIN PVEQN PnSTS SELINP

APM Control Functions & Algorithms 7-19 12/03

 7.7.5

7.7.5 Summer (SUMMER)

7.7.5.1 Function

This algorithm calculates a PV (PVCALC) that is the sum of up-to-six input values. The
input values can be scaled, the combined inputs can be scaled, and a bias value can be
added to the result. See Figure 7-6.

P1
P2
P3 (Data Point
P4 SUMMER PVCALC
Parameters)
P5
P6

EQUATION B, simplified:

PVCALC = P1 + P2 + . . . + P6

Figure 7-6 — Functional Diagram, Summer PV Algorithm 1314

7.7.5.2 Use

A typical use is the calculation of the rate at which a component of a raw product is entering
a process unit, which is found by summing the proportion of the component in each of
several input streams and multiplying by the stream flow rates. This algorithm can also be
used to calculate a net heat loss by finding the difference between the heat inputs and heat
outputs (the difference can be obtained by using a negative scale factor, for example, –1.0).
Other possible uses are mass-balance, heat-balance, and inventory calculations.
This equation can be used to scale and bias a single variable; see 7.7.5.4 Equation A.

APM Control Functions & Algorithms 7-20 12/03

 7.7.5
7.7.5.3 Options and Special Features

Ensuring Adequate PV Range

Because the input values can be either positive or negative, as can the scale factors and bias
values, the results in PVCALC can have a broad range of values. You should evaluate the
worst-case values you expect to be in use, to establish the PV range. When you configure
the data point, be sure to specify a PV range adequate to cover all expected values.
Error Handling

If there are no inputs with a bad status and the status of at least one input is uncertain,
PVAUTOST is Uncertn.
If the status of at least one input is bad, the PVAUTOST becomes Bad and PVCALC
contains NaN.
Restart or Point Activation

On any type of restart or when this data point is activated, PVCALC is normally calculated.

7.7.5.4 Equations

You can select one of two equations when you configure a data point that uses the Summer
PV algorithm:
Equation A

PVCALC = C * P1 + D

Equation B

PVCALC = C * ((C1 * P1) + (C2 * P2) + . . . + (Cn * Pn)) + D

(Pn <= 6)

Where:
PVCALC = The output of this algorithm. It is selected as the PV for this
data point when the PV source is AUTOmatic.
C = The overall scale factor. Default = 1.0.
C1 through Cn = The scale factors for P1 through Pn. Default = 1.0.
P1 through Pn = The PV input values. Equation B is limited to six inputs.
Default for all values is NaN.
D = The overall bias. Default = 0.
n = The number of PV inputs used. Default = 2.
Other parameters associated with the SUMMER algorithm are: N, PnSTS and PVEQN.
Refer to the Advanced Process Manager Parameter Reference Dictionary for more information.

APM Control Functions & Algorithms 7-21 12/03

 7.7.6
7.7.6 Variable Dead Time with Lead-Lag Compensation (VDTLDLG)
7.7.6.1 Function

This algorithm provides a calculated PV (PVCALC) in which value changes may be

delayed from the time that the corresponding change occurred in the P1 input. Dynamic
lead-lag compensation to the PV can also be provided. Lag compensation is available in
combination with the delay or with no delay. The delay time can be fixed or can be varied
as the value of an input varies. See Figure 7-7.

Process Input P1

(Data Point
PVCALC
Parameter)

Variable Dead
P2
Time Input

Process Input P1

(Data Point
VDTLL PVCALC Parameters)

Variable Dead
Time Input P2

Equation A: One Lead and Two Lag Compensations

Equation B: Fixed Dead Time

Equation C: Variable Dead Time

Equation D: Variable Dead Time with Two Lag Compensations

Figure 7-7 — Functional Diagram, Variable Dead time with Lead Lag PV Algo 1316

7.7.6.2 Use

This algorithm is used for feedforward control and in process simulations. For additional
use information, see Equations C and D, under 7.7.6.4.
This algorithm can be used as the PV algorithm in a data point that uses the PID
Feedforward control algorithm (see 8.13.2), Figure 8-7.
In a typical feedforward application, the PV provided by this algorithm serves as the
feedforward PV. An operator can "cut out" this feedforward component by switching the
PVSOURCE to Man.

APM Control Functions & Algorithms 7-22 12/03

 7.7.6

7.7.6.3 Options and Special Features

Four Combinations of Delay and Lead-Lag Compensation

You select the combinations of delay, lead compensation, and lag compensation by
selecting Equation A, Equation B, Equation C, or Equation D when configuring the data
point. The equations function as follows:

• Equation A, Lead-Lag—A change in the input value (P1) is subjected to one lead
compensation and two lag compensations. If you specify a time constant of zero in the
Lead Compensation time constant, TLD, Lag Compensation time constants, TLG1, or
TLG2, the corresponding lead or lag compensation is suppressed. If you don't suppress
the lead compensation, you must use at least one lag compensation.

• Equation B, Fixed Dead Time—A change in the input value (P1) is delayed by a
user-specified time. This data point must be made inactive in order to change the dead-
time value (TD).

• Equation C, Variable Dead Time—A change in the input value (P1) is delayed by a
time period the duration of which varies as the inverse of P2-input value variations.
The variable time period is determined by P2, the C1 and C2 scale factors, and bias
values D1 and D2. The delay (or dead time) typically represents a delay in the process
that depends on some variable in the process, such as flow, feed rate, or a conveyer-
belt speed.

Equations C and D have a cutoff feature that can simulate situations like a conveyer
belt stopping. If the flow or speed value, represented by the P2 input, drops below a
limit that you configure in the CUTOFFLM parameter, the value of the delayed P1
signal (DP1) goes to zero. (DP1 is not an external parameter.) When P2 again exceeds
the CUTOFFLM value, DP1 resumes as a normal, delayed output. If you don't want
this feature, configure CUTOFFLM as NaN. Note that DP1 is subject to scale factor C
and bias value D. See 7.7.6.4.

Equation C can be used to produce a fixed delay time that can be changed while the
data point is active.

• Equation D, Variable Dead Time with Two Lags—A change in the input value (P1)
is delayed as with Equation C and then receives lag compensation as specified by one
or two time constants (TLG1, TLG2). This equation is useful for simulating a portion
of a process that can be represented by a dead time and one or two lags. The cutoff
feature applies as for Equation C.

APM Control Functions & Algorithms 7-23 12/03

 7.7.6
Dead-Time (Delay-Time) Calculation

The delay of the input values is accomplished by a process that has the effect of shifting
the values through a table in the APM's memory. Values are shifted from one location in
the table to the next, at intervals calculated to provide the desired delay. This is illustrated
in Figure 7-8.

Updated each time the

point is processed.

From the process or New table input at each

another data point P1 o o
NRATE TS interval
*
o
Delay Table Updated at each
NRATE TS interval.
*

Interpolator DP1

Maximum of 31 locations

Delayed P1 Output

New interpolated value

each time the data point
is processed (at each
TS interval)

Figure 7-8 — Variable Delay Time Functional Diagram 1317

For an example of the delay-table operation, suppose that the P1-input value has been
constant at 5.0 units for an hour. Assume that the specified delay time, TD, is 15 minutes
and that the data point is processed every second; Time Sample (TS = 1/60) min. as
determined by the SCANRATE parameter. At this time, the output of the interpolator is
5.0 units, all of the locations in the table contain a value of 5.0 units, and P1 contains a
value of 5.0 units.

Now suppose that the input to P1 suddenly changes to 6.0 units. The interval at which new
values are shifted through the table and the number of table locations in use have been set
up so that it takes 15 minutes for the new value of 6.0 units to appear at the output of the
interpolator.

Three sample calculations follow. The first shows how a fixed delay time is determined
(Equation B), the second shows how a variable delay time is determined, and the third
shows how a change in the P2 input changes the variable delay time.

APM Control Functions & Algorithms 7-24 12/03

 7.7.6
Fixed Delay-Time Example

1. The value in TS is 0.5 minutes and TD has been specified as 15 minutes.

2. NRATE, the table shift-rate factor, is calculated as follows:

TD 15
NRATE = (TS = = 1
* 30) (0.5 * 30)

3. NLOC, the number of table locations to be used, is

TD 15
NLOC = (TS = = 30 locations
*NRATE) (0.5 * 1)

4. The actual delay time is then recomputed as

TD = NLOC*NRATE*TS = 30*1*0.5 = 15 minutes

If the calculated values of NRATE and NLOC had resulted in fractions, the results would
have been rounded up to the nearest larger integer and the actual delay time would have
been slightly more than specified.

Where the TD is less than 30 times TS, NRATE always has a value of 1. In such cases, the
delayed output is a true, but delayed, representation of the corresponding input value.

Where the NRATE value is greater than 1, the output signal is interpolated to approximate
the earlier change in the input, by using the last output value and the value in the last
location in the table. This is an excellent approximation for typically smooth changes in
process values.

APM Control Functions & Algorithms 7-25 12/03

 7.7.6
Variable Delay-Time Example

1
1. The value in TS is 60 minutes. NLOC = 30.

2. Each time the data point is processed, a new variable delay time is calculated as
C1
TDNEW = (C2 + D1.
* P2) + D2

Assume the P2 input is 20.0 units and its scale factor is 0.05. Scale factor C1 is 30.0.
The biases, D1 and D2 both equal 0.
30.0
TDNEW = (0.05 + 0 = 30 minutes.
* 20.0) + 0

3. NRATE = (TSTDNEW =
30
= 60
* NLOC) (
1
60 * 30)

NLOC is configurable (range 2 - 30; in this example it is configured as 30)

4. Actual delay time is calculated as

1
TD = NLOC * NRATE * TS = 30 * 60 * 60 = 30 minutes.

NLOC is configurable (range 2 - 30; in this example it is configured as 30)

Now suppose the P2 input changes to 23.4 units.

Second Variable Delay-Time Example

1
1. The value in TS is 60 minutes.

C1 30.0
2. TDNEW = (C2 + D1 = (0.05 + 0 = 25.641
* P2) + D2 * 23.4) + 0
minutes.

3. NRATE = (TSTDNEW 25.641

= 1 = 51.282
* NLOC)
60 * 30

This is rounded to the nearest integer (not necessarily the next larger integer, as for a
fixed delay time), so
NRATE = 51.

APM Control Functions & Algorithms 7-26 12/03

 7.7.6
4. Actual delay time then is
1
TD = NLOC * NRATE * TS = 30 * 51 * 60 = 25.5 minutes.

NLOC is configurable (range 2 - 30; in this example it is configured as 30)

In the Second Delay Time Example, the exact delay specified by the input was 25.641
minutes.

Changing Dead-Time (Delay-Time) Parameters

Variable delay-time parameters C1, C2, D1, and D2 in Equations C and D can be changed
at a Universal Station while the data point is active. Note that the D1 value allows a
supervisor or engineer to add a fixed delay time to the total variable delay time.

The C1 and C2 parameters are used to specify the time scale of the P2 value. D1 can be
used to offset that scale. Note that the P2 value is inversely proportional to the variable
time delay. Where P2 represents a flow rate or speed, when the flow or speed decreases,
the time delay increases to simulate the effect of the reduced flow or speed.

Restrictions on Delay Time

The minimum fixed delay time (Equation B) is equal to TS, the processing interval in
minutes. Delay values greater than 32,000*TS are rejected.

For Equations C and D the minimum step-change in the TD value is equal to NLOC*TS.
This is also the value of the smallest dead time (delay time). If the TDNEW value is less
than zero, it is clamped to zero. Also, if TDNEW exceeds 32,000*TS, it is clamped to
32,000*TS.

Time-Constant Recommendations

We recommend that the processing rate of a data point that uses this algorithm and
Equation A or D must be at least ten times greater than the lead or lag break-point
frequencies, so, divided by lead break-point frequency) be less than or equal to 10, so,
TLG1 should be equal to or greater than 2 * TS
TLG2 should be equal to or greater than 2 * TS
|TLD| should be equal to or greater than 10 * TS
Both positive and negative lead times can be specified, so it is the absolute value of TLD
that must be equal to or greater than 10 * TS.
We recommend that the rate amplitude (lag break-point frequency divided by the lead
break-point frequency) be less than or equal to 10 so,
|TLD| should be equal to or less than 10 * TLG1.

APM Control Functions & Algorithms 7-27 12/03

 7.7.6

Using Equation C or D for a Fixed Delay Time

You can use these variable delay-time equations to attain a fixed delay time by setting the
value of C1 to 0 and adjusting the value of D1 to get the desired delay value. This permits
changes of delay time from a Universal Station while the data point is active, but the
resolution may be much less than using a fixed delay time (Equation B), where the delay
can be changed only by making the point inactive and then active again.

Restart or Point Activation

On a cold start, a warm start, and when the data point is activated, the lead-lag dynamics
are set to the steady state, and all values in the delay table are set to the current value of the
P1 input. PVCALC is calculated as follows:

PVCALC = C * P1 + D

Error Handling

For Equations C and D, if neither input has a bad-value status, but one or both has an
uncertain-value status, PVAUTOST is Uncertn. Equations A and B don't use the P2 input,
so for them, PVAUTOST is Uncertn only if the P1-value status (P1STS) is Uncertn.

For Equations C and D, if either input has a bad-value status, PVCALC becomes NaN and
the PVAUTOST is Bad. For Equations A and B, when P1STS is Bad, it causes PVCALC
to contain NaN and the PVAUTOST to be Bad.

When the input-value status is again normal or uncertain, the data point is initialized as for
a cold start under Restart or Point Activation, and the PVAUTO-value status becomes
normal, or uncertain, as appropriate.

7.7.6.4 Equations

You can select one of four equations when you configure a data point that uses the
Variable Dead Time with Lead-Lag Compensation PV algorithm:

Equation A—Lead Compensation with Two Lag Compensations

1 + TLD *s
PVCALC(s) = [C * (1 + TLG1 * s) * (1 + TLG2 * s) * P1(s)] + D

Equation B—Fixed Delay Time

DP1t = P1t-TD

PVCALC(s) = C * DP1 + D

APM Control Functions & Algorithms 7-28 12/03

 7.7.6
Equation C—Variable Delay Time

If CUTOFFLM does not contain NaN and if P2 is less than CUTOFFLM, DP1 = 0.
Otherwise, calculate DP1 as follows:

DP1t = P1t-TD

C1
TD = C2 * P2 + D2

PVCALC(s) = C * DP1 + D

Equation D—Variable Delay Time with Two Lag Compensations

C1
TD = C2 * P2 + D2 + D1

DP1t = P1t-TD

1
PVCALC(s) = [C * (1 + TLG1 * s) * (1 + TLG2 * s|) * DP1(s)] + D

Where:

PVCALC = The output of this algorithm. It is selected as the PV for this

data point when the PV source is AUTOmatic.

C = The overall scale factor. Default value = 1.0.

C1 = Scale factor, TDNEW denominator. Default value = 1.0.

C2 = Scale factor for P2. Default value = 1.0.

CUTOFFLM = Cutoff (zero-flow or zero-belt speed) limit. Default = 0.0.

D = Overall bias. Default value = 0.

DP1 = The delayed P1 value. Not accessible to Universal Stations

nor to user-written programs.

D1 = Bias value for the variable delay time. Default value = 0.

D2 = Bias for P2. Default value = 0.

P1 = The input value to which the delay and lead-lag
compensation are applied.

APM Control Functions & Algorithms 7-29 12/03

 7.7.6

P2 = The input value that changes the variable delay when

Equation C or Equation D is used.

s = The Laplace operator (notation only, not a parameter)

t = The present time (notation only, not a parameter)

t-TD = The present time minus the actual dead (delay) time
(notation only, not a parameter).

TD = The fixed time delay in minutes for Equation B. The actual

variable delay time in minutes for Equations C and D.
Default = 0.

TDNEW = The calculated new (ideal) delay time in minutes for

Equations C and D.

TLD = Lead-compensation time constant in minutes. 0 = no lead.

Default = 0.

TLG1 = Lag-compensation time constant 1 in minutes. 0 = no lag.

Default = 0.

TLG2 = Lag-compensation time constant 2 in minutes. 0 = no lag.

Default = 0.

Other parameters associated with the VDTLDLG algorithm is as follows (refer to the
Advanced Process Manager Parameter Reference Dictionary):

PVEQN NLOC (equations C and D)

APM Control Functions & Algorithms 7-30 12/03

 7.7.7

7.7.7 Totalizer (TOTALIZR)

7.7.7.1 Function

This algorithm provides a time-scaled accumulation of an input value. The input value is
typically a flow measurement. Either analog or pulse input can be selected through
parameter ACCTYPE. The time-base can be seconds, minutes, or hours.

Start
Stop
Operator or user- Reset PVCALC
written program TIMEBASE
Time-scaled
TOTALIZR
Target Value accumulation

Analog (HLAI)
Target-value
P1
flags
ACCTYPE
P2

PV AV

Pulse IOP

Figure 7-9 — Functional Diagram, Totalizer PV Algorithm 3369

The accumulation can be started, stopped, and reset by commands from a Universal
Station operator or from a user-written program. An operator or user-written program can
establish a target value for the accumulation. Status indicators are available to indicate that
the accumulation is near the target value, nearer to the target value, and is complete (has
reached or exceeded the target value).

For situations where the flow transmitter may not be precisely calibrated near the zero-
flow value, a zero-flow cutoff feature is provided that avoids accumulating negative flow
values. When the flow is below a user-specified cutoff value, the input value is clamped to
zero.

APM Control Functions & Algorithms 7-31 12/03

 7.7.7

7.7.7.2 Use

The Totalizer PV algorithm accumulates periodic measurements over time. It is principally

used to accumulate total flows, or in applications such as the measurement of ingredients
that are blended. The accumulated value can be used for control or just as process history.

An example of TOTALIZR's use in control is determining how full a tank is, so that the
flow into the tank can be shut off before it overflows. In such an application, the P1 input
to TOTALIZR would be the PV of PID-flow controller.

7.7.7.3 Options and Special Features

Typical Operation

The events in an operation that uses TOTALIZR might be as follows (see Figure 7-10):

• The target value, which represents the desired total volume, is specified to the AVTV
parameter in the TOTALIZR point, by an operator at a Universal Station or by a user-
written program.

NOTE
AVTV is displayed as the setpoint (SP).

• An operator or a user-written program issues a Reset command (using the

COMMAND parameter) to the TOTALIZR point. This sets any accumulation value
equal to RESETVAL.

• A Start command is issued to the TOTALIZR point. A logic slot or user program sets
the setpoint to some value.

• When the first "slowdown" or "near-target" flag (ADEV1FL) comes on, it is read by
logic or user program and reduces the setpoint.

• When the second "slowdown" or "near-target" flag (ADEV2FL) comes on, it is read by
logic or user program and reduces the setpoint.

• When the accumulation reaches the target value (AVTV), filling is complete and the
complete flag (AVTVFL) comes on. It is read by logic or user program and sets the
setpoint = 0.

APM Control Functions & Algorithms 7-32 12/03

 7.7.7

Target
Value
(PVTV)

AVDEV1FL
P1 TOTALIZER AVDEV2FL CL Block(s)
AVTVFL

SP
PID OP
PV

F Flow Transmitter

Liquid

Figure 7-10 — Using TOTALIZR to Fill A Tank 1311

Time-Base and Engineering-Units Scaling

The user specifies the time base in seconds, minutes, or hours, in parameter TIMEBASE.
This is the time base in which the flow measurement is made. For example, liters per
second. This parameter only applies when ACCTYPE = ANALOG.

Scale factor, C, can be used to convert from one set of engineering units to another, for
example, from gallons per minute to barrels per minute.

Commands, States and Command Flags

Commands can be issued to the data point that is using TOTALIZR from a Universal
Station or by a user-written program. These commands are written in the TOTALIZR
point's COMMAND parameter.

APM Control Functions & Algorithms 7-33 12/03

 7.7.7
The commands are as follows:

• None—No action.

• Start—Start the accumulation. STATE changes to Running.

• Stop—Stop the accumulation. STATE changes to Stopped.

• Reset—Reset the accumulated value to a user-specified value. This value is specified

in parameter RESETVAL. If the accumulator is running, it continues from the reset
value.

Command Flags

In addition to the above (enumerated) commands, explicit command flags are provided to
reset, start, or stop the totalizer.

• RESETFL — Off to On transition causes the totalizer to be reset. (See Accumulated

Value Before Reset for additional information.)

• STARTFL — Off to On transition causes the STATE of totalizer to be Running.

• STOPFL — Off to On transition causes the STATE of totalizer to be changed to

Stopped.

The above flags are program-access level, so they can be written to by a Logic Point or a
user-written program.

Accumulated Value Before Reset

The reset command sets the PVCALC parameter equal to the reset value (RESETVAL).
The value of PVCALC just prior to being reset is saved as the old accumulation value
(OLDAV). This allows other system functions using the totalized value to be able to reset
the totalizer without losing any "accumulation."

Range of Values, Clamping Option

The accumulated value has a normal range of PVEULO to PVEUHI, where PVEUHI
defines the point where the bar graph is at the 100% level, and PVEULO is the point where
the bar graph is at the 0% level.

APM Control Functions & Algorithms 7-34 12/03

 7.7.7
This algorithm will continue to totalize past PVEUHI until it reaches the value of
PVEXEUHI. When it reaches PVEXEUHI, the following occurs:
• If NoClamp was selected, the PV is set to BadPV and displayed as NAN.
• If Clamp was selected, the PV is flagged as uncertain and clamped to PVEXEUHI.
In either case, the algorithm continues to accumulate a value in PVCALC until it is reset,
regardless of the selection of NoClamp/Clamp.
Using Scientific Notation

Values are accumulated as integers, but displayed as real numbers. You can enter values
using scientific notation; for example, 1,000,000 can be entered as 1E6. If the accumulated
value exceeds the limit of displayable characters, it will be displayed in scientific notation.
Near-Zero Cutoff

To prevent accumulation of negative flow values, where the flow transmitter may not be
precisely calibrated near zero flow, you can specify a cutoff value in parameter
CUTOFFLM. When the P1 value is below CUTOFFLM, it is replaced by zero. You can
eliminate this feature by specifying NaN in CUTOFFLM.
Target-Value Flags

The target value can be specified by an operator or a user-written program that is stored in
AVTV. This feature can be disabled by storing NaN in AVTV.
When the accumulated value in PVCALC is equal to or greater than AVTV, the target-
value-reached flag, AVTVFL, goes to On, indicating that the accumulation is complete.
Even if the accumulator has stopped, this check is made on each processing pass.
You can specify two other trip points in AVDEV1TP and AVDEV2TP, as deviations from
AVTV. Each of them is associated with a flag:
AVDEV1FL trips when
PVCALC > AVTV - AVDEV1TP

AVDEV2FL trips when

PVCALC > AVTV - AVDEV2TP

When the PVAUTOST of the accumulated value is Bad, AVTVFL, AVDEV1FL, and
AVDEV2FL are all Off.

APM Control Functions & Algorithms 7-35 12/03

 7.7.7
Bad-Input and Warm-Restart Options

You can configure equations A through F for this algorithm, but instead of specifying the
calculation, they specify combinations of the following five options:
• Use Zero—When the accumulator is running, if the input status P1STS (or P2STS for
Pulse IOP) is Bad, the input value is replaced by zero and the accumulation continues
with a PVAUTOST of Uncertn.
When the input status is Normal, PVAUTOST remains Uncertn until a reset command
is received. No special action by the operator is required.
• Use Last Good Value—When the accumulator is running, if the input status is bad,
the input value is replaced by the last good value and the accumulation continues with
PVAUTOST as Uncertn. When the input status is Normal, PVAUTOST remains
Uncertn until a Reset command is received. No special action by the operator is
required.
• Set PVAUTOST Bad and Stop—When the accumulator is running and the input
status is bad, the value in PVCALC becomes NaN, PVAUTOST goes Bad, and the
accumulator is stopped. If the PVSOURCE is Auto, a bad-PV alarm is generated.
When the input status is again Normal, PVAUTOST remains Bad until the
accumulator is started again. To restart the accumulation, the operator should estimate
its value and use the Reset command (see Commands, States and Command Flags)
to establish that value, then use the Start command to restart the accumulation. The last
accumulated value before the status went bad is in LASTPV.
• Continue After a Warm Restart—On a warm restart when the accumulator is
running, the accumulation continues from the last PVCALC value. The PVAUTOST
goes to uncertain (UNCERTN) and remains so until a Reset command is received.
When the Pulse Input IOP is used (ACCTYPE = PULSE), accumulation continues
with the accumulated value count (AV) obtained from the IOP. The totalizer assumes
that exactly one rollover of the IOP count has occurred, if necessary. The PVAUTOST
goes to UNCERTN and remains so until a Reset command is received.
• Set PVAUTOST Bad and Stop After a Warm Restart—On a warm restart when the
accumulator is running, the value in PVCALC becomes NaN, PVAUTOST goes Bad,
and the accumulation is stopped. The operator must intervene to restart the
accumulator.

APM Control Functions & Algorithms 7-36 12/03

 7.7.7
These options are selected as follows:
Equation Bad Input Handling Warm Restart

A Use Zero Continue

B Use Last Good Value Continue
C Set Bad and Stop Continue
D Use zero Set Bad and Stop
E Use Last Good Value Set Bad and Stop
F Set Bad and Stop Set Bad and Stop

If the accumulator is stopped, the input status is ignored. If the accumulator is stopped on a
warm restart, no special action by the operator is required.

Restart or Point Activation

When the TOTALIZR data point is activated, the PVCALC value becomes NaN,
PVAUTOST goes Bad and the accumulator state is Stopped. If the PVSOURCE is Auto,
this causes a bad-PV alarm and the operator must re-establish normal operation.

The processing that takes place for a warm restart is described under Bad Input and
Warm-Restart Options.

Error Handling

PVAUTOST is Uncertn when

• The input status (P1STS or P2STS) is Uncertn.

• The input status is Bad and the "use zero" or "use last value" (Equation A, B, D, or E)
is configured (see Bad-Input and Warm-Restart Options).

• The data point is in a warm restart and the continue option (Equations A, B, or C) is
configured (see Bad-Input and Warm-Restart Options).

A Reset command is needed to return PVAUTOST status to Normal, provided the input
status is Normal.

PVCALC contains NaN and the PVAUTOST is bad when

• The input status is Bad and the "set bad and stop" (Equation C or F) is configured.

• The data point is in a warm restart and is configured for "set bad and stop" (Equations
D, E, or F) is configured.

A Reset command is needed to return PVAUTOST to Normal, provided the input status is
Normal.

APM Control Functions & Algorithms 7-37 12/03

 7.7.7
7.7.7.4 Equations

Configure one of Equations A through F for a TOTALIZR data point equation specifying
the operating bad-input and warm-restart options according to Bad-Input and Warm-
Restart Options.
Analog Operation—
For all equations, when the accumulator is running, the accumulated value in PVCALC is
calculated as follows:
PVCALC(i) = PVCALC(i-1) + C * (TIME-SCALE) * Pn

Where
PVCALC(i) = The output of this algorithm from the current pass. It is
selected as the PV for this data point when PVSOURCE is
Auto.
PVCALC(i-1) = The accumulated value at the end of the last processing pass
for this point.
C = The scale factor. Can be used to convert from eng. units to
different eng. units. Default value = 1.0
(Time-scale) = TS*60 if TIMEBASE contains Seconds.
TS if TIMEBASE contains Minutes.
TS/60 if TIMEBASE contains Hours.

TS = The data-point processing interval in minutes.

Pn = The input value is a typical flow rate.

Pulse Input—See the discussion on pulse input operation.

7.7.7.5 Pulse Input Operation

If pulse is selected via parameter ACCTYPE, operation is the same, except input from the
Pulse IOP is supported as described below (refer also to the Pulse IOP description in
Section 2.7).
As Figure 7-9 indicates, P1/P2 input is from the Pulse IOP. Normally the P2 input (AV) is
used (see PV/AV Selection). AV is the accumulated value from the pulse IOP. It is a 32 bit
unsigned integer and used to determine volume. This method is more precise than if the
Pulse IOP rate value is used. Error handling selected by Equations A through F reference
the P2 input status.
The PV Totalizer algorithm contains a single user-configurable constant (C) —
PVCALC = C * DELTA_AV + PVCALC_LAST_SAMPLE

APM Control Functions & Algorithms 7-38 12/03

 7.7.7
7.7.7.6 Configuration

When configuring the PV Totalizer algorithm for pulse operation, select ACCTYPE =
PULSE. Then, define the pulse input source, P1SRC(1) to be the PV parameter of the PI
IOP. The APMM software uses the entity specified for P1SRC(1) to establish the
algorithm’s second input (P2) except that it uses the parameter ID of AV.

7.7.7.6.1 PV/AV Selection

Either of the parameters AV or PV is available at the input of the Regulatory PV Totalizer

algorithm. Normally AV is used, but only if all the following conditions are true—

The Pulse IOP is running

The Point is active
The IOP PV is not in lo cutoff
The IOP PV is not clamped
The IOP PV source is AUTO
There are no soft failures against the IOP slot

7.7.7.7 Parameters

Other parameters associated with the TOTALIZR algorithm are as follows (refer to the
Advanced Process Manager Parameter Reference Dictionary):

P1STS (analog input) P2STS (pulse input) PVCALC PVEQN

AVTV ACCTYPE

7.7.8 General Linearization (GENLIN)

7.7.8.1 Function

This algorithm calculates a PV that is a function of the input. The function can be any that
can be represented by up-to-12 continuous, linear segments. You specify the base value
and slope of each segment. The input is compared with the input range of each segment
and the output is set at the intersection of the input with the appropriate segment. See
Figures 7-11 and 7-12.

(Data Point
P1 GENLIN PVCALC
Parameter)

Figure 7-11 — Functional Diagram, General Linearization PV Algorithm 1307

APM Control Functions & Algorithms 7-39 12/03

 7.7.8
7.7.8.2 Use

This algorithm is typically used to provide a linearized PV (in engineering units) for a
sensor with a nonlinear characteristic. This algorithm can also be used to characterize
functions of a single variable, such as heat transfer vs flow rate, or efficiency as a function
of load. The algorithm is particularly useful when the relationship of the input to
engineering units is empirically determined.
This algorithm supplements the standard linearization functions that are provided in the
IOPs for standard temperature sensors and differential flow meters.

7.7.8.3 Options and Special Features

Restart or Point Activation

On a cold or warm restart, or when a data point using this algorithm is activated, PVCALC
is recalculated the next time this data point is processed.

Error Handling

If P1STS is Uncertn, PVAUTOST status becomes Uncertn.

If P1STS is Bad or if any of the segment coordinates (INi or OUTi) contains NaN,
PVAUTOST becomes Bad.
If any of the segment coordinate values (INi or OUTi) contains NaN, a configuration alarm
is generated.

Changing Parameters through a Universal Station

The SEGTOT, INi, and OUTi parameters can be changed through a Universal Station only
if the data point that uses the GenLin algorithm is made inactive.

Parameter—Value Restrictions

The input coordinate value parameters must be specified in ascending order from the
smallest value to the largest.

APM Control Functions & Algorithms 7-40 12/03

 7.7.8

OUT3 100 -

90 -

80 -
Solution D
70 -

60 -
PVCALC

50 - SEGTOT = 3
OUT2 Solution A
40 -
Solution C
30 -

OUT1 20 -
Solution B
10 -

OUT0 0 -

0 10 20 30 40 50 60 70 80 90 100

IN0 IN1 IN2 IN3

IN0 = 0.0 OUT0 = 0.0 Beginning of 1st segment

IN1 = 30.0 OUT1 = 20.0 End of 1st segment
IN2 = 55.0 OUT2 = 45.0 End of 2nd segment
IN3 = 85.0 OUT3 = 100.0 End of 3rd segment

Solution A (P1 = IN2):

PVCALC = OUT2 = 45.0

Solution B (P1 > IN1):

OUT1 - OUT 0 20 - 0
PVCALC = * (P1 -IN0) + OUT0 =30 - 0 * (20 - 0) + 0 = 13.33
IN1 - IN0

Solution C (P1 intersects any but 1st and last segment):

OUT(i+1) - OUTi 45 - 20
PVCALC = (P1 - INi) + OUTi = (45 - 30) + 20 = 35.0
IN(I+1) - INI * 55 - 30 *

Solution D (P1 intersects the last segment):

OUTsegtot - OUT(segtot - 1)
PVCALC = *[P1 - IN(segtot - 1)] + OUT(segtot -1)
INsegtot - IN(segtot - 1)

100 - 45
=
85 - 55 * (70 - 55) + 45 = 72.5

Figure 7-12 — Example of GENLIN Algorithm Operation 1308

APM Control Functions & Algorithms 7-41 12/03

 7.7.8
Extension of First and Last Segments

The first and last segments are treated as if they indefinitely extended, so if P1 is less than
IN0 or greater than INsegtot (see 7.7.8.4), PVCALC is computed by assuming that the
slope of the appropriate segment continues to the intersection point.
7.7.8.4 Equation

Each time this algorithm is processed the input value P1 is compared with each segment,
starting with the first and continuing until a segment is found that intersects with the input.
When that segment is found, PVCALC is calculated as follows:
• If the P1 value is exactly equal to the input value at the beginning of any segment (P1 =
INi, for i in a range from 0 to the value in SEGTOT),
PVCALC = OUTi

• If P1 intersects the first segment (P1 < IN1),

OUT1 - OUT0
PVCALC = IN1 - IN0 * (P1 - IN0) + OUT0

• If P1 intersects any segment except the first one or the last one [INi < P1 < IN(i+1) for
any i from 1 to segtot-2],
OUT(i+1) - OUTi
PVCALC = IN(I+1) - IN1 * (P1 - IN1) + OUT1

• If P1 intersects the last segment [P1 > IN(segtot-1)],

OUTsegtot - OUT(segtot-1)
PVCALC = * [P1 - IN(segtot-1)] + OUT(segtot-1)
IN segtot - IN(segtot-1)

Where:
PVCALC = The output of this algorithm. It is selected as the PV for this
data point when the PV source is AUTOmatic.
P1 = The input value.
IN(i) = Input value at the beginning of the intersecting segment.
IN(i+1) = Input value at the end of the intersecting segment.
OUT(i) = Output value at the beginning of the intersecting segment.
OUT(i+1) = Output value at the end of the intersecting segment.
segtot = A subscript indicating the user-entered value in SEGTOT.

Other parameters associated with the GenLin algorithm are as follows (refer to the
Advanced Process Manager Parameter Reference Dictionary).

P1STS PVCALC SEGTOT

APM Control Functions & Algorithms 7-42 12/03

 7.7.9

7.7.9 Calculator (CALCULTR)

The calculator algorithm allows the user to write an equation to compute the PV and up to
four intermediate results. The result from evaluating the expression is stored into
PVCALC, which is then processed like any other PV algorithm. See Figure 7-13.

P1
P2
P3 (Data Point
P4 CALCEXP PVCALC
Parameters)
P5
P6

Accepts up to six inputs (POINT.PARAMETER).

Equation may be up to 40 characters long.
Up to 4 intermediate results
FORTRAN-like syntax rules
High Select; Low Select; Average Select and Middle of 3 Select support

Figure 7-13 — Functional Diagram, PV Algorithm CALCULTR 2097

7.7.9.1 Function

The equation is specified at the time of point building and is loaded from the DEB without
additional steps such as compilation or linking. Up-to-six inputs can be configured and
stored into the destination parameters P1, P2 . . . P6.

The following general guidelines apply.

• The equation can be up to 40 characters long.

• FORTRAN-like syntax rules apply.

• Up to 5 levels of nesting of expressions.

• Free format reals and mixed real and integer calculations permitted.

• Up to four intermediate results.

• The result of any expression that has no "equate" associated with it is stored into
PVCALC.

• On point activation or warm restart PVCALC is initialized to the P1 input.

APM Control Functions & Algorithms 7-43 12/03

 7.7.9
• The following operators are supported:
Operator Associated Symbol

Divide /
Multiply *
Subtract -
Add +

• The following arithmetic functions are supported:

Function Associated Symbol

Absolute ABS
Square SQR
Square Root SQRT
Natural Logarithm LN
Base_10 Logarithm LOG
Exponent EXP
Sine SIN
Cosine COS
Tangent TAN
Arc-tangent ATAN

• In addition, the following special functions are supported:

Function Associated Symbol

High Select MAX

Low Select MIN
Average Select AVG
Middle of 3 MID3

• Arithmetic assignment statement:

Equate =

• Other

Separator ;

7.7.9.2 Use

This algorithm can be used to perform any calculation or arithmetic function on up to six
inputs, using up to four intermediate results. Additionally is can be used as a selector
algorithm as noted above (see also 7.7.9.3 Options and Special Features).

APM Control Functions & Algorithms 7-44 12/03

 7.7.9

7.7.9.3 Options and Special Features

• The user can configure up-to-six inputs, using the "Tagname.Parameter" format for
PISCRC(n). The destination inputs can be assigned, using PIDSTN(n) for P1 through
P6.

• Up to four intermediate results can be calculated, for example:

C1=<expr_1>; C2=<expr_2>; C3 =<expr_3>; C4=<expr_4>;<expr_5>

The result of expr_5 is stored in PVCALC (because it has no equate associated with it).
There is no restriction on the order in which the sub equations and the expression for
PVCALC are specified.

If C1-C4 are expressions, they are recalculated every time the algorithm is processed.

• If it is necessary, or desirable, to key user configurable constants into the equation, C1-
C4 can be useful. C1-C4 can then be entered or modified by an operator through the
detail displays, or by logic slots, or user program.

• The equation can comprise up to 40 characters including the subequations.

• Can be loaded from the DEB without extra linking and compiling.

• FORTRAN syntax rules apply; up-to-five levels of nesting of expressions.

• HI, LO, and AVG functions may have any number of inputs including constants.

Error Handling of Bad-Inputs and Uncertain Values

If the calculated value of PVCALC is "bad," PVAUTOST is marked Bad. If the final value
of PVCALC is a normal number, PVAUTOST is marked Uncertn if any input that is used
in the calculation is uncertain or bad; otherwise it is set equal to Normal.

If the HI, LO, and AVG functions have bad inputs, they are ignored in the computation; if
all inputs are bad, the result is marked bad. On MID3 function, if only one input is bad, the
result is set equal to the average of the other two.

APM Control Functions & Algorithms 7-45 12/03

 7.7.9

7.7.9.4 Equations

The equation can be up to 40 characters long. It is entered into the Parameter Entry Display
in the port for the parameter CALCEXP. You can configure up to four intermediate
expressions. The result of an expression not having an "equate" associated with it is stored
in PVCALC.

Examples of use of this algorithm's equation:

(180.0/(.15*P1)) + (P2+P3*LOG(P4))

C1=P1*P2;C2=P4*MAX(0,C1,100);SQRT(C2*10)

MAX (MID3(P1,P2,P3), MID3(P4,P5,P6)

(P1 * P2)/C1

APM Control Functions & Algorithms 7-46 12/03

 8

REGULATORY CONTROL POINT

Section 8
This section describes the functions available in the Regulatory Control point. The functions are
described first, and then are followed by detailed descriptions of the algorithms. Definitions of the
parameters mentioned in this section can be found in the Advanced Process Manager Parameter
Reference Dictionary.

8.1 FUNCTIONS
Regulatory Control (RegCtl) points are used to perform standard control functions by
executing the algorithms that have been configured. Each control algorithm includes a
wide range of configurable options to allow implementation of complex control strategies
by a simple menu-select process. For example, initialization and windup protection are
inherently provided for all point interconnections. Also, the capability to ramp a setpoint
(by operator entry of a target value and ramp time) is configurable. Predefined and custom
displays are available to support these control strategies. These standard support functions
significantly simplify the implementation and use of sophisticated multiloop control
strategies. Increasingly advanced control strategies become practical as a result of the ease
of APM configuration.
The RegCtl point supports the following algorithms:
PID (Pid)
PID with Feedforward (PidFf)
PID with External Reset Feedback (PidErfb)
Position Proportional (PosProp)
PID Position Proportional (PIDPosPr)
Ratio Control (RatioCtl)
Ramp Soak (RampSoaK)
Override Selector (ORSel)
Auto Manual (AutoMan)
Incremental Summer (IncrSum)
Switch (Switch)
Null (Null)
Detailed descriptions of these algorithms can be found in this section beginning with
paragraph 8.13.
Figure 8-1 is a functional diagram of the RegCtl point.

8.2 CONTROL INPUT CONNECTIONS

Control input connections are typically used to assign "noninitializable" inputs to the
configured control algorithm. They can be used to assign initializable inputs, but if
initialization and windup protection are required, a control output connection from the
primary point must be used.

APM Control Functions & Algorithms 8-1 12/03

 8.2

The number of control input connections (NOCINPTS) and the destination parameter
(CIDSTN) for each connection are defaulted based on the noninitializable inputs required
by the control algorithm. (Refer to the individual control algorithm configuration form for
the destination parameters within each algorithm.) The control input connection-source
parameter CISRC allows the user to specify the source of the input using the
"Tagname.Parameter" format.

The inputs can be obtained from any source parameter that is a real number, an integer, or
a Boolean state. (Boolean states are treated as real numbers by the algorithm. The Off state
is equal to a real number of 0.0; the on state is equal to 1.0). For all RegCtl algorithms
except PIDERFB, the point's control output connections are also considered input
connections because the RegCtl point reads the output status before writing to it. A RegCtl
point can have a maximum of seven input and output connections that obtain inputs from
I/O Processors in the same APM.

Generally, initializable inputs are stored with control output connections at the primary
data point, and no input connections are required; however, in some cases it may be
required to obtain initializable inputs with input connections (for example, when
initialization and windup protection are not needed). To achieve this, the number of control
inputs is allowed to be increased based on the initializable inputs of the control algorithm.

8.3 PV SOURCE SELECTION (Pid, PosProp, and RatioCtl Algorithms)

The source of the PV can be an analog input point, a PV algorithm, a Universal Station, or
a user-written program. It is specified by the PVSOURCE parameter, whose value can be
changed by an operator, a supervisor, an engineer, or a user-written program. The
PVSOURCE parameter is configurable only if the data point has been configured as a full
point. PVSOURCE can have one of the following values:
• Auto—PV is received from an analog input point or a PV algorithm. The value is in
PVAUTO and its status is contained in PVAUTOST. During normal operation, the PV
source is Auto, and the PV and its value status (PVSTS) become equal to PVAUTO
and PVAUTOST, respectively, before PV range checks are made. When the PV source
is changed from Auto to Man or Sub, the PV remains at the last value until it is
changed by the operator (Man) or a program (Sub), so it doesn't "bump." In Man or
Sub, the status in PVSTS is Uncertn. When the PV source is changed from Man or Sub
to Auto, the PV immediately goes to the PVAUTO value. This might cause a bump in
the value unless it is changed gradually to the value in PVAUTO before changing the
source.
• Man—The PV is entered by an operator, supervisor, or engineer at a Universal Station.
• Sub—The PV is entered by a user-written program. A program can store a bad value in
PV, and if it does, PVSTS becomes Bad.

APM Control Functions & Algorithms 8-2 12/03

 8.3

You can prevent PV source changes by entering OnlyAuto for the PVSRCOPT parameter.
This fixes the source as AUTO and the parameter PVSOURCE is removed from the point.
Configuring All in PVSRCOPT allows normal PV source selection.

PV (Input Value)

Input CONTROL INPUT

Parameters PROCESSING

PV SOURCE
SELECTION
Pid, PosProp, ALL OTHER
and Ratio Ctl PV ALARM
DETECTION ALGORITHMS
Algorithms

EXTERNAL MODE
SWITCHING

INITIALIZATION
LOGIC

TARGET VALUE
PROCESSING OR
DEVIATION
ALARMING
Pid, PosProp,
and Ratio Ctl PV ALL OTHER
Algorithms TRACKING ALGORITHMS

DEVIATION
ALARMING

CONTROL
ALGORITHM
CALCULATION

CONTROL
OUTPUT OP (Output Value)
PROCESSING

ALARM
DISTRIBUTION

Figure 8-1 — Regulatory Control Point, Functional Diagram 2069

APM Control Functions & Algorithms 8-3 12/03

 8.4

8.4 MODES

The following operating modes are applicable to the RegCtl point (refer to Figure 8-2):

• Manual (Man)—provides the operator or the discontinuous program with direct

control over the output value of the data point, regardless of any automatic control
strategy.

• Automatic (Auto)—output value is computed by the configured RegCtl algorithm, and

the setpoint comes from the local setpoint (LSP) location in the RegCtl point. An
operator or a discontinuous program can change the setpoint value.

• Cascade (Cas)—data point receives its setpoint value from a primary data point.

• Backup Cascade (Bcas)—local cascade mode where the RegCtl point receives its
setpoint from a primary data point even though the entry for the RCASOPT parameter
is Spc, DdcRsp, or Rsp (where the AM provides the setpoint). In this way, should the
AM or the NIM fail, the control strategy will shed to the local cascade mode.

Separate flags are provided to indicate if the current mode is manual (MANMODFL), auto
(AUTMODFL), or if the mode attribute is Oper (OPRATRFL). The modes and mode
attributes can be used in conjunction with the logic slots to implement interlocks.

8.4.1 Mode Attribute

The mode attribute denotes who has the authority to change certain parameters of a data
point, and is established through parameter MODATTR. The mode attributes are as
follows:

• Operator—Operator can supply the setpoint, output value, mode, ratio, and bias for a
data point (operator-access level).

• Program—Program can supply the setpoint, output value, mode, ratio, and bias for a
data point (program-access level).

• None—The mode does not have an attribute.

At a Universal Station, the mode attribute is displayed next to the mode of the data point.
If the mode attribute is program, a "P-" is displayed to the left of MODE. If the mode
attribute is Operator, blanks are displayed to the left of MODE.

An access level of Ccont (Continuous Control) allows supervisory control from an LCN
module, such as the AM, to change the setpoint, output value, and mode of a data point.

APM Control Functions & Algorithms 8-4 12/03

 8.4.1

OP (from AM)
Ddc
DdcRsp Spc

Rsp
RCASOPT

Cas
PV (from Program) Bcas Auto

Man
PV (from Operator) Sub MODE
Man
Configured Auto
PVAUTO
PV Connection (CISRC) PVSOURCE
REGULATORY MODE
CONTROL OP OP
POINT Cas or Auto
SP
Man

MODE MODATTR

Prog
Cas Auto None
Oper
Configured
SP Connection (CISRC)

MODE
Bcas Auto

Man
Cas

RCASOPT
Spc Rsp

DdcRsp
Ddc

SP (from AM)
None
SP (from Operator)
Oper MODATTR
SP (from Program)
Prog

OP (from Operator)
OP (from Program)

Figure 8-2 — Mode Structure 2081

APM Control Functions & Algorithms 8-5 12/03

 8.4.2

8.4.2 Normal Mode

The normal mode is the mode that is copied into the MODE parameter when the operator
presses the NORM button at the Universal Station. Also at that time, the content of the
NMODATTR parameter is copied into the MODATTR parameter. This then becomes the
mode for the data point. The possible entries for the normal mode are None, Man, Auto,
Cas, and Bcas.

8.4.3 Normal Mode Attribute

The normal mode attribute is the attribute that is copied into the MODATTR parameter
when the NORM button is pressed. The possible entries for the NMODATTR parameter
are Operator, Program, and None

8.4.4 Remote Cascade Handling (PID Algorithms)

The APM supports supervisory or DDC control for the PID algorithms from any remote
device such as a computer (through the CG) or the AM. If the remote cascade connection
is coming from a regulatory data point in the AM, it handles everything automatically;
however, in all other cases (including the continuous CL programs in the AM directly
writing to the APM), the user must ensure that the following conditions are handled:
• Remote device must use the continuous control access-level (Ccont) parameter for
writing to the SP, OP, and MODE parameters.
• Remote device must also handle mode changes for closing the cascade.
• Initialization to ensure bumpless mode transfers.
• Windup protection.

8.4.4.1 Remote Cascade Options

The following remote cascade options are provided by the RCASOPT parameter:

• Supervisory Control (Spc)—This option is configured by setting RCASOPT to Spc.

The AM control strategy writes to the setpoint of the RegCtl point, subject to the
setpoint limits, when the RegCtl point is in Cas mode.

• Direct Digital Control (Ddc)—This option is configured by setting RCASOPT to

Ddc. The AM control strategy writes to the OP output of the RegCtl point, when the
RegCtl point is in Cas mode. The output limits are not applicable in this case. The SP
cannot be written by the AM control strategy to the RegCtl point. If the control
algorithm is a PID type and is configured for PV tracking, the SP is set equal to the PV
when in Cas mode.

APM Control Functions & Algorithms 8-6 12/03

 8.4.4

• Direct Digital Control with Remote Setpoint (DdcRsp)—This option is available for
only PID-type algorithms. It is configured by setting RCASOPT to DdcRsp. The AM
control strategy writes directly to the OP output of the RegCtl point when it is in Cas
mode. The output limits are not applicable. The AM can also write to the SP of the
RegCtl point subject to the setpoint limits. PV tracking is not performed in Cas mode.
This option is used primarily when a single PID controller in the APM is used to back
up a higher level control strategy running in the AM. The higher level control strategy
writes to the OP and also provides the SP for the backup control strategy.

• Remote Setpoint (Rsp)—This option is available for only PID-type algorithms and is
configured by setting RCASOPT to Rsp. The AM control strategy writes to the SP via
an AM general output connection, subject to the setpoint limits, when the RegCtl point
is in the Auto mode and it is being initialized by its secondary (i.e. INITMAN flag is
On). PV tracking is not performed in Auto mode when INITMAN is On, if Rsp is
selected.

The Rsp option is used primarily in a cascade control strategy where a RegCtl point is used
to backup a higher level control strategy running in the AM, and the higher-level control
strategy provides the SP for the backup control strategy. In the backup strategy, the
primary PID would be configured for the Rsp option (allowing the AM to specify the
backup SP), and the secondary would be typically configured for Ddc or Spc control.

8.4.4.2 Remote Cascade Request

When the RCASOPT parameter for the RegCtl point is configured for Spc, Ddc, or
DdcRsp and the operator at the Universal Station or a discontinuous user program (e.g. a
sequence program) tries to change the mode to Cas, the remote cascade request flag
(CASREQ) is set to On, but the actual mode is left unchanged. The actual mode is changed
to Cas only when

• The AM control strategy explicitly writes the mode to Cas (it should do this only after
seeing a remote cascade request from the secondary), or

• If Spc is entered for the RCASOPT parameter, and the AM control strategy writes to
the setpoint, or

• If Ddc or DdcRsp is entered for the RCASOPT parameter, and the AM control
strategy writes to the output value OP of the RegCtl point.

After CASREQ has been set to On, any mode change causes CASREQ to be set to Off.

APM Control Functions & Algorithms 8-7 12/03

 8.4.4
8.4.4.3 Remote Cascade Shed

The remote cascade shed mechanism in the APM allows the user to substitute the local
backup control strategy in the APM for the AM control strategy if the AM or NIM fails.
When a RegCtl point that is configured for Spc, Ddc, or DdcRsp control is in Cas mode
and the SP (if Spc) or the OP (if Ddc or DdcRsp) is not updated by the AM within a
predefined time, the AM or the NIM is assumed to have failed. The backup control
strategy is substituted by means of changing the mode to a preconfigured backup mode.
The maximum time allowed between updates is specified by SHEDTIME (in seconds) and
the backup mode is specified by SHEDMODE. Shedding to the backup mode can be
disabled by setting SHEDTIME to 0.
When the mode is shed to the preconfigured shed mode, the remote cascade shed flag
(RCASSHED) is set to On (mainly for indication at the Universal Station). Any
subsequent mode changes automatically set the RCASSHED to Off. The remote cascade
request flag is also set to On, which allows the AM to resume control at a later time
without operator intervention.

8.4.4.4 Bad PV/Mode Shed

The Regulatory Control parameter BADCTLOP determines if the mode sheds to manual
on detection of a bad PV (or bad CV for algorithms that do not have a meaningful PV). For
the definition of a bad PV, refer to BADPVFL in the Parameter Reference Dictionary.
This function does not apply to the RampSoak, IncrSum, or RatioCtl algorithms.

The BADCTLOP parameter is configured on a per point basis as shown in the following
table:
Table 8-1 — Bad PV/Mode Shed
BADCTLOP SHED To Mode Ext. Mode
Selection Output (Mode) Attribute Switching Comments

No Shed Held Held N/A N/A Point resumes

control after
initializing on
PV recovery.

SHED HOLD Held Point is not

automatically
returned to
the previous
mode before
SHED LOW -6.9% shed to manual.

Manual Operator Disabled Operator is not

allowed to return
SHED HIGH 106.9% to the previous
mode until the
bad control
condition
SHEDSAFE SafeOp clears.

APM Control Functions & Algorithms 8-8 12/03

 8.5

8.5 SAFETY SHUTDOWN

This option allows the user to implement safety interlocks that effectively shut down a
single control loop. When the shutdown flag (SHUTDOWN) is set to On by a user-written
program, the mode and the mode attribute are changed to Man and Oper, respectively, and
the OP output is set equal to a predefined safe output value (SAFEOP). Further, the
external-mode-switching enable state (ESWENBST) is disabled, if it is currently enabled.
As long as the shutdown flag is On, the MODE, MODATTR, ESWENBST, and OP
parameter values cannot be changed. When the shutdown flag is set to Off, the control
loop must be manually restarted.

A Logic Point or CL program must be used to reset the Safety Shutdown Flag (from ON to
OFF).

If the point is already red tagged when the shutdown flag is turned On, the output value is
not changed. Typically, the safe output value can be configured as 0% (if the valve is fully
closed) or 100% (if valve fully open). In some cases it may be important to just hold the
last value. This can be achieved by setting the SAFEOP parameter to NaN.

The shutdown flag cannot be initiated from the Universal Station.

8.6 EXTERNAL MODE SWITCHING

External mode switching (EMS) is typically used to establish mode interlocks or, under
certain process conditions, to restrict the use of a mode that invokes a higher level of
control. External mode switching is an option and can be configured by entering Ems for
the EXTSWOPT parameter. Mode changes made through external mode switching have
no effect on the mode attribute of the data point, or on the normal mode and normal mode
attribute of the point. When a mode change is made, the last values of the normal mode
and normal mode attribute parameters stay in effect.

Each regulatory data point has three parameters (ESWMAN, ESWAUTO, and ESWCAS)
that are used as flags to indicate the mode to which the point has been switched.

When external mode switching is enabled by the operator or the program by setting the
ESWENBST parameter to Enable, the operator and the program are prevented from
changing the mode of the data point when the point is in the ESWMAN, ESWAUTO, or
ESWCAS mode as indicated on Table 8-2; however, the operator or the program can
disable external mode switching at any time by entering Disable for the ESWENBST
parameter.

APM Control Functions & Algorithms 8-9 12/03

 8.7

Table 8-2 — Mode-Switching Operation

ESW Parameters' Can Mode Be

EXTSWOPT (Note 1) Effective New Mode Changed By
= Ems MAN AUTO CAS Operator or Program?

No X X X Last Mode Requested Yes

F F F Previous Mode (Note 2)
Yes T X X Man No
F T X Auto (Note 3)
F F T Cas (Note 3)

Notes :
1. MAN is ESWMAN, AUTO is ESWAUTO, and CAS is ESWCAS, T = True, F = False, and X = don't care.
2. Previous Mode is the mode when the point was last processed.
3. If the effective new mode is not legal for the control algorithm, the mode doesn't change.

8.7 SETPOINT HANDLING

Setpoint handling takes place only if the configured control algorithm requires a setpoint.
Setpoint-handling functions are as follows:

• Setpoint (SP) limits

• SP Target-Value processing

• PV Tracking

• Deviation Alarming

• Advisory Deviation-alarm processing

• Ratio and bias options

• Setpoint Restrictions

APM Control Functions & Algorithms 8-10 12/03

 8.7.1
8.7.1 Setpoint (SP) Limits (Pid, PosProp, PIDPosPr, and RatioCtl
Algorithms)

Setpoint limit parameters SPHILM and SPLOLM prevent setpoint values from exceeding
user-configured high and low limit values. These limits are configured in the same
engineering units as the SP and must be within the SP range plus extensions. Crossover of
setpoint limits is not allowed. The configured setpoint limits also apply to the advisory-
target value.

Setpoint limits are observed in initialization calculations. If the limits are violated by the
SP value, antireset windup-status propagation is invoked.

8.7.2 SP Target-Value Processing (Pid, PosProp, PIDPosPr, and RatioCtl

Algorithms)

This option allows a Universal Station operator or a user-written program to "ramp" the
setpoint from the current value to a new value over a period of time. The option is
configured through the Data Entity Builder by entering TV in setpoint option parameter
SPOPT. If an operator is to ramp the SP, the mode attribute in MODATTR must be Oper;
and if a user-written program is to ramp the SP, the mode attribute must be Prog.

To use the SP target-value option, the operator

1. Enters the desired new SP value in SPTV.

2. Enters the ramp time (in minutes) in RAMPTIME.

NOTE
Step 1 or 2 causes the TVPROC parameter to go to Preset if the point is in the Auto mode,
INITMAN is Off, and TVPROC is Off.

3. Enters Run in TVPROC.

4. The SP begins moving linearly toward the new value and the value in RAMPTIME
decreases with time. When RAMPTIME = 0, SP reaches the new value and the status
in TVPROC changes to Off.

TVPROC can be changed to the Run state only from the Preset state. While TVPROC
contains either Preset or Run, SP high and low limits, and the SP high and low
engineering-unit ranges can't be changed.

APM Control Functions & Algorithms 8-11 12/03

 8.7.3
The following applies to TVPROC if it is in the Run state:
1. If MODE is changed to Man, state goes to Preset.
2. If MODE is changed to Cas, state goes to Off.
3. If INITMAN is true, state goes to Preset.
4. A store to SP forces the state to Off.
5. If SPTV > SP and the antireset-windup ARWNET parameter indicates that SP is
wound Hi or HiLo, the SP stops changing. When ARWNET indicates that SP is no
longer wound Hi or HiLo, SP ramping continues form the stop position. Note that
when SP is ramping, ARWNET is not shown on the Group or Detail Displays. SP
can normally be inferred from the output windup status. ARWNET can be accessed
from a custom display.
6. If SPTV < SP and the output becomes wound Lo or HiLo, the SP stops changing.
7. If none of the above is true, the SP is ramped to SPTV.

8.7.3 PV Tracking (Pid Algorithms)

PV tracking is configured by entering Track for the PVTRACK parameter. During PV
tracking, SP is set equal to PV whenever the cascade is broken by an operator or a program
action, or the RegCtl point is a secondary (in a local cascade strategy) and the cascade is
momentarily interrupted by a 1-shot initialization.
PV tracking occurs under the following conditions:
• Mode is Man.
• Mode is Cas and RCASOPT is Ddc.
• INITMAN is On, and either the mode is not Auto, or RCASOPT is not Rsp.
• RegCtl point is being processed for the first time after becoming active.
• RegCtl point is a secondary within a local cascade-control strategy (inside the same
APM), and it is going through a 1-shot control initialization. One-shot control
initialization occurs when
– the control initialization-request flag CTRLINIT is On
– the point is being processed for the first time after the APM state has changed to
Run
– just recovering from a bad PV
– this slot has only one disposable secondary that just underwent 1-shot initialization.
Note that PV tracking (even if configured) is not done on return from a Bad PV.

APM Control Functions & Algorithms 8-12 12/03

 8.7.4
8.7.4 Deviation and Advisory Deviation Alarming
8.7.4.1 Deviation Alarming (Pid, PosProp, PIDPosPr, RampSoak, and RatioCtl Algorithms)

Deviation (PV-SP) high and low alarms can be configured by using the alarm trip points
provided by the DEVHITP and DEVLOTP parameters. In addition, alarm priorities can be
established for these trip points by using the DEVHIPR and DEVLOPR parameters.
Parameters DEVHIFL and DEVLOFL are used as flags to indicate that a deviation (high or
low) alarm has been detected. This alarm returns to normal when the deviation (PV-SP) is
less than or equal to the configured trip point minus a deadband equal to 10% of the trip
point value.

8.7.4.2 Advisory Deviation Alarming (Pid, PosProp, PIDPosPr, and RatioCtl Algorithms)

This option allows an operator to manually change the SP to a predetermined value. The
predetermined value is usually calculated by a user-written program that stores the value in
advisory setpoint parameter ADVSP rather than storing it directly in SP. Advisory-
deviation alarming is selected by entering Asp for setpoint option parameter SPOPT.
This alarm type is available if the RegCtl point has been configured as a full point. When
this option is selected, an alarm is generated if the difference between the PV and the value
in ADVSP is greater than the trip-point value in ADVDEVTP. This alarm returns to
normal when the difference between the PV and ADVSP is less than or equal to the value
in ADVDEVTP minus a deadband equal to 10% of the trip-point value.
The following conditions must be true if advisory-deviation alarming is to function:
• SPOPT = Asp
• ADVDEVTP < > NaN
• ASPROC = Enable
• PV alarm status in PVVALST < > Bad
• Alarm-enable status in ALENBST < > Inhibit
If the advisory-deviation alarm is present and the value of one of the above-listed
configuration parameters is changed, the advisory-deviation alarm is reset.
If parameter ASPPROC = Disable, the value in ADVSP equals the value in SP.

8.7.5 Bad Output Alarm

The Regulatory Control point's Bad Output Alarm option (when enabled) generates a
process alarm if one or more of the configured output connections to Analog Output or
Digital Output points are broken. Broken means data cannot be pushed to a point. This
alarm is cleared when all connections to the AO or DO points are good, or when the Bad
Output Alarm Option is disabled.

APM Control Functions & Algorithms 8-13 12/03

 8.7.6

8.7.6 Ratio and Bias Options (Pid Algorithms)

NOTE
If SP target value processing or advisory deviation alarming is configured for a RegCtl point,
the ratio/bias options cannot be configured for the same data point.

The ratio and bias options are configured by entering one of the following values in ratio
and bias option parameter RBOPT:

• FixRatBi—Fixed Ratio and Bias

• AutoRat—Auto Ratio and Bias

• AutoBi—Fixed Ratio and Auto Bias

If one of these options is configured, the SP is modified before being used by the PID
algorithm as follows:

SP_Store_Value*RATIO + BIAS

Where SP_Store_Value is the setpoint before the modification.

You can configure limits for both the RATIO and the BIAS values in the following
parameters:

• RTHILM—Ratio high limit

• RTLOLM—Ratio low limit

• BSHILM—Bias high limit

• BSLOLM—Bias low limit

In normal operation (in Cas mode and INITMAN is Off), all three options work alike.
RATIO and BIAS can be changed by a Universal Station operator or by user-written
programs (depending on whether MODATTR contains Oper or Prog). During initialization
of this point, however, RATIO and BIAS can be changed only if they are not being
initialized, based on the value in RBOPT, as follows:

APM Control Functions & Algorithms 8-14 12/03

 8.7.6

• FixRatBi—The initialization value calculated for this point's primary is

RINITVAL = (SP - BIAS)/RATIO

• AutoRat—RATIO is initialized as follows:

RATIO = (SP - BIAS)/Store Value

If RATIO attempts to go outside one of its limits, it is clamped at the limit, and INITVAL
is calculated as follows:

INITVAL = (SP - BIAS)/RATIO

• AutoBi—BIAS is initialized as follows:

BIAS = SP - (Store_Value*RATIO)

If BIAS attempts to go outside one of its limits, it is clamped at the limit, and INITVAL is
calculated as follows:

INITVAL = (SP - BIAS)/RATIO

8.7.6.1 Bias Limits

Two user-setable Hi and Lo limits on the SP-related bias parameter are provided.
Whenever operator or program entries are outside the limits, the entries are clamped to the
closest limit. Crossover of limits is inhibited.

You can configure high and low limits for the BIAS value that can be applied to the
setpoint for PID algorithms. A Universal Station user with a Supervisor key can change
these limits. An operator is prohibited from entering a value exceeding these limits. A
user-written program is clamped to the exceeded limit. Crossover of these limits is
prohibited.

APM Control Functions & Algorithms 8-15 12/03

 8.7.6
8.7.6.2 Ratio Limits

You can configure high and low limits for the RATIO value that can be applied to the
setpoint for Pid Algorithms. A Universal Station user with a Supervisor key can change
these limits. An operator is not allowed to enter a value that exceeds these limits. If a user-
written program attempts to store a value outside the limits, it is clamped to the limit.
Crossover of these limits is prohibited.

8.7.7 SP Access Restrictions

The activities that can write a value to the SP are defined by Table 8-3.

8.8 SP/OP TOLERANCE CHECK

Release 530 provides a new function called “SP/OP Tolerance Check.” This functionality
has two new parameters called $SPTOL and $OPTOL that allow a SP (setpoint) and OP
(output) tolerance value to be configured by the engineer.
Manually entered SP and OP values for the AM, HG, and NIM Regulatory Control points,
OP values for HG and NIM Analog Output points, and OP values for HG Analog
Composite points are checked against this new specified tolerance. If the tolerance is
violated in either a plus or a minus direction from the current set value, the operator is
alerted with a beep from the keyboard and a warning message. Operator confirmation is
required before the value is stored.
The tolerance check is made from the Detail Display, Group Display, and in schematic
actors RS_SYS, CHG_ZONE, and USER_CZ.

8.9 ALARM DETECTION

Alarms for a RegCtl point can be configured only when the point has been configured as a
full point. The following alarm types are supported by the RegCtl points:
• PV High/Low*
• PV High-High/Low-Low*
• PV Rate-of-Change Positive/Negative*
• PV Significant Change*
• BadPV*
• Bad Control
• Deviation High/Low
• Advisory deviation
For detailed alarm information, refer to paragraph 4.3 in System Control Functions.

__________________________
* Applicable to only Pid, PosProp, and RatioCtl algorithms.

8.10

APM Control Functions & Algorithms 8-16 12/03

8.10 CONTROL OUTPUT PROCESSING

The primary task of control output processing is to make the control algorithm calculation
available to the rest of the system (displays, printers, CL programs, other data points, etc.)
in percent or EUs, as needed. Control algorithms produce outputs in percent or in
engineering units.

Control output processing performs the following functions:

• Provides the output value in percent and EUs for displays, printing, CL programs, and
for interpoint communications.

• Processes control output connections that send the output to the secondary data point
after conversion to EUs.

• Constrains the output to the configured limits.

• Generates and propagates windup status as a result of a violation an output limit.

The following parameters contain significant output-processing information. All of them

are accessible for displays and printing and all can be accessed by a program written in CL.

CV = The result (calculated value) of calculation of the control algorithm,

can be in percent or EU depending upon the control algorithm.

OP = The final control output, expressed as % of EU Range of the output.

OPEU = Final control output in Engineering Units.

CVEUHI = Output EU Range corresponding to 100% value of OP.

CVEULO = Output EU Range corresponding to 0% value of OP.

8.10.1 Initial Control Processing

During initial control processing, initialization data is fetched from the secondary points
indicated by each control output connection.

The output engineering-unit range in CVEULO and CVEUHI is determined, based on the
EU range of the secondary pointed to by the first active control output connection. If this
connection has a communication or configuration error, the output range is set to bad and
the point is aborted. If this happens, the CI connections and CO connections, scheduled for
execution after initial control processing are not processed.

APM Control Functions & Algorithms 8-17 12/03

 8.10.1

Table 8-3 — Setpoint Access Restrictions

BOX-IDLE PID ALGO. NON-PID

or ————————————————— ALGO.
MODE POINT RCASOPT PVTRK = ON PVTRK = OFF
INACTIVE —————————————————————————————
or MODE MODE MODE MODE
ATTRB ATTRB ATTRB ATTRB ATTRB
INITMAN OPR PRG
OPR PRG OPR PRG

MAN No Any I I Opr Prg* I I

Yes Any I I Opr Prg* I I

AUTO No Any Opr Prg* Opr Prg* Opr Prg*

Yes None I I Opr Prg* I I

SPC I I Opr Prg* I I
DDC I I Opr Prg* I I
DDCRSP I I Opr Prg* —— ——
RSP RC RC RC* RC* —— ——

CAS No None PC PC PC PC PC PC
SPC RC RC RC RC RC RC
DDC I I PC PC I I
DDCRSP RC RC RC RC —— ——
RSP PC PC PC PC —— ——

Yes None I I NCH NCH I I

SPC I I NCH NCH I I
DDC I I NCH NCH —— ——
DDCRSP I I NCH NCH —— ——
RSP I I NCH NCH —— ——

BCAS No Any PC PC PC PC PC PC

Yes Any I I NCH NCH I I

NOTES: I => SP is being initialized, no change permitted.

Opr => Operator from group or detail display.
Prg => Discontinuous CL programs or sequence programs.
PC => APM cascade. Mainly the output connections from another control slot in this
APM or another APM.
RC => Remote cascade. These include: continuous CL programs on LCN, output
connections from regulatory points in the AM, or user computers on the LCN.
NCH=> No change permitted.
* => Target value processor state (TVPROC) must be off

APM Control Functions & Algorithms 8-18 12/03

 8.10.2
Normal Computation

1. CV is calculated by the control algorithm.

2. OP is calculated from CV, with the units based on the range defined by CVEULO and
CVEUHI. Note that the values in CVEULO and CVEUHI are determined by the
engineering-units range of the secondary point to which the first active connection is
made.
3. OP is checked for minimum output change, output rate-of-change, output high-limit,
and output low-limit. If any of the limits is exceeded, the OP value is adjusted or
clamped as applicable.
4. The windup status is set.
5. Each control output connection is processed as follows:
If the control output connection is disposable,
The corresponding value in the secondary point is made equal to OP, if the
destination parameter is OP, otherwise it is made equal to OPEU.

The OP or OPEU value is transferred to the secondary's destination parameter,

subject to applicable limits on the destination parameter (e.g., SP limits).
In MANual Mode

1. OP is set (in percent) by an operator or by a user-written program, depending on the

attribute.
2. Each control output connection receives normal processing, as described above.
Remaining process is as defined under "Normal Computation."
When initializing because of a request from a secondary data-point

1. If all of the control output connections are indisposable, CV is initialized to its last
value. When the first disposable control output connection becomes available, the CV
is back-calculated (% to EU conversion if the destination parameter is OP) from the
destination parameter of the secondary.
2. OP is calculated from CV, based on CVEULO and CVEUHI.

8.10.2 Output High and Low Limits

You can configure high- and low-limit values for the RegCtl point output using parameters
OPHILM and OPLOLM . These limits are expressed as a percentage of the output range
and the limit values can range from -6.9% to 106.9%. A Universal Station user with a
Supervisory key can change these limits. Crossover of these limits is not permitted.
When an output limit is reached or exceeded, windup status is propagated up through
cascade strategies.

APM Control Functions & Algorithms 8-19 12/03

 8.10.3

8.10.3 Output Rate-of-Change Limits

You can configure a maximum rate of change in percent-per-minute for output values of
RegCtl points using the OPROCLM parameter. The effect of this limit is to reduce
excessive rates of change in the output, to the limit. The smallest limit can't be less than
0.1 percent per point-processing interval. The default value for the limit is NaN, which
eliminates the limit check.

Typically, the output rate-of-change limit is used to match the slew rate of the final control
element to the control dynamics.

Use caution when setting the value of OPROCLM. This value should be set before loop
tuning has taken place. When done this way, tuning accommodates any slow down in
response time caused by rate limiting. If OPROCLM is changed after a loop has been
tuned, it is possible for poor loop dynamics or even instability to result.

Note that when a choice is available, rate limiting should be applied to PID algorithms
(PID, PIDFF, and PIDERFB) rather than regulatory control algorithms of other types. The
PID algorithms support special processing to prevent windup of the CV during rate
limiting. Other algorithms cannot provide this special processing.

8.10.4 Output Minimum-Change Limit

You can configure a minimum output-change value for RegCtl points using parameter
OPMCHLM. This value is a percentage of the output-value range. If the absolute
difference between the output value at one processing pass and the next doesn't equal or
exceed the minimum change, the earlier value is maintained. A Universal Station user with
a Supervisory key can change the minimum output-change value.

The default minimum output-change value is NaN, which eliminates the minimum change
check.

This feature is used to minimize "wear and tear" on the final control device.

8.10.5 Output Limiting in Manual Mode

No output limits, output rate-of-change or output minimum-change limits are observed

while in manual mode. An indication is given to the operator if a manually entered or
program-entered output value exceeds the output limits. Output values written by CL
programs are clamped to the HI and LO output limits.

APM Control Functions & Algorithms 8-20 12/03

 8.10.6
8.10.6 Control Output Connections
Control output connections are used to establish initializable cascade connections between
the output of the RegCtl point output and other points. Control output connections are
accomplished through parameter CODSTN. To assign the RegCtl output to the parameter
of another data point, the user can choose from one of the following two output connection
conventions (Tagname.Parameter or hardware reference address):
Tagname.Parameter
or
!MTmmSss.Parameter

where: MT is the IOP type (AO or DO)

mm is the IOP number in the APM file, from 1 to 40
ss is the slot number from 1 to 8 for analog outputs, and from 1 to 16 for
digital outputs
Parameter is the parameter in the AO or DO point to which this output value is
to be written.
Up to four output connections can be configured for a RegCtl point. Initialization and
wind-up protection are supported for multioutput configurations.
The RegCtl data point can write the output value to only the following destination
parameters:
• SP, RATIO, X1, X2, X3, and X4 parameters of another RegCtl data point in the same
APM. When a control output connection is made to the RATIO parameter, the ratio
high and low limits on the secondary are used as its engineering unit range. Also the
secondary should be configured for a ratio bias option of auto ratio and placed in
Program Cascade mode for the initialization to work correctly.
• X1 parameter of a RegCtl data point in another APM or HPM on the same UCN.
• SP parameter of a RegCtl point in another APM, PM, or HPM on the same UCN.

NOTE
An output connection of this type counts as one input and one output for the purpose of limiting
the number of input/output connections going across APMs.

APM Control Functions & Algorithms 8-21 12/03

 8.10.7
• OP parameter of an analog output point in the same APM. The component form of the
output connection can be used to connect to an AO point that has been configured as a
component point. The following restrictions apply:
– The total number of control input and output connections fetching data from the
I/O Processors must not exceed seven (prefetch limit updated in R600).
– The analog output slot must be configured as a component point.
– The output destinations cannot be a mix of IOPs and RegCtl points.

• OP parameter of a digital output point that has been configured for pulse-width
modulation in the same APM. The following restrictions apply:

– The total number of control input and output connections fetching data from the
I/O Processors must not exceed seven (prefetch limit updated in R600).

• Any addressable parameter of any accessible slot if the configured control algorithm is
PidERFB.

CAUTION

Up to four output connections are permitted from a Regulatory Control point but the control
output destinations must be all IOPs (AOs or pulse width modulated DOs) or all Regulatory
Control inputs. The outputs cannot be a mix of IOPs and Regulatory Control inputs.

8.10.7 Output High/Low Alarms

With R510 and later software, an Output High or Output Low alarm is set when a
Regulatory Control point's output value (OP) exceeds the configured high or low alarm
limit. The alarm is removed when the value of OP returns toward normal past a
configurable deadband.
The following parameters deal with the Output Alarms and are configurable for each point:

OPHITP/OPLOTP contain the Output High/Low Alarm trip points

OPHIPR/OPLOPR contain the Output High/Low Alarm priorities
OPHAFL/OPLAFL contain the Output High/Low Alarm flags
OPALDB contains a deadband for the Output Alarms

The output alarms are available only for Regulatory Control points configured as full
points and are disabled if the trip points are not specified.

APM Control Functions & Algorithms 8-22 12/03

 8.11.1
8.11 INITIALIZATION
Initialization provides meaningful initial values in the data point parameters before
processing is started or restarted. Separate mechanisms are provided to initialize PV-
related parameters and control-related parameters.

8.11.1 PV Initialization
The principal purpose of PV initialization is to set up starting values the first time the point
is processed or the first time it is processed after recovering from a BadPV value status.
PV initialization is useful for only functions involved in history collection or for
dynamically varying values. Stated another way, PV initialization is required where the
new value depends on the previous value.
The following events cause PV initialization:
• Point's execution state is changed to Active.
• APM undergoes a warm or cold restart.
• PVAUTOST recovers from Bad value status.
PV initialization consists of the following functions:
• PVCALC is calculated from the PV inputs, using the steady-state portion of the
equation. For calculations that don't involve time, the normal equation is used.
• PVAUTO is made equal to PVCALC. If PV filtering is configured, the filter dynamics
are initialized to steady state.
• No other PV processing is affected by PV initialization.

8.11.2 Control Initialization

Control initialization allows normal control strategies to be re-established after they have
been interrupted without "bumps" in the output to the process, and without the need for
manual balancing of values to avoid such bumps.
Control initialization compensates for changes that may have occurred since the normal
control strategy was last operating. For example, a Universal Station operator might have
taken over control of the output to the process, so that it now has a value that is different
than normal processing would calculate. The initialization procedures automatically
readjust either the bias value in the data point(s) or an input to the data point(s) so that
when normal control is reestablished, the output to the process does not move or "bump."
For the control algorithms, the new value is back-calculated for an input that absorbs any
output change. This value and an initialization request are sent to the primary data point
that provides the input. Thus, the primary absorbs the change and it must take similar
action with its own primary, if it has one, so that the whole strategy can absorb the change.

APM Control Functions & Algorithms 8-23 12/03

 8.11.2

By configuring a control output connection from one point (primary) to an initializable

input to another point (secondary) an initialization path is created. It is along this
initialization path that a value is transferred for use by a primary to absorb external
process-upsets that may have occurred at the secondary.
Two or more active paths from a single primary to multiple secondaries are referred to as
"fan out" connections. Where there are two or more control output connections from a
primary to two or more secondaries and all of these outputs are indisposable, the primary
goes into the initialization state.

The value that is to be protected from a bump (the value to back-calculate from) is
obtained at the point's output or at the secondary's initializable input. When "fan out"
connections to more than one output are used, the Regulatory Control output is initialized
from the first disposable secondary.
General Mechanism—At each point-processing pass, the following information is
retrieved from all secondaries to which the data point has control output connections. The
data that is retrieved to support initialization is
• Initialization Request
• Initialization Value
An initialization request from the secondary causes the control output connection on the
primary to go to an "output indisposable" state, a condition where a newly generated output
to the secondary has no effect on the secondary. A control output connection also has
"output indisposable" status if an error has been detected when the initialization request
and initialization value should have been received.
When all connections from a primary are in the "output-indisposable" state, the primary is
forced to the initialized state. This causes the primary to set its initialization request. In
turn, this may cause the control output connection of a preceding primary to assume the
"output indisposable" state and may force that primary to be initialized as well. In this
manner, the initialization state is propagated upstream to all interconnected primaries.
During the initialization state, each point remains in that state until a disposable output
connection is found. For points with one control output connection, the primary sets its
output value to the initialization value received from its secondary while in the initialized
state. For points with more than one control output connection, on the first processing pass
when a disposable output connection is available, the primary sets its output value to the
initialization value received from its secondary.
When initialization is being performed for a control strategy, each data point's output is
readjusted by back-calculating an initializable input or by an internal (bias) adjustment.
When each point resumes normal calculations, the new output and the input value at its
secondary are balanced and no bump occurs.

APM Control Functions & Algorithms 8-24 12/03

 8.11.2

Indisposable outputs are not the only factor for triggering initialization. It is possible to
force a back-calculation by writing to a point's output while it is in MANual mode, or a
user program or a logic slot can set the control initialization flag in a point. For these cases,
the point does not go to the initialization state but its primary may, because the point sent
an initialization request to the primary.
Special handling is provided for connections to local I/O (e.g., Analog Outputs or Digital
Pulse Width Modulated Outputs). In the event that communication with the local output
module is lost, the mode automatically goes to MANual to permit the operator to take
control. When communication with the module is restored, back initialization to the output
value occurs automatically. The operator can then return the strategy to the desired mode.
This handling is triggered by loss of communications on the I/O link, failure of the I/O
processor, or an I/O processor-detected power outage.
Conditions that Cause Control Initialization—The need to initialize a data point is
indicated by external upsets that directly affect the point or it is indicated by an
initialization request from a secondary data point.
Control initialization is caused by any of the following:
• A user program or logic slot has requested initialization (see "Initialization Forced by a
Program," below).
• The point is active for the first time (an inactive to active transition).
• The point is executing the first time after a warm APM restart.
• All control output connections were indisposable and now one or more output
connections is disposable.
A control output connection is indisposable when
• A secondary has made an initialization request, or
• A communication/configuration error has been detected in retrieving an initialization
request and initialization value from a secondary.
The following are the reasons why a secondary data point sends an initialization request to
its primary data point:
• The secondary isn't in Cas mode, or
• The secondary is inactive.
• The initializable input to the secondary (the destination of the primary's control output
connection) is not selected for a secondary that uses the Switch algorithm (configured
for PV tracking) or the input is being bypassed by the Override Selector algorithm, or
• The secondary is in the initialization state.

APM Control Functions & Algorithms 8-25 12/03

 8.11.2

Initialization of a Point in the Same APM—For a primary and a secondary that are both
in the same APM, an enhancement is provided. This enhancement presents the operator
with an immediate indication of initialization when a cascade strategy is opened or closed.
Initialization Forced by a Program or Logic Slot—A user-written program or a logic
slot can cause a data point to initialize by setting the data point's control initialization-
request flag (CTRLINIT). The next time the point is processed, it initializes. CTRLINIT is
cleared when the processing pass is complete. An initialization request is sent to its
primary, thus propagating initialization up through the control strategy.
Limit Checking During Control Initialization—Limit checks apply during initialization
except for output rate-of-change limits.
How Initialization is Indicated at Universal Stations—When a data point that is
initializing is displayed, the display indicates that it is initializing. For example, on a group
display or a detail display, INIT appears in the point-status field that is just below the mode
indicator.

8.12 WINDUP PROTECTION

PID algorithms are protected from windup caused by reset action. Windup status
parameters are maintained that pass the status "upstream" to the primary points along the
initialization path. Each PID algorithm checks its output windup status and takes
appropriate action to prevent reset windup. These functions are standard and require no
configuration by the user.

8.12.1 Windup Status

The following parameters contain windup-status information:

• ARWOP—Output (OP) windup status

• ARWNET—Windup status for SP or another initializable input.

When this point's ARWOP contains something other than Normal, integral control in the
windup direction stops. Integral action in the other direction and P and D action continue.

For the remainder of the control subsystem, the windup status serves only as a warning,
and not as a constraint. For example if the status in ARWNET is Lo, lowering SP won't
have an immediate effect on the output of the final secondary; however, SP can be lowered
if the SP low-limit has not yet been reached.

The values in the windup-status parameters indicate whether raising or lowering the
associated parameter value will affect the output of the final secondary, as it should.

APM Control Functions & Algorithms 8-26 12/03

 8.12
The values for parameters ARWNET and ARWOP are as follows:

• Normal—Free to move in either direction

• Hi—Free to move only in the lower direction

• Lo—Free to move only in the upper direction

• HiLo—Not free to move in any direction

8.12.2 Status Propagation

Windup status is propagated to ARWOP and ARWNET of the same point, and then from
ARWNET of the secondary point to the primary point, and so on.

Propagation from secondary to primary is instantaneous if both are in the same process
unit and the same APM. Otherwise, it takes place on the next processing pass for each
point.

8.13 OVERRIDE CONTROL

Override control strategies are primarily used for multivariable constraint control. In such a
strategy, control of a single process variable is based on one of two or more PVs. These
multiple PVs are referred to as "constraints." A selector algorithm selects the PV to be
used for control. When an different PV is selected, the former PV has been overridden—
the new PV has constrained the others.
Consider the following examples:
• In typical boiler-control strategy, the constraint on the fuel flow (SP of the fuel-flow
PID controller) can be that it cannot exceed the actual air flow, multiplied by a ratio
(which may be computed by the O2 controller). In this case, the fuel flow is the primary
PV to be controlled and the actual air-flow PV is the "constraint."
• In some heating applications it may be desirable to control the temperature of the feed
(the primary PV) as well as possible, without ever letting the temperature of the hottest
part of the pot (or the heat exchanger) exceed a safe limit. In this case, the safe limit on
the pot temperature is the "constraint."
• In an oven temperature-control application, the temperatures can be measured at
several places in the oven, and it may be desirable to control all these PVs by
controlling one valve. One PID controller can be used for each PV, and the PID
controller representing the PV that is farthest from its SP can be allowed to control the
valve. In this case, there is no primary PV, because all the PVs have the same
importance. Each PID controller represents a constraint on the other PID controllers.

APM Control Functions & Algorithms 8-27 12/03

 8.13
Most often the objective is to achieve the best possible control of a PV without violating
any of the constraints. The manipulated variable is driven by the output of an Override
Selector algorithm that selects the highest or the lowest of up to four inputs. A PID that is
in a cascade strategy (but is not selected) is prevented from winding up with the help of
override initialization. In the rest of this section, the term "O/R selector" is used to mean an
Override Selector control algorithm that is configured for external initialization. Refer to
the detailed description of the Override Selector algorithm in this section.

8.13.1 O/R Status and Feedback

Regulatory data points contain the following parameters to support O/R strategies:
PTORST—This parameter contains the O/R status of the point as follows:
NotCon The point is not connected to an O/R selector. Strictly, it means that this
point is not on an initializable path to an O/R Selector or it is now being
initialized. PTORST defaults to this value.
Sel The point is a part of an O/R control strategy and is now selected
NotSel The point is part of an O/R control strategy and is not selected by the O/R
selector.

When the point is returned from inactive to active status, when it undergoes a cold start, or
when it is initialized, the status in PTORST becomes NotCon.
The following two parameters apply only to the Override Selector Control algorithm:
OROPT— When on, the feedback value is propagated to nonselected primaries of
the override selector algorithm.
When Off, the feedback value is not propagated. However, nonselected
primaries are kept from winding up by propagating a windup status
opposite of the OrSel equation (Hi-Lo) in addition to the OrSel point
windup status (ARWNET) to the nonselected primaries. This windup
status propagation prohibits the non-selected primaries of the OrSel
from winding up in the direction opposite of the OrSel selection
equation.
OROFFSET — When On, PID output is initialized to: Feedback Value + Gain * Error.
When Off, PID output is initialized to only the Feedback value.

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 8.13.2

8.13.2 Processing in an Override Control Strategy

Figure 8-3 is an example of an O/R strategy. The override portion of the strategy includes
the Override Selector point and all points "upstream" from it. Here is how O/R processing
works:
• There must be at least one PID controller in the O/R strategy. In Figure 8-3 the points
named TAG-A, TAG-B, TAG-C, TAG-D, and TAG-E constitute the O/R strategy.
• All points upstream of the O/R selector are processed on normal cycles (highest slot
index to lowest). In the example, the points can be processed in TAG-D, TAG-A,
TAG-B, TAG-C order. Their PV and control algorithms are executed normally.
• The next point to be processed is the O/R selector (TAG-E in the example). It selects
one input. Assume input X2 is selected.
• The O/R selector then propagates appropriate O/R status to each one of its own
initializing primaries. It also propagates the O/R-feedback value to the nonselected,
initializing primaries. In the example, TAG-E propagates O/R status of Sel to TAG-C
because input X2 is selected, and O/R-status Notsel to TAG-B. Further, TAG-E
propagates the O/R-feedback value to the nonselected, initializing primary, TAG-B.
TAG-D does not receive the O/R status nor the feedback value because it is not an
initializing primary.
• Each primary (provided it is in Cas mode), in turn, propagates O/R status to its own
primaries (if any). It also propagates O/R feedback upstream, if it is not selected. In the
example, TAG-B would propagate Notsel and an O/R feedback value to TAG-A.
• The propagation upstream continues until there are no more primaries. The output of
any PID in a cascade chain, connected to a nonselected input of the O/R selector is
initialized to override-feedback value, plus gain times deviation (PV-SP) if
OROFFSET is On. If OROFFSET is Off, it is initialized to the override-feedback
value. Because TAG–A contains a PID algorithm and is not selected, it undergoes O/R
initialization.

The whole cycle is repeated.

• All points downstream of the O/R selector are processed at their specified interval. In
the example, TAG-F is processed after TAG-E.

NOTE
The override status (Feedback Value) can be propagated to a maximum of five primaries.

APM Control Functions & Algorithms 8-29 12/03

 8.13.2
If there are multiple O/R selectors in a strategy

O/R-feedback propagation is initiated by only the most downstream O/R selector. In the
example, if TAG-F were also an O/R selector, the O/R strategy would consist of points
TAG-A, TAG-B, TAG-C, TAG-D, TAG-E, and TAG-F. O/R propagation would be
initiated by TAG-F and not TAG-E, as before.
Initialization in an Override Strategy

When a cascade is broken in an O/R strategy, initialization propagation supersedes O/R

propagation. In the example, if point TAG-B is placed in Man mode, it doesn't propagate
O/R status or an O/R-feedback value to TAG-A. TAG-A's O/R status then is Notcon.

TAG-A TAG-B
PV PV
OP
PID PID
OP
SP SP TAG-E
X1 O/R
TAG-C LO OP
SP SELECT
OP X2
PID
X3
PV TAG-F
To
X1
Secondary
SOME or Valve
TAG-D
CONTROL
PV ALGO.
PV ALGO. X2

Figure 8-3 — Example of an Override Control Strategy 2070

8.13.3 Guidelines for Using Override Control

You should follow these guidelines to configure properly functioning O/R strategies:
• Proportional and Derivative Action on PIDs—While PIDs in an O/R scheme can be
configured with proportional and derivative action on SP, use of these actions should
be carefully considered because undesired results may occur, such as momentary
oscillation caused by "kicks" in the error.
• Boundaries—The entire O/R strategy must be within the same APM. The number of
primaries for initiating the O/R strategy must be £ 5.
• Fanout—No fanout control output connections are allowed in an O/R strategy. All
primaries upstream from the O/R-selector point can have only one control output
connection.

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 8.14

8.14 CONTROL ALGORITHMS

8.14.1 Proportional, Integral, Derivative (PID)

8.14.1.1 Function

This algorithm operates as a 3-mode (proportional, integral, and derivative) controller.

You can choose one of two forms of this algorithm: the interactive (or real) form and the
noninteractive (or ideal) form.

The output of this algorithm is normally "floating," because of the dynamics of the integral
and derivative terms. Internally, the output is calculated as increments of output change,
but the increments are accumulated to provide a full-value output, thus simplifying the
techniques used to achieve "bumpless" outputs when modes or tuning constants are
changed.

The algorithm operates to reduce error in the control loop to zero. Error is represented by
the difference between the process variable in percent (PVP) and the setpoint in percent
(SPP). The control-algorithm output value (CV) is also calculated as a percentage of the
configured engineering-units range for the data point that uses this algorithm.

8.14.1.2 Use

The PID algorithm is used as a controller that either directly moves a control device
(valve) in the process, or provides an input to another data point.
This algorithm requires only one input connection. The default for number of input
connections is 1; however, it can be increased to 2, allowing the SP to be fetched with an
input connection. When the SP is fetched, the normal operating mode of the point is
usually affected.
When the APM's PID point is a primary for another data point in the same APM or
another APM (or PM) on the same UCN, its output is connected to the SP of the other data
point (via Tagname.Parameter). If the APM's PID point is directly controlling a valve, its
output is connected to the output of a Analog or Digital IOP (through
"Tagname.Parameter" or the hardware reference address !AOmmSss.OP or
!DOmmSss.OP where mm is the IOP card number in the APM, and ss is the slot number
of the output on the IOP card).
If the APM point is a secondary for another data point, it can be configured to receive an
input from another source. Sources include another data point on the same UCN, an AM
data point, or a point properly configured in another CM with proper access level. If the
remote cascade connection is coming from a regulatory data point in the AM, it handles
everything automatically.

APM Control Functions & Algorithms 8-31 12/03

 8.14.1

Setpoint
From Initializing Processing
Primary
CAS
SPP
To
PID CV OP Secondary
AUTO
Operator or PVP
User-Written
Program Output
From PV Algo
Processing
or IOP

PID Forms: Interactive (Real)

Noninteractive (Ideal)

Equations:
A: Full PID
B: PI on error, D on PV change only
C: I on error, PD on PV change only 1327
D: Integral control only

Feedforward Action: Additive, Scale and Add

Multiplicative; Scale and Multiply

Figure 8-4 — Functional Diagram, PID Control Algorithm 1327

In all other cases (including the continuous CL programs in the AM directly writing to the
APM), the user must explicitly take care to assure

• The remote device must use "continuous_control" access level for stores to SP, OP,
and MODE parameters.

• It must also handle mode changes for closing the cascade. See 8.4.4, Remote Cascade
Requests, for additional information.

• Initialization for bumpless mode transfers.

• Windup protection.

This algorithm supports all remote cascade options. PV source selection is supported if
the point is configured "full." See 7.5, PV Source Selection, for details.

For additional information on restrictions on types and numbers of control output

connections, see 8.10.6, Control Output Processing.

APM Control Functions & Algorithms 8-32 12/03

 8.14.1

8.14.1.3 Options and Special Features

8.14.1.3.1 Interactive and Noninteractive PID Forms

During configuration, select one of these two forms. They differ as follows:

• Interactive (Real) Form—This form emulates traditional pneumatic-PID controllers.

The P, I, and D terms are calculated as the sum of P and I, multiplied by D. D interacts
in the time domain with the P and I terms. An advantage of this form is that the poles
(lags) and zeros (leads) can be easily placed (see the equations under 8.14.1.4). The
poles and zeros must be real.

• Noninteractive (Ideal) Form—In this form, P, I, and D are added in the time domain.
D is added as a damped derivative to limit peak amplitude. This form is often called
the digital-computer version of the PID controller.

8.14.1.3.2 Engineering Unit Ranges

The PV engineering unit range (PVEULO and PVEUHI) must be specified. The setpoint
engineering unit range (SPEULO and SPEUHI) always follows the PV range. The output
engineering unit range (CVEULO and CVEUHI) is derived from the secondary if the
number of output connections is greater than 0, otherwise it must be specified.

8.14.1.3.3 Four Combinations of Control Terms

You select the combinations of proportion, integral, and derivative control terms by
choosing Equation A, B, C, or D. The equations function as follows (also see 8.14.1.4):

• Equation A—all three terms (P, I, and D) act on the error (PV - SP).

• Equation B—The proportional and integral terms act on error (PV - SP) and the
derivative acts on PV changes. This equation is used to eliminate derivative spikes in
control action that occur with quick changes in the setpoint.

• Equation C—The integral term acts on error (PV - SP) and the proportion and
derivative terms act on PV changes. This equation provides the smoothest and slowest
response to setpoint changes.

• Equation D—This equation provides only integral control.

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 8.14.1
8.14.1.3.4 Control By a Single Term

When you use equation A, B, or C, the integral or derivative terms can be eliminated by
setting their time constants to 0 (see 8.14.1.4). Setting both T1 and T2 to 0 results in only
proportional control.

Use Equation D to achieve only integral control.

8.14.1.3.5 Direct and Reverse Control Action

When configuring a data point that uses the PID algorithm, you can select direct-control
action or reverse-control action. You can also change the control action through the detail
display if you have an engineer's key, or a user-written program can change the control
action. The control action can be changed at the Universal Station or by a program, only
while the data point is in Man mode. The attribute must be appropriate (Oper or Prog) for
the change to be accepted.

Changing the control action effectively changes the sign of the gain. With direct action, an
increase in PV increases output; with reverse action, an increase in PV decreases output.
As an example, with direct-control action, assume
SPP = 50%
PVP = 51%
Deviation = PVP - SPP = 1%
If PVP increases, the deviation (error) increases, so the output, CV, increases (see
Equation A under 8.14.1.4).
The opposite occurs with reverse-control action: If the deviation increases, CV decreases.

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 8.14.1

8.14.1.3.6 PV Tracking

PV tracking is configured by setting PVTRACK to Track. If configured, SP is set equal to

PV when the cascade is broken by an operator, a program action, or when this data point is
a secondary in a local cascade strategy and the cascade is momentarily interrupted by one-
shot initialization; that is, when the following conditions exist

• The data point that uses this algorithm is in Man mode.

• The mode of this data point is Cas and RCASOPT = Ddc

• INITMAN = On, and either the mode is not Auto, or RCASOPT is not Rsp

• The first time the data point is processed after becoming active.

• This slot is a secondary within a local (inside the same APM) and is going through 1-
shot control initialization.

NOTE
The 1-shot control initialization occurs when

• the control initialization request flag (CTRLINIT) is On

• this slot is being processed for the first time after the APM state has changed to
RUN (OK)
• this slot has just recovered from a bad PV
• this slot has only one disposable secondary that just underwent 1-shot
initialization

PV tracking is typically chosen when the data point is a secondary in a cascade control
strategy, because it allows the PID to resume control with no error, after the point has been
in Man mode or is initialized.

PV tracking can also be used when the data point is the ultimate primary point. In such a
case, a startup procedure could be used where the point is started in Man mode and the
valve manually adjusted to bring the PV close to the desired value, and the data point
would then be switched to Auto.

PV tracking (even if configured) is not done on return from a Bad PV.

APM Control Functions & Algorithms 8-35 12/03

 8.14.1

8.14.1.3.7 Gain Options

When configuring a data point that uses the PID algorithm, and equations A, B, or C, you
can choose any of the following four gain options:

• Linear Gain—This is the most commonly used gain option. The gain, K, used in the
chosen equation (see 8.14.1.4) is set by the user. The default value for K is 1.

• Gap Gain Modification—This option is used to reduce the sensitivity of the control
action when the PV is in a narrow band (gap) around the setpoint. The size of this
band is specified by the user. K, as used in the chosen equation is derived as follows:

K = KLIN * KGAP, if (SP - GAPLO) < PV < (SP + GAPHI)

or,

K = KLIN, if PV is outside the gap.

Where:

KLIN = A linear-gain parameter, in percent-per-percent. The range of

KLIN is 0.0 to 240.0, and the value is tuned at a Universal
Station. Default = 1.0
KGAP = Gain-modification factor, specified by the user. The range of
KGAP is 0.0 to 1.0. Default = 1.0.
GAPLO = The bottom limit of the gap in the same engineering units as
the PV. GAPLO can be any value ≥ 0.0. Default = 0.
GAPHI = The upper limit of the gap in the same engineering units as the
PV. GAPHI can be any value ≥ 0.0. Default = 0.

• Nonlinear Gain Modification—This option provides control action proportional to the

square of the error, rather than the error itself. The gain, K, used by the chosen
equation, is derived as follows:

K = KLIN * KNL

NLGAIN * (|PVP - SPP|)

KNL = NLFM + 100

If the resulting value in K exceeds 240.0, it is clamped at 240.0.

Where:

KLIN = Same as for gap gain

KNL = Nonlinear-gain modifier
NLFM = Nonlinear-gain form. 0 or 1, as specified by the user.
Default = 1.

APM Control Functions & Algorithms 8-36 12/03

 8.14.1

For the ideal form of the PID, nonlinear gain does not act on the derivative component.

NLGAIN = Nonlinear gain, specified by the user. Value ranges from 0.0 to
240.0. Default = 0.
PVP = PV in percent
SPP = SP in percent

• External Gain Modification—The gain, K, used by the chosen equation, is modified by

an input value that can be from the process, from a PV calculated from a process input
by a PV algorithm, or from a user-written program.

The main use of this option is to compensate for nonlinear-process gain. The user can
tune the PID gain independently of the operating point of the process. For example, in
controlling the level in a tank whose cross section is not constant, the gain could be
modified to compensate for the nonlinear rate of level change that is caused by the
changing shape of the tank. The General Linearization PV algorithm (subsection
7.9.8) could be used to compute the inverse of the level-change characteristic, and the
resulting PV could be used to modify the level-control gain.

K is derived as follows:

K = KLIN * KEXT

If the resulting value in K exceeds 240.0, it is clamped at 240.0.

Where:

KLIN = Same as for linear gain

KEXT = The external gain-modification factor. It can be entered by a
user-written program, or it can be a general input from another
data point. KEXT must be a positive number. Default = 1.0.

It is possible to use this option for multiplicative-feedforward control, but the PID with
Feedforward-control algorithm (subsection 8.14.2) is a better choice because it
provides a better operator interface and better recovery from a "bad" feedforward
input.

8.14.1.3.8 Windup Handling

When the output of this algorithm reaches the user-specified output limits, or reaches the
setpoint limits of the data point's secondary, or when a woundup-status indication is
received from the secondary, the PID algorithm stops calculating the integral term but the
calculation of the proportional and derivative terms continues.

This is the same way that windup conditions are handled in Basic Controllers,
Multifunction Controllers, and Extended Controllers.

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 8.14.1

8.14.1.3.9 Suppression of Output "Kicks" When Switching to Cas Mode

Without this suppression feature, the first setpoint change after switching from Man or
Auto to Cas mode could cause a sudden move (kick) in the output because of the
proportional or derivative terms. This "kick" occurs when, for some reason, the primary
data point's output is not initialized, and an abrupt change in the setpoint occurs when Cas
mode resumes.

To suppress this "kick," the proportional and derivative terms are not calculated the first
time the PID data point is processed after changing to Cas mode.

This feature is especially useful when the PID point is one of two or more secondaries of
its primary data point. When this data point is changed to Cas mode, even if the primary is
not initialized, the output of this data point does not bump the first time it is processed.

8.14.1.3.10 Initializing PID Output Without Affecting Dynamics

A logic slot or a user-written program in the APM, AM, or a CM (FORTRAN or Pascal)

can store a value in the CV parameter of the PID data point, even while the algorithm is
doing its normal, incremental PID calculation. This may change the full-value output of
the data point, but it has no effect on the continuing incrementation or decrementation of
the output. It is possible, therefore, for a user-written program to initialize a PID output
without affecting the dynamics of the PID calculations, and without initializing the output
of the primary data point.

As an example of the usefulness of this feature, consider a single PID that is controlling
temperature by controlling the flow of either gas or oil. This PID's output is connected to
both flow controllers, but only one secondary is in cascade at any time. When a change
from one fuel to the other is made, the user-written program initializes the output of the
temperature-controller PID by storing a new, full-value output in CV. The cascade
connection is switched from one to the other, and the dynamic compensation of the flow of
the new fuel proceeds. The value stored in CV is the setpoint of the new secondary in
percent (SPP). Through this technique, the full-value output of the primary has been
initialized without affecting its dynamic calculations, so the fuel switchover is quick and
smooth.

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 8.14.1

8.14.1.3.11 Restrictions on Some Values

The following are restrictions on some of the values used with this algorithm:

• The engineering units range that you specify for the PV also applies to the SP.

• For best performance, we recommend that the integral (T1) and derivative (T2) time
constants be within the following ranges:

T1 > 20.0 * TS

T2 > 100.0 * TS for the interactive form of the PID, and

T2 > 10.0 * TS for the noninteractive (ideal) form of the PID

Where TS = the interval at which the data point is processed, in minutes.

For the interactive form of the PID,

If T1 > 0 but < 2.0 * TS, it is clamped to 2.0 * TS

If T2 > 0.but < 10.0 * TS, it is clamped at 0.0

8.14.1.3.12 Bias Options

Ratio control can be achieved by modifying the setpoint input to the PID algorithm by a
RATIO of some other process point that is stored to through a control output connection,
for example, a fuel-to-air ratio in furnace control (it can also be accomplished with the
Ratio Control algorithm. See 8.14.6). When configuring a PID data point, you can select
one of the following options for modifying the setpoint through the RBOPT parameter:

• No ratio or bias

• Fixed ratio and bias

• Auto ratio (fixed bias)

• Auto bias (fixed ratio)

If you select one of the ratio and bias options, configured or operator-entered ratio and bias
values are used to modify the setpoint (by multiplying it by the ratio and adding the bias
value) only while the data point is in Cas mode. In Auto mode, the ratio calculation does
not occur because this option is intended to receive the process value to be modified by the
ratio, only from another data point (which can happen only in the Cas mode).

APM Control Functions & Algorithms 8-39 12/03

 8.14.1
The "Auto ratio and Auto bias" options adjust the ratio or bias while the data point is in
Auto or Man modes, or is undergoing initialization, so that when it returns to Cas mode,
the new SP won't "bump" the process. The adjustment is as follows:
• For Auto ratio, the operator can change only bias, and ratio is calculated to maintain
the same setpoint when the mode is changed to Cas. The operator can change the ratio
in Cas mode.
• For Auto bias, the operator can change only ratio, and bias is calculated to maintain the
same setpoint when the mode is changed to Cas. The operator can change the bias in
Cas mode.
Modification of the setpoint by a ratio and a bias is actually handled by setpoint processing
rather than by the PID algorithm. It is applied to only PID setpoints.
These options allow this one algorithm to perform PID Ratio, PID Auto Ratio, and PID
Auto Bias functions.
The parameters used for these options are RBOPT, RATIO, BIAS, RTHILM, RTLOLM,
BSHILM, and BSLOLM.

8.14.1.3.13 Operating Modes

The PID algorithm operates in the following modes:

• Man
• Auto
• Cas
• Bcas — If RCASOPT = Spc or Ddc or DdcRsp

8.14.1.3.14 Remote Cascade Options

All Remote Cascade Options are supported: Spc, Ddc, DdcRsp and Rsp.

8.14.1.3.15 Restart or Point Activation

On a warm restart, or when the data point is activated, initialization takes place as
described under 8.14.1.5.

8.14.1.3.16 Error Handling

If the status of the PV value goes bad, the CV value is changed to bad (NaN) and the data
point remains in the current mode. When the PV-value status returns to normal, the CV
value is initialized and the PID dynamics are returned to a steady state. An initialization
request and initialization value are sent to the primary data point.

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 8.14.1

8.14.1.4 Equations

You can select one of four equations when you configure a data point that uses the PID
control algorithm. Equations A through D differ in the interactive and noninteractive
forms of the algorithm.

For the Interactive form:

Equation A — P, I, and D act on the error

1 + T1 * s 1 + T2 * s
CVs = K * [ T1 * s * 1 + a * T2 * s * (PVPs - SPPs)]

Equation B — P and I act on error, D acts on PV

1 + T1 * s 1 + T2 * s 1 + T1 * s
CVs = K * [ T1 * s * 1 + a * T2 * s * PVPs - T1 * s *
SPPs]

Equation C — I acts on error, P and D act on PV

1 + T1 * s 1 + T2 * s 1
CVs = K * [ T1 * s * 1 + a * T2 * s * PVPs - T1 * s * SPPs]

Equation D — Integral control, only

1
CVs = T1 * (PVPs - SPPs)
* s

For the Noninteractive form:

Equation A — P, I, and D act on the error

1 + T1 * s
CVs = K * [( T1 * s + T2 * s) * (PVPs - SPPs)]

Equation B — P and I act on error, D acts on PV

1 + T1 * s 1 + T1 * s
CVs = K * [( T1 * s + T2 * s) * PVPs - T1 * s * SPPs)]

Equation C — I acts on error, P and D act on PV

1 + T1 * s 1
CVs = K * [( T1 * s + T2 * s) * PVPs - T1 * SPPs]
* s

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 8.14.1
Equation D — Integral control, only

1
CVs = T1 * (PVPs - SPPs)
* s

Where:

CV = Output of the PID algorithm, full value in percent

a = A constant equal to 0.1. 1/a is the high-frequency gain or rate

amplitude.

K = Gain. See 8.14.1.3.7.

PVP = The process variable in percent

s = The Laplace operator

SPP = The setpoint in percent

T1 = The integral time constant in minutes per repeat for interactive

form. See 8.14.1.3.11, Restrictions on and Recommendations
for Some Values.

T2 = The derivative time constant in minutes. See 8.14.1.3.11,

Restrictions on and Recommendations for Some Values.

8.14.1.5 Initialization

When the output destination of the primary is to the secondary, initialization occurs as
follows:

• When the control initialization request flag (CTRLINIT) is on

• When this slot is being processed for the first time after the APM state (APMMSTS)
has changed to Run or OK

• When this slot is just recovering from a Bad PV

• When this slot has only one disposable secondary that just underwent 1-shot
initialization

• When the output is indisposable (when the mode of the secondary slot is not in Cas)

APM Control Functions & Algorithms 8-42 12/03

 8.14.1
8.14.1.6 Override Feedback Processing

When a PID point's secondary uses an Override Selector algorithm (see Figure 8.5), the
following functions take place:
• When override feedback is propagated, override status is returned in PTORST to the
PID point. The status is one of these.
Not Connected
Selected
Not Selected
• When the PID point is processed, it does the following.
If the status returned is Not Connected, there is no action.
If the status returned is Not Selected and if the PID point's mode is Auto or Cas and
CV is not equal to NaN, the PID point's CV is initialized as follows:
IF OROFFSET = On, CV = ORFBSEC* + GAIN * ERROR
CV = ORFBSEC + K * (PVP – SPP)

where K * (PVP - SPP) = offset value if the direct-control option is chosen, or

CV = ORFBSEC – K * (PVP – SPP)

if the reverse-control option is chosen.

IF OROFFSET = Off
CV = ORFBSEC

where ORFBSEC is the override-feedback value (in %) sent to the PID from the
secondary.
When the PID point is not selected, if it is in Cas mode an override-feedback value is
calculated as follows and sent to the primary:
If RBOPT is not equal to NoRatBi
PV - BIAS
ORFB = RATIO

otherwise, ORFB = PV
Note that if equation D is selected, K = 1 in these equations.

*ORFBSEC is not an external parameter

APM Control Functions & Algorithms 8-43 12/03

 8.14.1
The not connected/not selected/selected status received from the PID's secondary, is
also sent on to the primary.

NOTE
If the offset value is in such a direction that it causes the nonselected PID to become selected,
the offset values will be set to 0.0.

See 8.13, Override Control, for more information on override control.

8.14.1.7 PID Parameters

In addition to the parameters already mentioned, the following parameters are associated
with the PID algorithm (refer to the Advanced Process Manager Parameter Reference
Dictionary):
CTLEQN PVTRACK DEV DELCV

Deviation (DEV) and incremental output (DELCV) are accessible parameters.

8.14.1.8 Control Output Connections

Control outputs can be to the following destinations:

• SP, RATIO, X1, X2, X3, and X4 parameters of another control slot in the same APM
box.*
When output connections are made to RATIO, the secondary mode should be Cas and
MODATTR should be PROGRAM and RBOPT should be AutoRat.
• SP of a control slot in another APM (or HPM or PM) box on the same Universal
Control Network.*
• X1 input of a control slot in another APM (or HPM) box on the same UCN.
Note that such a connection counts as one output and one input for the purpose of
limiting the number of UCN connections.
When output connections are not to any of the above, they can be to
• OP parameter of an analog output slot inside an AO IOP in the same APM box*. AO
point must be configured as a component point.
• OP parameter of a digital output slot (configured for DOTYPE = PWM ) in the same
APM box.*
• Any addressable parameter of any accessible slot if the control algorithm is PID with
external reset feedback.
Output does not go to a device on the Data Hiway (MC, EC, CB).

* See 8.10.6, Control Output Connections, for restrictions and additional information.

APM Control Functions & Algorithms 8-44 12/03

 8.14.2

From
Primary
CAS
SPP PID
CV OP X1 CV
AUTO X2 Override
X3 SELECTOR
X4

INITVAL
To PTORST PTORST
Primary
ORFBSEC ORFBSEC

ORFBSEC is not an external parameter

Figure 8-5 — Override Feedback Processing 1329

8.14.2 PID with Feedforward (PIDFF)

8.14.2.1 Function

This algorithm operates as a 3-mode (proportional, integral, and derivative) controller. It

is identical to the PID algorithm (8.14.1), except that it accepts a feedforward signal to be
added to, or multiplied by, the algorithm's incremental output, before the full-value output
is accumulated. This algorithm lets you combine a feedforward signal with the PID output
without using another data point or algorithm to do it.
8.14.2.2 Use

The use of the PID Feedforward Control algorithm is the same as the PID algorithm,
except that this algorithm can accept a dynamic feedforward signal from the process, or a
value that is representative of some condition in the process, to be combined with the
PID's incremental output before the full-value output is accumulated.

This algorithm requires two input connections (from PV processing and FF inputs). The
inputs can be increased to three, allowing the SP to be fetched with an input connection.
The feedforward signal can be obtained from an analog-input point, and it is often
subjected to dead-time compensation or lead-lag compensation before being connected to
the FF input of this algorithm. That compensation can be provided by algorithms such as
the Variable Dead-Time with Lead-Lag Compensation PV algorithm (7.7.6). Figure 8-7
shows an example of such a strategy.
If additive-feedforward action is chosen, the feedforward signal is multiplied by a user-
specified scale factor (KF) and added to the incremental output of the PID computation.
This scale factor might be used to convert an engineering-units input to a percentage.

APM Control Functions & Algorithms 8-45 12/03

 8.14.2
If multiplicative feedforward action is chosen, the feedforward signal is multiplied by the
scale factor (KF) and then multiplied by the full value output of the PID computation.
This action is typically used to compensate for variations in process gain that are caused
by changes in throughput. For example, if the feed rate is doubled in a heating application,
twice the amount of fuel might be required, which is the equivalent to doubling the
process gain.

This algorithm supports all remote cascade options and PV source selection (if the point is
configured as a full point).
8.14.2.3 Options and Special Features

All of the following PID Control-algorithm options and special features apply to the PID
Feedforward Algorithm:

• 8.14.1.3.1 Interactive and Noninteractive PID Forms

• 8.14.1.3.2 Engineering Unit Ranges

• 8.14.1.3.3 Four Combinations of Control Terms

• 8.14.1.3.4 Control By a Single Term

• 8.14.1.3.5 Direct and Reverse Control Action

• 8.14.1.3.6 PV Tracking

• 8.14.1.3.7 Gain Options

• 8.14.1.3.8 Windup Handling

• 8.14.1.3.9 Suppression of Output "Kicks" when Switching to Cas Mode

• 8.14.1.3.10 Initializing PID Output Without Affecting Dynamics, except where

multiplication of the feedforward signal is configured

• 8.14.1.3.11 Restrictions on Some Values

• 8.14.1.3.12 Ratio Control

• 8.14.1.3.13 Operating Modes; Man, Auto, and Cas

• 8.14.1.3.14 Remote Cascade Options

• 8.14.1.3.15 Restart or Point Activation

• 8.14.1.3.16 Error Handling

APM Control Functions & Algorithms 8-46 12/03

 8.14.2

Setpoint Feedforward
From Initializing Processing Signal
Primary
CAS
SPP
To
PIDFF CV OP
AUTO Secondary
PVP
Operator or
User-Written
Program Output
From PV Algo or
I/O Module Processing

PID Forms: Interactive (Real)

Noninteractive (Ideal)
Equations:
A: Full PID
B: PI on error, D on PV change only
C: I on error, PD on PV change only
D: Integral control only

Feedforward Action: Additive, Scale and Add

Multiplicative; Scale and Multiply

1330

Figure 8-6 — Functional Diagram, PID Feedforward Control Algorithm

Inlet Feed

Dynamic Feed-Forward
PV Algorithm:
Signal
F Variable Dead-Time
with Lead-Lag

PIDFF % Fuel Flow

Auto Controller
SPP Output
PID +, * OP
Cas Accumulation
PVP

T Fuel

Outlet Feed
1331
Figure 8-7 — Example, PIDFF Control Algorithm in Feed Heater Control

APM Control Functions & Algorithms 8-47 12/03

 8.14.2

8.14.2.3.1 Add or Multiply Action

Parameter FFOPT is configured to specify whether the feedforward signal is to be added to

the incremental PID output or multiplied by it.

8.14.2.3.2 Bypassing Feedforward Control Action

An operator at a Universal Station or a user-written program can bypass the feedforward

action by one of the following:

• If the feedforward signal comes from a PV algorithm, switch the PV source for the
data point that is using the PV algorithm to Man (if you do this and the PV is changed
while the PVSOURCE is Man, the feedforward signal is affected). To resume
feedforward action, switch the PVSOURCE back to Auto.

• If the feedforward signal comes from a control algorithm, switch the mode of the data
point that is using the control algorithm to Man (if you do this and the output (OP) is
changed while the source point is in manual, the feedforward signal is affected). To
resume feedforward action, switch back to Normal mode (Auto or Cas).

8.14.2.3.3 Feedforward Signal Value Status

If the value status for the feedforward signal goes bad, the feedforward component of the
output value is frozen at the last good value and normal PID processing continues.

When the value status of the feedforward signal returns to normal, normal feedforward
action resumes. This does not cause a bump in the output because any change from the
last good value is internally absorbed and the PID dynamics are not affected. The floating,
full-value output continues as if there were no feedforward change, but the contribution of
the feedforward action continues from that time.

8.14.2.3.4 Operating Modes

The PIDFF algorithm operates in the following modes:

• Man

• Auto

• Cas

• Bcas — If RCASOPT = Spc or Ddc or DdcRsp

8.14.2.3.5 Remote Cascade Options

All Remote Cascade Options are supported: Spc, Ddc, DdcRsp and Rsp.

APM Control Functions & Algorithms 8-48 12/03

 8.14.2
8.14.2.4 Equations

You can select PID equations, just as described for the interactive form and the non-
interactive form under 8.14.1.4.
In addition, the feedforward signal is applied to the incremental output of the PID
computation, as follows:
• If additive action is configured
CVn = CVn-1 + DELCV + KFF * (FFn - FFn-1)

DELCV = Incremental output

If the status of FFn or FFn-1 is Bad,

CVn = CVn-1 + DELCV.

• If multiplicative action is configured

CVPID = CVPID + DELCV
CV = CVPID * (KFF * FFn + BFF)

When multiplicative action is configured, CV is a read-only parameter for CL

programs.
If the status of FFn is Bad,
CV = CVPID * (KFF * FF lgv + BFF),

where FF lgv = last good value of FF.

If FFn is OK but the status of FFn-1 is bad,
CV
CVPID = (KFF
* FFn + BFF)

Note that the back calculation of CVPID keeps CV unchanged, and thus, prevents a
bump.
If the result of (KFF * FFn + BFF) is less than 0.01, it is clamped at 0.01.

Where:
CV = Full-value output in percent, PID combined with feedforward
action
CVPID = The full value output before the multiplicative term. This is an
internal parameter and is not available to displays nor to user-
written programs.
DELCV = The incremental output of PID computation. Default = N/A.
BFF = Bias value for multiplicative action. Default = 0.

APM Control Functions & Algorithms 8-49 12/03

 8.14.2
FF = The feedforward input signal, from a control-input connection.
Normally from a parameter with a percentage value. Default =
N/A
FF lgv = Last good value for the FF input (notation only, not a user-
visible parameter).
KFF = Scale factor applied to FF. Normally the source parameter is in
units of percent. However, if it isn't, KFF can be used as an EU
to percent conversion factor. In this case, KFF is set to:
100
EUHI - EULO

Where EUHI and EULO correspond to the EU range of the

source parameter.
n and n-1 = Notation to indicate the value this pass (n) and the preceding
pass (n-1).
8.14.2.5 Initialization

Initialization is as described under 8.14.1.5.

8.14.2.6 Override Feedback Processing

Override-feedback processing is the same as described under 8.14.1.6, except that, if

multiplicative action is configured, a feedforward term is added to the output calculation,
as follows:
If the status returned is not selected and if the PID point's mode is Auto or Cas and CV is
not equal to NaN, the PID point's CV is initialized as follows:
If OROFFSET = On
CV = ORFBSEC + K * (KFF * FF + BFF) * (PVP - SPP)

if the direct-control option is chosen, or

CV = ORFBSEC - K * (KFF * FF + BFF) * (PVP - SPP)

if the reverse-control option is chosen.

ORFBSEC* is the override-feedback value from the secondary in percent
If OROFFSET = Off
CV = ORFBSEC + (KFF * FF + BFF)
If direct-control option is chosen, or
CV = ORFBSEC - (KFF * FF + BFF)
if reverse-control option is configured.

*ORFBSEC is not an external parameter

APM Control Functions & Algorithms 8-50 12/03

 8.14.3
8.14.3 PID with External Reset-Feedback (PIDERFB)
8.14.3.1 Function

This algorithm operates as a 3-mode (proportional, integral, and derivative) controller. It

is identical to the PID algorithm (8.14.1), except that it accepts a reset feedback signal to
be combined with this algorithm's incremental output, before the full-value output is
accumulated. It also accepts a tracking-value signal.
The intent of this algorithm is to prevent windup when it has a secondary data point,
typically a PID point, that may or may not be responding to the output of this data point.

Setpoint
Processing

CAS
To
SPP PIDERFB CV OP Secondary
AUTO
PVP
Operator or
User-Written
From PV Algo
Program
or IOP
S1 Tracking Switch Control
TRFB Tracking Value*
RFB Reset Feedback Value**

* Typically PV or SP of Secondary PID

PID Forms: Interactive (Real) ** Typically PV of Secondary PID

Noninteractive (Ideal)

Equations: A: Full PID

B: PI on error, D on PV change only
C: I on error, PD on PV change only
D: Integral control only

Reset Feedback Action: Scaled, integrated CV - RFB deviation is added

to incremental PID output before full-value output
accumulation.

4250

4250
Figure 8-8 — Functional Diagram, PID with External Feedback Control Algorithm

APM Control Functions & Algorithms 8-51 12/03

 8.14.3

8.14.3.2 Uses

The use of the PID with External Reset-Feedback algorithm is the same as the PID
algorithm, except that this algorithm can accept a reset-feedback signal (RFB) from
another data point, typically the PV of the secondary PID data point that is receiving its
setpoint from this data point.

This algorithm requires three input connections:

• From PV Processing (PVAUTO)

• RFB (Reset Feedback Value) — typically from the PV of another data point which is
receiving its setpoint from this data point

• TRFB (Tracking Value) — typically the PV or SP of another data point that is

receiving its setpoint from this data point.

Output destination can be to a secondary data point in the APM or to any desired
destination using control output connection (that is, any addressable parameter of any
accessible slot).

The number of inputs can be increased to four, allowing the SP to be fetched with an input
connection.

The tracking switch-control signal (S1) is usually stored with an output connection from a
Logic slot (or a program). If the switch control is On, the CV value from this data point is
replaced by the tracking value. If, for some reason, the secondary is not using the output
of this data point, S1 can be set to On by logic external to the PIDErfb, which causes this
point's CV to track the secondary's PV. When the secondary begins to accept OP from this
point for control, S1 is set to Off (by the external logic), and CV is then at the same value
as the controlled variable (PV), so there is no bump and normal control can resume.

In a simple application, both the reset-feedback signal and the tracking value may come
from the PV of the secondary data-point. See Figure 8-9.

APM Control Functions & Algorithms 8-52 12/03

 8.14.3

PIDERFB
SPP OFF
PID +/- Output
PVP Accum CV OP SP PID
S1
On PV

Scaling and TRFB

Integration RFB

1333
Figure 8-9 — Example of Application for PIDERFB

8.14.3.2.1 Use of Hand/Auto Stations

The following functions will be supported by the APM to integrate a third-party hand/auto
station:

• OUTPUT Ability to manipulate the output of the hand/auto station (when in Auto
position) from the PID, and to initialize the PID output to allow the
hand/auto station to switch bumplessly to auto position.

• MODE Indication that the hand/auto station is in "hand" (or Local Manual)
position at the group display of the PID driving the output.

• PV and SP Indication of PV and SP at the hand/auto station, and optionally the

ability to raise or lower the PID SP from the hand/auto station. PV and
SP may be from the PID driving the output, or from a different PID. For
example, in a single loop case, the PV, SP and output all come from the
same PID, but in case of a temperature flow cascade, the PV and SP come
from the temperature controller, and the output is driven by the flow
controller.

In order for the interface to be generic (to allow support for hand/auto stations from many
different vendors), all signals are wired into the APM through analog and digital IOPs.
This requires a total of two AI slots, one AO slot, and two DI slots in addition to the
requirements if no hand/auto station support is desired.

APM Control Functions & Algorithms 8-53 12/03

 8.14.3

8.14.3.2.2 Interface Requirements for Hand/Auto Station

The following I/O signals must be supported by the third-party hand/auto station:

• PV_IN: Analog input used to display the PV value on the hand/auto station. The
signal from the analog transmitter is wired into this input as well as to the
APM through an AI IOP.

• CV_IN: Analog input from the controller. It represents the control value position
requested by the APM's PID.

• CV_OUT Analog output. This output drives the control valve. When the hand/auto
station is in auto position, CV_OUT should track the CV_IN input; when
in local manual position, it can be manipulated by the raise/lower keys.

This output is also fed back to the APM through an AI IOP for
initialization of the PID output. The corresponding AI FTA must not be
grounded (the zero-ohm resistor to ground at the FTA should be
removed). Also the output current drive capability of the hand/auto
station must be sufficient to handle an additional 250 ohm resistor used to
convert 4-20 milliamps to 1-5 volts.

• MAN_STS: Digital output indicating that the hand/auto station is in local manual
position.

• SP_IN: Analog input used to display the SP value on the hand/auto station. The
setpoint of the APM's PID controller is connected to this input through an
AO IOP.

NOTE: This is not required if SP raise/lower capability is not to be

supported.

• SP_OUT: Analog output generated by the hand/auto station to change the SP value
of the APM's SP.

• SP_CHNG: Digital output requesting the APM to accept a new SP (equal to

SP_OUT) from the hand/auto station.

NOTE: This is not required if SP raise/lower capability is not supported.

APM Control Functions & Algorithms 8-54 12/03

 8.14.3

8.14.3.3 Options and Special Features

All of the following PID Control-algorithm options and special features apply to the PID
with External Reset Feedback algorithm:

• 8.14.1.3.1 Interactive and Noninteractive PID Forms

• 8.14.1.3.3 Four Combinations of Control Terms
• 8.14.1.3.4 Control By a Single Term
• 8.14.1.3.5 Direct and Reverse Control Action
• 8.14.1.3.6 PV Tracking
• 8.14.1.3.7 Gain Options
• 8.14.1.3.9 Suppression of Output "Kicks" when Switching to Cas Mode
• 8.14.1.3.11 Restrictions on Some Values
• 8.14.1.3.12 Ratio Control
• 8.14.1.3.13 Operating Modes; Man, Auto, Cas and Bcas
• 8.14.1.3.14 Remote Cascade Options
• 8.14.1.3.15 Restart or Point Activation
• 8.14.1.3.16 Error Handling

8.14.3.3.1 Error Handling, RFB and TRFB Inputs

If S1 is Off, and the reset-feedback input has a bad value, the data-point mode doesn't
change and the CV value goes bad (NaN). When the RFB input is again good, the CV
value is initialized (see 8.14.1.5) and the dynamic terms are returned to a steady state. If
configured for external initialization, an initialization request is sent to the primary data
point.

If S1 is On, and the tracking-value input has a bad value, the data-point mode doesn't
change and the CV value goes bad (NaN). When the TRFB input is again good, the CV
value is initialized (see 8.14.1.5) and the dynamic terms are returned to a steady state. If
so configured, an initialization request is sent to the primary data point.

APM Control Functions & Algorithms 8-55 12/03

 8.14.3

PID_PRIM #1 PID_SEC #1

PV OP
SP
SP OP

SPP S1 TRFB

LOGIC #2 LOGIC #2 LOGIC #2

AI_PV AO_PV DI_SPCH AI_SP DI_MAN AO_CV AI_CV

SP_IN SP_ CHNG SP_OUT MAN_STS CV_IN

PV_IN CV_OUT
ANALOG DISPLAY SERVICE

Input Output
From NOTE: #1 SP, AND PV MAY BE CONNECTED TO THE PID_SEC IN A To
SINGLE LOOP CONTROL SITUATION.
Process Process
#2 SEE THE NEXT PAGE FOR DETAILS OF THE LOGIC SLOT
CONFIGURATION.
Fig. 8.15.3-3
2083

Figure 8-10 — Configuration and Wiring Diagram Hand/Auto Station

APM Control Functions & Algorithms 8-56 12/03

 8.14.3

INPUT LOGIC BLOCKS OUTPUT

CONNECTIONS CONNECTIONS

DI.MAN.PVFL L1
(ANALOG_DSP.MAN_MODE)
OR
ALG S01 PID_SEC.S1
AO_CV.INITREG L2

PID_PRIM.SP L3 AO.SP.OP
(ANALOG_DSP.SP_IN)

AI.SP.PV L4 PID_PRIM.SPP
(ANALOG_DSP.SP_OUT) ENB

DI_SP.PVFL L5
(ANALOG_DSP.SP_CHNG)
2084

Figure 8-11 — Logic Point Configuration Hand/Auto Station

8.14.3.3.2 Output Connections

The output of this algorithm can be to any desired destination using control output
connections.

NOTE
Initialization and windup protection normally associated with control output connections are not
performed with this algorithm. That is, initialization occurs only when S1, the tracking switch-
control signal, is true.

Output connections store the value of the OP after converting to engineering units.

See 8.10.6, Control Output Connections, for restrictions on the number of output connections
and destinations for this algorithm.

8.14.3.3.3 Engineering Unit Ranges

PV Engineering unit range (PVEULO and PVEUHI) and the output engineering unit range
(CVEULO and CVEUHI) must be specified. The SP engineering unit range (SPEULO
and SPEUHI) always follows the PV range.

8.14.3.3.4 Operating Modes

The PIDERFB algorithm operates in the following modes:

• Man • Cas
• Auto • Bcas — If RCASOPT = Spc or Ddc or DdcRsp

APM Control Functions & Algorithms 8-57 12/03

 8.14.3
8.14.3.3.5 Remote Cascade Options

All Remote Cascade Options are supported: Spc, Ddc, DdcRsp and Rsp.
8.14.3.4 Equations

If the value in the S1 parameter is On,

TRFB – CVEULO
CV = CVEUHI – CVEULO * 100

For equations A, B, and C, if the S1 value is Off,

K1
CVRFB(s) = K * T1 * (rfb(s) – CV(s))
* s

For equation D, if the S1 value is Off,

1
CVRFB(s) = K * T1 * (rfb(s) – CV(s))
* s

CV = CVPID + CVRFB

Where:

CV = Full-value output in percent, PID combined with CVRFB.

CVPID = The incremental output of the PID computation. This is an internal

parameter and is not available to displays nor to user-written
programs.

CVRFB = The scaled, integrated deviation of RFB from CV. This is an

internal parameter and is not available to displays nor to user-
written programs.

K = Gain

K1 = External, reset-feedback gain

RFB = The external, reset-feedback signal in engineering units. Default = NaN.

RFB – CVEULO
rfb = CVEUHI – CVEULO * 100

s = The Laplace operator.

S1 = The switch-control flag. Default = Off.

TRFB = The tracking value in engineering units. Default = NaN.

T1 = The integral term in minutes per repeat.

APM Control Functions & Algorithms 8-58 12/03

 8.14.3

8.14.3.5 Initialization

Initialization normally associated with output connections is not performed with this
algorithm. Output connections store the value of the OP (after converting to engineering
units based on CVEULO and CVEUHI) to the secondary.

8.14.3.6 Override Feedback Processing

Override-feedback processing is as described under 8.14.1.6; however, use of PIDERFB in

override strategies is not recommended.

8.14.4 Position Proportional Controller (POSPROP)

8.14.4.1 Function

This algorithm manipulates two digital outputs, raise and lower, to drive the PV toward the
SP. The setpoint is typically the desired position of a valve and the PV is the actual
feedback from the process.

Digital outputs are pulsed at a time interval specified by the CYCLETIME parameter and
the pulse width is proportional to the error signal.

This algorithm requires only one input. The number of inputs is defaulted to one; however,
the SP can be fetched with an input connection. PV Source selection is supported if the
point is configured as a full point. The Advisory (ASP) and Target Value (TV) options of
SPOPT (Setpoint Option) are supported.

The Raise/Lower digital outputs are stored to the destinations specified by the parameters
RAISDSTN and LOWRDSTN, respectively. The only valid output destinations are to
pulsed (but not PWM type) digital outputs. The pulse can be ONPULSE or OFFPULSE.

See Figure 8-12.

From Initializing Primary

or
AM Control Strategy

SP

RAISDSTN Digital Output

From PV Algo or IOP PV POSPROP
LOWRDSTN Digital Output

Figure 8-12 — Position Proportional Algorithm Functional Diagram 2085

APM Control Functions & Algorithms 8-58 12/03

 8.14.4

Operator AM Prog Local

Entry Store Cascade

Target Value or Setpoint Processing

SP

100% of Scale

From PV Algo
or I/O Module PV POSPROP PV

0 % of Scale

LOWER

RAISE

Figure 8-13 — Example of Position Proportion in Step Valve Control Strategy 2086

8.14.4.2 Use

This algorithm is used to pulse two digital outputs to drive the process variable toward the
setpoint. This algorithm would typically be used to step a valve open or closed, to raise or
lower a rotary device, or to move plates of a pulp mill refiner together or apart.

8.14.4.3 Options and Special Features

8.14.4.3.1 Modes

All four modes (Man, Auto, Cas, and Bcas) apply. When in Auto, Cas or Bcas modes, the
normal computation is performed. When in Man mode, the output pulses are issued on
operator demand.

APM Control Functions & Algorithms 8-59 12/03

 8.14.4

8.14.4.3.2 Remote Cascade Options

Only the SPC option is supported.

8.14.4.3.3 Output Manipulation in Manual Mode

In Manual mode, the output can be manipulated from the group and detail displays using
the Raise/Lower keys. At the time of configuration, the engineer must define "manual
output pulse time (MANOPTIM)." When the operator presses the Raise key (single up-
arrow), raise output pulse of width equal to MANOPTIM is issued. When the operator
presses the fast raise key (double up-arrow), raise output pulse to width equal to 10 times
MANOPTIM is issued. Lower output pulses can be similarly generated.

8.14.4.3.4 Windup Feedback Limit Switches

Output high and low flags can be set to indicate the status of the limit switches
representing the valve position. When OPHIFL is set, the Raise output pulses are not
generated. When OPLOFL is set, Lower output pulses are inhibited.

OPHIFL and OPLOFL are usually set by output connections on Logic slot based on limit
switch feedback (brought into the system through digital inputs) from the process.

NOTE
In manual mode, the operator can manipulate the output Raise/Lower pulses regardless of the
status of the OPHIFL and the OPLOFL.

8.14.4.3.5 Raise/Lower Output Destinations

The Raise/Lower digital outputs are stored to the destinations specified by RAISDSTN and
LOWRDSTN, respectively. The only valid outputs are to ONPULSE or OFFPULSE of
digital outputs configured as Status type.

8.14.4.3.6 Setpoint Options

Both options, advisory setpoint (ASP) and target value (TV), are supported.

8.14.4.3.7 PV Source Selection

PV source selection and PV alarm reporting are supported.

APM Control Functions & Algorithms 8-60 12/03

 8.14.4

8.14.4.3.8 Engineering Unit Ranges

The PV Engineering unit ranges (PVEULO and PVEUHI) must be specified. The setpoint
engineering unit range (SPEULO and SPEUHI) always follows the PV range. The output
engineering unit range (CVEULO and CVEUHI) does not apply.

8.14.4.3.9 Analog Output Related Parameters

The standard control slot parameters that are normally related to the analog output value do
not apply because analog outputs are not valid destinations for outputs from this algorithm.
The OPHIFL and OPLOFL are explained under 8.14.4.3.4. Other parameters associated
with analog outputs cannot be fetched or stored by any system function. Internally, they are
defaulted such that they do not have any effect on the system functions.

PARAMETER INTERNALLY
NAME DEFAULTED TO

CV NaN

CVEUHI 100.0

CVEULO 0.0

OP -6.9% of Full Scale

OPEU N/A

OPHILM 105.0%

OPLOLM -5.0%

OPROCLM NaN

OPMCHLM 0.0

SAFEOP N/A

NOCOPTS 1

INITMAN Off

APM Control Functions & Algorithms 8-61 12/03

 8.14.4

8.14.4.4 Equations

Only one equation is available. The equation is calculated as follows:

The raise and lower pulses are generated at a rate specified by the cycle time. At the beginning
of each cycle time, the pulse width is calculated and the digital outputs are pulsed as follows:
If CYCLE_TIMER expired:
IF (PVP < (SPP - DEADBAND)) AND (OPHIFL = Off) THEN
Issue a raise pulse of width equal to:
(SPP - PVP)
RAISETIM = K * RAISRATE + DEADTIME

ELSE IF (PVP > (SPP + DEADBAND)) AND (OPLOFL = Off) THEN

Issue a lower pulse of width equal to:
(PVP - SPP)
LOWERTIM = K * LOWRRATE + (RT * DEADTIME)

ELSE Reset the cycle timer to the beginning.

Where: PVP = PV in percent
SPP = SP in percent
DEADBAND = the error deadband in percent (Range = 0.0 to 100.0; Default = 5.0)
OPHIFL = High output windup flag
OPLOFL = Low output windup flag
CYCLETIM = the cycle time in seconds. Range: 0.25 to 1000.0; Default = 10.0
RAISRATE = the raise stroke rate in percent per second. Default = 100.0% per sec
Range: greater than 0.0
LOWRRATE = the lower stroke rate in percent per second.
Range: greater than 0.0. Default = 100.0% per second
RAISETIM = the raise pulse time in seconds. Default = N/A.
It is clamped to the lower of MAXPULSE or CYCLETIM.
If smaller than MINPULSE, no pulse is issued.
LOWERTIM = the lower pulse time in seconds. Default = N/A
It is clamped to the lower of MAXPULSE or CYCLETIM.
If smaller than RP*MINPULSE, no pulse is issued.
K= Gain constant (Range = 0.0 to 10.0; Default = 1.0)
RP = Pulse ratio (Default = 1)
RT = Deadtime ratio (Default = 1)
DEADTIME = Additional pulse time required to overcome friction in the motor
when it begins to move or change direction. It is added to the
computed pulse time except when the pulse issued last cycle time
was in the same direction (as the pulse this time) and the pulse
width was equal to CYCLETIM. Default = 0.0
MAXPULSE = Maximum pulse time limit. If computed pulse time is greater than
this, it is clamped to the lower of MAXPULSE or CYCLETIM.
Default = 60 seconds
MINPULSE = Minimum pulse time limit for raise pulse. If computed pulse is
smaller than this, no pulse is issued. Default = 0.0 seconds.

APM Control Functions & Algorithms 8-62 12/03

 8.14.4

8.14.4.5 Initialization

The Raise and Lower outputs are both set to OFF (or their normal states) and the cycle is
restarted when forward calculation is resumed after initialization.

The SP is set equal to the PV (subject to the setpoint limits) when any of the following
conditions exist:
• The mode is Man.
• The slot is being processed for the first time after becoming active.
• This slot is a secondary within a local (inside the same APM box) cascade control
strategy, and it is going through one-shot control initialization.

NOTE
The one-shot control initialization occurs:

• when the control initialization request flag (CTRLINIT) is On,

• when this slot is being processed for the first time after the APM state has been changed
to RUN (Ok),
• when just recovering from a bad PV.

The position proportional control algorithm is forced to initialize when outputting to a digital
output point that has its INITREQ parameter = ON.

8.14.5 PID Position Proportional Controller (PIDPOSPR)

8.14.5.1 Function

This algorithm can be viewed as a normal PID algorithm joined in cascade with a PosProp
algorithm such that the PosProp part uses the del_cv of the normal PID as its PV to
generate raise and lower pulses. The function of the PID part of the algorithm is the same
as that of the normal PID algorithm except that PidPosPr does not support OP (and OP
related parameters OPEU, OPHILM, etc.) and CV (and CVEUHI, CVEULO). The end part
of the algorithm behaves exactly as a POSPROP algorithm. Figure 8-14 demonstrates the
concept.

APM Control Functions & Algorithms 8-63 12/03

 8.14.5

PV Lower
PID del_cv POSPROP
SP Raise

Figure 8-14 — PID Position Proportional Algorithm Functional Diagram 11016

8.14.5.2 Use

This algorithm is typically used in place of the POSPROP algorithm to operate a motor
driven valve without position feedback.

8.14.5.3 Options and Special Features

8.14.5.3.1 Modes

All four modes (Man, Auto, Cas, and Bcas) apply. When in Auto, Cas, or Bcas modes, the
normal computation is performed. When in Man mode, the output pulses are issued on
operator demand.

8.14.5.3.2 Remote Cascade Options

Only the SPC option is supported.

8.14.5.3.3 Output Manipulation in Manual Mode

In Manual mode, the output can be manipulated from the group and detail displays using
the Raise/Lower keys. At the time of configuration, the engineer must define "manual
output pulse time (MANOPTIM)." When the operator presses the Raise key (single up-
arrow), raise output pulse of width equal to MANOPTIM is issued. When the operator
presses the fast raise key (double up-arrow), raise output pulse to width equal to 10 times
MANOPTIM is issued. Lower output pulses can be similarly generated.

8.14.5.3.4 Windup Feedback Limit Switches

Output high and low flags can be fetched using the input connection parameters Output
High and low Flag Input Source (OPHISRC) and (OPLOSRC), respectively. These flags
serve the same function as the similar flags for POSPROP.

8.14.5.3.5 Local Manual Support

The Local Manual state is supported and it can be fetched with an input connection using
the input parameter Local Manual Source (LMSRC).

APM Control Functions & Algorithms 8-64 12/03

 8.14.5
8.14.5.4 Equations

Only one equation is available. The equation is calculated as follows:

If CYCLE_TIMER expired:
IF ((ACCUMULATED_DEL_CV > DEADBND) AND (OPHIFL = OFF))
Issue a raise pulse of width equal to:

ACCUMULATED_DEL_CV
RAISETIM = K1 * RAISRATE + DEADTIME

ELSE IF (ACCUMULATED_DEL_CV < ( - DEADBAND)) AND (OPLOFL = OFF)

THEN

Issue a lower pulse of width equal to:

(-ACCUMULATED_DEL_CV)
LOWERTIM = K1 * LOWRRATE + (RT * DEADTIME)

ELSE Reset the cycle timer to the beginning.

Where: ACCUMULATED_DEL_CY = the accumulations of del_cv (of the PID

part) during this cycle.
K1 = the Gain constant for the POSPROP part of the algorithm. It is
renamed K1 (was K for the POSPROP algorithm) to avoid
confusing it with the PID gain constant K.
DEADBAND = the error deadband in percent (range = 0.0 to 100.0;
default = 5.0)
OPHIFL = High output windup flag
OPLOFL = Low output windup flag
RAISRATE = the raise stroke rate in percent per second. Default = 100.0%
per sec
Range: greater than 0.0
LOWRRATE = the lower stroke rate in percent per second.
Range: greater than 0.0. Default = 100.0% per second
RAISETIM = the raise pulse time in seconds. Default = N/A.
It is clamped to the lower of MAXPULSE or CYCLETIM.
If smaller than MINPULSE, no pulse is issued.
LOWERTIM = the lower pulse time in seconds. Default = N/A
It is clamped to the lower of MAXPULSE or CYCLETIM.
If smaller than RP*MINPULSE, no pulse is issued.
RT = Deadtime ratio (Default = 1)
DEADTIME = Additional pulse time required to overcome friction in the
motor when it begins to move or change direction. It is added to
the computed pulse time except when the pulse issued last cycle
time was in the same direction (as the pulse this time) and the
pulse width was equal to CYCLETIM. Default = 0.0

APM Control Functions & Algorithms 8-65 12/03

 8.14.5
8.14.5.5 Analog Output Related Parameters

Parameters related to the analog output value do not apply and are defaulted to the same
values as those similar parameters in the PosProp algorithm.
8.14.5.6 Safety Shutdown

The Shutdown flag, when turned on, causes the mode to go to MAN with OPR attribute
and the output is derived based on the value of a new parameter SAFOPCMD as follows:
When:
SAFOPCMD = Idle No more output pulses are issued.
SAFOPCMD = Raise Raise pulses are issued until the PV is > EUHI, or OPHIFL
is ON. If the PV is bad, the test for PV > EUHI is ignored.
SAFOPCMD = Lower Lower pulses are issued until the PV is < EUHI, or OPLOFL
is ON. If the PV is bad, the test for PV < EUHI is ignored.
8.14.5.7 Bad PV/Mode Shed

For PidPosPr (and PosProp) algorithms, Shed Hold, Shed Low, High, and Shed Safe are
interpreted as follows:
BADCTLOP Action Taken for PIDPosPr (and PosProp)
No Shed IDLE, No more output pulses are issued.
Shed Hold IDLE
Shed High Raise, Raise pulses are issued until PV > EUHI or OPHIFL is ON.
If the PV is bad, the test for PV > EUHI is ignored.
Shed Low Lower, Lower pulses are issued until the PV < EUHI or OPLOFL is
ON. If the PV is bad, the test for PV < EUHI is ignored.
Shed Safe Handled like Shutdown based on the value of
SAFOPCMD.
8.14.6 Ratio Control (RATIOCTL)
8.14.6.1 Function

This algorithm calculates a setpoint for a PID algorithm that is the desired ratio of a
controlled variable to an uncontrolled variable. The value of the controlled variable is
maintained at a specified ratio of the value of the uncontrolled variable. The data point that
uses this algorithm usually uses Calculator PV algorithm to calculate the measured value
of the ratio for displays and reports.
Ratio control can also be accomplished with the ratio-bias options of the PID or PID
Feedforward control algorithms (see 8.14.1, 8.14.2). This Ratio-control algorithm has
several advantages, including the display of the actual ratio attained as calculated by the
Calculator PV algorithm and direct control of the ratio through the SP of the Ratio
algorithm.

APM Control Functions & Algorithms 8-66 12/03

 8.14.6

Figure 8-15 — Functional Diagram, Ratio Control Algorithm 1334

8.14.6.2 Use

This algorithm is typically used in the control of the flow of a gas or fluid, as a ratio of an
another flow. For example, in a furnace, the air supply might be controlled as a ratio of the
fuel supply. If more heat is required to maintain combustion efficiency, the fuel flow is
increased and the air flow can be increased as a ratio of the fuel-flow increase.

Figure 8-16 shows an example of such an application. In this example, the data point that
uses the Ratio-control algorithm also uses the Calculator PV algorithm to calculate the
actual ratio achieved, for display or printing. The Calculator PV should use the filtered
value (X2FILT) of the uncontrolled variable.

To evaluate this example, see the equations under 8.14.6.4 and you will note that the same
scale factor, 0.7, is used for P1 in the PV algorithm and for K1 in the Ratio-control
algorithm. The resulting scaled ratio between the "other" flow and the controlled flow is
2.00/0.7 = 2.857, so if the "other" flow is 6.00 gallons per minute, the controlled flow must
be 6.00*2.857 = 17.143 gallons per minute.

The 0.7 scale factor is used for C1 and K1 in the example to illustrate that the same scale
factors and bias values must be used with the PV algorithm and the Ratio-control
algorithm (K1 = C1, K2 = C2, B1 = C3, and B2 = C4), so that the actual ratio calculated
by the PV algorithm will be the same as the desired ratio (2.00) when the loop is stable. If
the scale factor in C1 and K1 were 1.0, the controlled flow would stabilize at the "other"
flow, multiplied by the ratio. In the example of Figure 8.15, the controlled flow would be
6.00*2.00 = 12.00 gallons each minute. In any case, the controlled flow stabilizes at a
value equal to the "other" flow, multiplied by the desired ratio, as modified by any scale
factors other than 1.0 or any bias values other than 0.

APM Control Functions & Algorithms 8-67 12/03

 8.14.6

PVCALC = C1 * P1/P2 = 0.7* 7.143/6.00 = 2.00

"Wild"
P2 Multiplier/ PVAUTO
Flow
Divider
=6.00 P1 2.00
PV Algorithm
GPM
PV
PVMAN,
PVSUB Available for displays and reports
CV = /SP * X2/K1 = 2* 6/0.7 = 17.143
X2
RATIOCTL CV OP
SP SP

Desired Ratio = 2.00 PID

PV

17.143 GPM
Controlled Flow

Figure 8-16 — Ratio Control Example 1335

8.14.6.3 Options and Special Features

8.14.6.3.1 Control Input Connections

This algorithm requires two input connections, for PV processing and X2. The number of
input connections is defaulted to 2; however, it can be increased to 3, allowing the SP to be
fetched with an input connection.

8.14.6.3.2 Engineering Unit Ranges

The PV engineering unit range (PVEULO and PVEUHI) must be specified. The setpoint
engineering unit range (SPEULO and SPEUHIU) always follows the PV range. The output
engineering unit range (CVEULO and CVEUHI) is derived from the secondary if the
number of output connections is greater than 0; otherwise, it must be specified.

APM Control Functions & Algorithms 8-68 12/03

 8.14.6
8.14.6.3.3 Role of the Calculator PV Algorithm

Any data point that uses RATIOCTL should use the Calculator PV algorithm (7.7.9).
X2FILT, the filtered value of the uncontrolled variable X2 is connected to P2 and the
variable controlled by the PID algorithm (see Figure 8-16) is connected to P1. The scale
factors and bias values in the Calculator PV algorithm must have the same values as their
counterparts in the Ratio Control algorithm:

RATIOCTL CALCULATOR

K1 = C1
K2 = C2
B1 = C3
B2 = C4

Thus, Calculator can calculate the actual (measured) ratio attained, and when the
PVSOURCE is Auto, that value is available in the PV parameter of the data point for use
on displays and reports.

8.14.6.3.4 Operating Modes

The RATIOCTL algorithm operates in the following modes:

• Man

• Auto

• Cas

• Bcas—if RCASOPT = Spc

8.14.6.3.5 Remote Cascade Options

Only the Spc option is supported.

8.14.6.3.6 Restart or Point Activation

On a cold or warm restart or when the RATIOCTL data point is activated, initialization
takes place as described under 8.14.6.5.

8.14.6.3.7 Error Handling

If the value status of the X2 input is bad, the CV value is changed to bad (NaN). The data
point remains in the same mode. When the X2 input again has normal status, initialization
takes place as described under 8.14.6.5.

APM Control Functions & Algorithms 8-69 12/03

 8.14.6
8.14.6.3.8 Operator Entered Bias (BO)

In R600 or later, the Algorithm includes an operator-entered bias. This Bias parameter
value is added after all other calculations to obtain the CV for print. For equivalent
operation when migrating from PRE R600 Releases set BO = 0.0.
8.14.6.3.9 Initialization Ramping Bias

The bias B is made up of two components, BO and BI, where BO is the operator entered bias and BI
is the internal bias. An optional initialization method using an internal ramping bias is available.
Parameter RATE1 specifies the decay rate for the Internal Bias, BI. The value of BI is set during the
algorithms initialization and decays to zero at a rate defined by RATE1.
Compatibility—If RATE1 is set to NaN, the initialization ramping value is set to 0.0 and
the initialization value for the primary is determined by back calculation compatible with
PRE R500 functions. When migrating from R4xx or R5xx to R600, the fixed bias term BO
should be defaulted to 0.0.
When RATE1 = NaN
K1 * (CV - BO) + BI
INITVAL =
K 2 * X 2 FILT + B 2
If RATE1 is set to a non-zero value, and the Ratio Control block is in Cascade mode, the
SP value is back calculated. During initialization, an internal bias that is equal to the
difference between the old CV value and the new CV value is added to the output
calculation to produce a bumpless output Internal Bias (BI) is calculated as follows:
SP * ( K 2 * X 2 FILT + X 2) - BI
BI = CVold – -BO
K1
where CVold is the last calculated CV value before initialization.

If the primary accepts the initialization value (INITVAL), then BI turns out to be zero. If
the primary does not accept the initialization value, then BI turns out to be non-zero. If not
zero, the internal bias (BI) decays at the rate specified by RATE1. RATE1 is specified in
engineering units per minute. If RATE1 = 0, then BI does not decay but remains fixed.
If the Ratio Control block operates in Auto mode during initialization when the mode changes
from manual to auto, the internal bias (BI) is added to the output. BI decays at the rate
specified by RATE1 as described for Cascade mode. The default value of RATE1 = NaN.

APM Control Functions & Algorithms 8-70 12/03

 8.14.6
8.14.6.3.10 X2 Filter

At the X2 input to the Ratio Control block, the value of the uncontrolled variable is filtered
by a single lag filter. Parameter X2TF determines The X2 filter time (0 - 60 minutes) and
X2FILT is the filtered value of X2. The X2FILT value appears on the point detail display.
This filter is active only if the point is in the AUTO or CASC mode.

Compatibility—When X2TF is set for 0.0 minutes lag time, X2 is not filtered as was the
case for the algorithm prior to Release 500.
The default value of X2TF = 0.0.
8.14.6.4 Equations

The equations are as follows:

• Calculator PV Algorithm
(C1 * P1 + C 3)
PVCALC =
(C 2 * P 2 + C 4)

Where (see Figure 8.15)

PVCALC = The calculated, actual ratio achieved.
C1 = P1 scale factor. Must equal K1 of the RATIOCTL algorithm
Default value = 1.0.
C2 = P2 scale factor. Must equal K2 of the RATIOCTL algorithm
Default value = 1.0.
C3 = Bias constant P1 input. Should be the same value as B1in the
RATIOCTL algorithm. Default value = 0.
C4 = Bias constant P2 input. Should be the same value as B2 in the
RATIOCTL algorithm. Default value = 0.
P1 = The controlled process variable. Source should be the same as
the PV of the PID controller that is RATIOCTL's secondary.
P2 = The filtered value (X2FILT) of the uncontrolled process
variable. If there is a PID-controller controlling this other flow,
the PV of that PID could be the source for P2 and X2.
• Ratio Control Algorithm
SP * ( K 2 * X 2 FILT + B 2) - BI )
CV = +B
K1
Where (see Figure 8-16)
B = The overall bias value (= BO + BI)
BI = Internal bias
BO = Fixed output bias
CV = The calculated output in engineering units
SP = The desired ratio input
X2FILT = The filtered value of the uncontrolled process variable X2.

APM Control Functions & Algorithms 8-71 12/03

 8.14.6
BI = Internal Bias.
B1 = Bias constant. Should be the same value as C3 in the
CALCULTR PV algorithm. Default = 0.
B2 = Bias constant for the X2 input. Should be the same value as C4
in the CALCULTR PV algorithm. Default = 0.
K1 = The ratio scale factor. Must equal C1 of the CALCULTR PV
algorithm.
K2 = The scale factor for X2. Must equal C2 of the CALCULTR
algorithm.
8.14.6.5 Initialization

When the data point is initialized, an initialization request is sent to the primary, and the
initialization value to be applied by the primary to the SP input is calculated and sent to the
primary as follows:
K1 * (CV - BO) + BI
INITVAL =
K 2 * X 2 FILT + B 2

Refer to 8.14.6.3.8 Ramping Bias for a more complete discussion.

From Initializing
Primary
CAS

SP RATIOCTL

AUTO CV OP X1 CV
X2 Override
X3 SELECTOR
X4

To I NITVAL PTORST
Primary PTORST ORFBSEC
ORFBSEC
ORFBSEC is not an external parameter.

Figure 8-17 — Override Feedback Processing 1336

8.14.6.6 Override Feedback Processing

When the data point's secondary uses an Override Selector algorithm (see Figure 8-17), the
following functions take place if the RATIOCTL algorithm if it is in Cas mode:
• The override status is sent to the primary data point in PTORST (Point Override
Status).
• If the status in PTORST is not selected, a feedback value, calculated as follows, is sent
to RATIOCTL's primary data point.

APM Control Functions & Algorithms 8-72 12/03

 8.14.7
K1 * (ORFBSEC - B) + BI
ORFB =
K 2 * X 2 FILT + B 2
Where ORFBSEC is the override-feedback value received from the secondary data
point.
For more detail on override control, see 8.13 of this publication.

8.14.7 Ramp and Soak (RAMPSOAK)

PV RAMPSOAK CV OP SP PID
CV OP
PV
PV Output
Algorithm Processing

FT

SOAKT3
SOAKV3
SOAKT2
RATE3 SOAKT4
CV SOAKV2 RATE4
SOAKT1
RATE2 SOAKV4
SOAKV1
RATE1

Time

Figure 8-18 — Functional Diagram of Ramp and Soak Control Algorithm 1337

8.14.7.1 Function

This algorithm is typically used as a setpoint programmer. It produces an output that

consists of up to 12 alternate ramps and soak periods—a total of 24 segments. Twelve
pairs should be enough to cover most applications commonly encountered; however, if
longer ramp and soak sequences are required, four such algorithms can be configured to
push to a control switch algorithm. Then, using logic, the switch could select one of the
ramp and soak algorithms. See 8.14.7.3.8.

When not used in connection with the switch algorithm, output from this algorithm is
usually used as the setpoint for a secondary data point that uses a PID algorithm to control
a process variable, according to the ramps and soak periods. The PV of a data point that
uses RAMPSOAK is normally the PV of the PID point.

APM Control Functions & Algorithms 8-73 12/03

 8.14.7
8.14.7.2 Use

RAMPSOAK is principally used for automatic temperature cycling in furnaces and ovens.
It can also be used for automatic startup of units, and for simple batch-sequence control
where the batch sequence is part of a process that is otherwise a continuous process.

8.14.7.3 Options and Special Features

8.14.7.3.1 Single or Cyclic Sequencing

Once started, the configured sequence of ramps and soak periods repeats itself, if it is not
stopped by an operator or by a user-written program. A Universal Station operator can put
the point in Man mode to freeze the sequence, and then return it to Auto to continue the
sequence.

A configuration parameter called cycle option (CYCLEOPT = Single or Cyclic) is

provided that optionally permits the cycle to stop after completing a single cycle. This
works as follows:

• CYCLEOPT = Single

When the mode is changed from Man to Auto, the algorithm cycles through the
configured rampsoak sequence until the last soak segment is completed. At this point,
the mode is switched back to Man and the current segment ID is set to RAMP1 (the
first segment). Another sequence can now be executed by simply switching the mode
back to Auto.

• CYCLEOPT = Cyclic

When the mode is changed from Man to Auto, the algorithm cycles through the
configured rampsoak sequence until the last soak segment is completed. At this point,
the current segment ID is set to RAMP1 (the first segment) and the whole cycle is
repeated.

APM Control Functions & Algorithms 8-74 12/03

 8.14.7
8.14.7.3.2 Operational Modes

The operating modes establish the operating state of the RAMPSOAK algorithm as
follows:

• Man—The sequence is stopped and the ramp/soak timers are not running.

• Auto—The sequence is running.

Further functions in each mode are the following:

• Man mode

– The Ramp and Soak actions are suspended.

This allows the user to enter starting output value for the Ramp/Soak profile and
to change the value during profile.

– The timers are stopped and hold the last value.

– The value in CV is replaced by the OP value (after converting to EUs).

– SP = CV (SP doesn't affect the output but can be seen at Universal Stations and
user-written programs).

• Auto Mode

– If the current segment is a ramp, and if the guaranteed ramp conditions are OK
(see 8.14.7.3.6),

CV changes at the ramp rate.

If CV should overshoot the next soak value it is clamped at that value, the
remaining soak-time (REMSOAKT), the current-segment (CURSEGID), and
the mark timers and flags (see 8.14.7.3.7) are updated.

– If the guaranteed ramp conditions are not OK, the mark timers (see 8.14.7.3.7) are
stopped.

– If the current segment is a soak, and if the point just changed from Man to Auto,
or just started the soak segment, and the guaranteed soak time conditions are not
OK (see 8.14.7.3.5),

The soak timer doesn't start.

CV remains at its last value.

The mark timers (see 8.14.7.3.7) are stopped.

APM Control Functions & Algorithms 8-75 12/03

 8.14.7
– If the guaranteed soak-time conditions are OK,

The soak timer begins to run or continues to run.

CV holds at its last value and the mark timers and flags (see 8.14.7.3.7) are
updated.

The remaining soak time (REMSOAKT) is adjusted.

If the soak timer times out, the current segment (CURSEGID) becomes the next
ramp segment.

– In any case, in Auto mode, SP is equal to CV. SP doesn't affect the output but can
be seen at Universal Stations and by user-written programs.

NOTE
If the polarity of the ramp rate is opposite to the soak target value, the output jumps to the soak
target value. That is, the ramp segment for this ramp/soak cycle is omitted and the
next segment is invoked.

8.14.7.3.3 Remote Cascade Options

Remote cascade options are not supported.

8.14.7.3.4 Changing Remaining Soak Time and Current Segment

When the RAMPSOAK point is in Man mode, an operator at a Universal Station can
change the remaining soak time (REMSOAKT) if the current segment is a soak.

Also, when the point is in Man mode, an operator can change the current segment
(CURSEGID).

When the mode is returned to Auto the sequence continues, as modified by these changes.
If the segment was changed, the sequence resumes with the new segment, which can be a
ramp or a soak.

Because changes to these parameters don't change the mark functions (see 8.14.7.3.7),
except if CURSEGID is a lower segment than the mark segment (SnSEGID), operators
should not be allowed to change REMSOAKT or CURSEGID when the mark functions
are configured.

APM Control Functions & Algorithms 8-76 12/03

 8.14.7
8.14.7.3.5 Guaranteed Soak-Time

This feature guarantees that the PV is at the proper soak value before the soak-time
measurement begins.
If, when a soak segment begins or is resumed by switching from Man to Auto, the PV is
not within a user-specified deviation (MXSOKDEV) from the SP value (SP always equals
CV), the soak timer doesn't start. When the deviation is within the MXSOKDEV value, the
timer is started and continues, even if the deviation again exceeds MXSOKDEV.
Because the PV could be above or below SP, it is the absolute value of the deviation that is
checked against MXSOKDEV.
To bypass this check you can change MXSOKDEV to NaN.
The soak timer can also be kept from starting when HOLDCMD is On. This allows you to
use a Logic Slot to set HOLDCMD to hold the soak timer until some other condition is
met.
HOLDCMD also affects the guaranteed ramp function. See 8.14.7.3.6.

8.14.7.3.6 Guaranteed Ramp Rate

This feature guarantees that the PV keeps up with the desired value indicated by SP (SP
always tracks CV).
You can specify a maximum ramp-deviation value in MXRMPDEV. There are two
conditions that cause the ramp to stop to wait for the PV to catch up with SP. They are
• RATEn > 0
and
PV < (SP - MXRMPDEV)

• RATEn < 0
and
PV > (SP + MXRMPDEV)
These checks are bypassed if MXRMPDEV contains NaN.
Another condition that stops the ramp is HOLDCMD containing On. You can use a logic
slot to set HOLDCMD to stop or hold the ramp until some condition that you specify is
met.
The content of HOLDCMD also affects the guaranteed soak-time feature. See 8.14.7.3.5.

APM Control Functions & Algorithms 8-77 12/03

 8.14.7

Soak Timer Begins

By assuring that PV = proper soak value, the

user is assured of, for example, the proper
RAMP wait time between phases of a warm up or that
temperature is held for the proper length of
CV = SP PV time during heat treating.

Figure 8-19 — Wait Time Between Phases (Ramp/Soak Algorithm) 11017

By ensuring that the ramping "waits" for the

process to catch up, we never have a large
CV = SP error caused by setpoint change.

PV

Figure 8-20 — Ramping Waits for Process 11018

8.14.7.3.7 Mark Timer Functions

Two flags are provided with the RAMPSOAK algorithm to indicate to other data points
that a specified time has elapsed from the beginning of a specified ramp segment or soak
segment. These mark-timer flags are S1 and S2.

Each of these flags has three associated parameters that specify the segment in which the
flag is set On, the time counted from the beginning of the segment, and the time from the
beginning of the segment until the end time (when the flag is set Off). These parameters
are as follows:

Flag Segment Beginning Time End Time

S1 S1SEGID S1BGNTIM S1ENDTIM

S2 S2SEGID S2BGNTIM S2ENDTIM

APM Control Functions & Algorithms 8-78 12/03

 8.14.7

NOTE
For example S1SEGID = 2
S1BGNTIM = 5 min
S1ENDTIM = 6 min • S1BGNTIM must be less than
Pulsewidth = ENDTIM-BGNTIM or equal to S1ENDTIM.
(Same is true for S2 parameters.)
SEG1 SEG2
5 6 • S1ENDTIM is not required to

—
—
—
—— —
—— —
terminate the marker within the
segment specified by S1SEGID. For
example, if Segment 2 is only 5.5
minutes long, then the marker will
remain on until 6 minutes after the
S1 start of Segment 2 (which is 0.5
minutes into Segment 3).
Timer Starts

Figure 8-21 — Ramp Soak Mark Timers 11019

The S1 or S2 flag is turned on at the number of minutes after the specified segment begins,
as is specified in SnBGNTIM. The corresponding flag is turned Off at the number of
minutes after the specified segment begins, as specified in SnENDTIM.

The following functions also take place:

• At the end of the last segment in the sequence, the S1 and S2 flags are turned Off and
the timers are reset.

• When a ramp or a soak segment is held up by the guaranteed-ramp or the guaranteed-

soak functions, the mark timers are suspended.

• The mark timers suspend when the data point is in Man mode and the S1 and S2 flags
are unchanged.

• If the remaining soak time (REMSOAKT) is changed (in Man mode), the mark timers
are not affected.

• If the current segment (CURSEGID) is changed (in Man mode) to a segment that is
earlier than or equal to a segment specified by SnSEGID, the corresponding mark flag
goes to Off and its timers are reset. If a later segment is specified in CURSEGID, the
flags and timers are not affected.

APM Control Functions & Algorithms 8-79 12/03

 8.14.7

8.14.7.3.8 Achieving Longer Sequences by Interconnecting RAMPSOAK Points

RSK1
SP OP
X1
PV S1

To Logic
OP
RSK2
SP OP
X2

PV S1 S1
S2
To Logic
TRACKING
EQUATION B

LOGIC

RSK1.S1 L1 SWITCH.S2
PULSE
RSK2.S1
L2 SWITCH.S1
PULSE

PROCESSING ORDER:

LOGIC RSK1 RSK2 SWITCH

2092

Figure 8-22 — Use of Logic Slot and Switch to Achieve Additional RampSoak Segments

A sequence of more than 12 ramp and soak segments can be attained by interconnecting
RAMPSOAK points. A Logic Slot can be used with a Switch Algorithm (see 8.14.10) to
select any of the four RampSoak Algorithm data points.

Longer sequences can be accomplished by setting the S1 Mark Flag at the end of the last
soak segment (S1 must be on for at least one sample time).

A Logic point reads the S1 Mark Flag and, using a pulse Logic Block (Pulse width can be
one sample time), sets the corresponding S input on the Switch Algorithm. This causes the
next RampSoak to become selected and all nonselected RampSoaks are INIT. The Switch
Algorithm should be configured for tracking and Equation B.

APM Control Functions & Algorithms 8-80 12/03

 8.14.7
8.14.7.3.9 Engineering Unit Ranges; Setpoint , Output and Deviation Limits

The PV engineering unit range (PVEULO and PVEUHI) and the output engineering unit
range (CVEULO and CVEUHI) must be specified. The setpoint engineering unit range
(SPEULO and SPEUHI) always follows the PV range.
If the RAMPSOAK data point uses a PV algorithm, the setpoint EU range is the same as
the PV EU range, and can't be differently configured. You should configure this point's PV
EU range to be the same as the SP EU range of the secondary point that is receiving this
point's output.
The setpoint and output limits do not apply. Setpoint limits are not available at all, and the
output limits are defaulted to -6.9% to 106.9% and cannot be changed.
The deviation limits (MXRMPDEV and MXSOKDEV) apply to all segments in the
sequence.
8.14.7.3.10 Restart or Point Activation

On a cold restart, a warm restart, or when the data point is activated, the mode goes to Man
and the CV value is NaN. All timers are reset, and the current segment ID is made equal to
the first ramp segment.
No special action occurs on a hot restart and the operation continues from where it was.
8.14.7.3.11 Control Input Connections

The ramp soak control algorithm requires only one control input connection (for PV). The
number of control input connections is fixed at one.
In a typical application, the output of this algorithm provides the SP of a secondary
controller (which is usually a PID control algorithm). The PV of the secondary controller is
then fetched with a control input connection into the PV of the RAMPSOAK. If used in
some different way such that the PV is not available from the secondary, the PV of the
RAMPSOAK should be fetched from its own SP parameter.
8.14.7.4 Equations

There are no configurable equations for the RAMPSOAK algorithm. The ramp and soak
segments are specified in the following parameters (also see Figure 8.18):
• Number of ramp/soak segment-pairs in the sequence—NORSSEQ
Default = 2
• Ramp Rates, EUs per minute—RATE1 through RATE12
Default = NaN
• Soak values—SOAKV1 through SOAKV12
Default = NaN
• Soak times, in minutes—SOAKT1 through SOAKT12
Default = 0

APM Control Functions & Algorithms 8-81 12/03

 8.14.7

8.14.7.5 Override Feedback Processing

This algorithm does not participate in override-feedback processing.

8.14.7.6 RAMPSOAK Parameters

All of the significant parameters associated with the RAMPSOAK algorithm have been
described. Refer to the Advanced Process Manager Parameter Reference Dictionary for
additional parameter information.

8.14.8 Auto Manual (AUTOMAN)

8.14.8.1 Function

In cascade mode, this algorithm calculates a control output that is equal to the input value
plus a bias value. The bias value is normally provided by a Universal Station operator. In
manual mode, the output is controlled by a Universal Station operator or a user-written
program. See Figure 8-23.

Equation A is designed to provide "bumpless" returns to cascade operation, even though its
primary data point may not accept the initialization value from the AUTOMAN data point.
Equation B provides automatic balancing of the biases between several auto manual
stations and "bumpless" closing of cascades, with ramping of the initialization component.

8.14.8.2 Use

The AUTOMAN control algorithm typically serves as the ultimate secondary data point in a
cascade-control strategy. As such it directly drives the control element (valve) through an
analog output slot (a slot using a PID algorithm). See Figure 8-24.

This algorithm is very useful for a secondary data point that is one of two or more
secondaries of the same primary data point (a "fan-out" configuration). In such a
configuration, AUTOMAN can provide a "bumpless" output even if its primary doesn't
accept AUTOMAN's initialization request, but accepts one from one of its other
secondaries. This might happen because the AUTOMAN point is temporarily out of the
cascade because it is inactive or because it is in Man mode.

For an example of output from a PID controller to two auto manual stations, see the
example under Equation B (8.14.8.4).

APM Control Functions & Algorithms 8-83 12/03

 8.14.8

CAS
o o
MAN
From Primary o
Data Point
Output
CAS Processing
o
o X1
o To
MAN CV OP
Secondary
AUTOMAN

To
Primary INITVAL

CV = X1 +B

Where :

X1 = Input (usually from a Primary PID controller)

B = BO + BI

B = Overall Bias, consisting of:

Equation A:

BO = Operator-entered bias = K * X2 for Equation B

BI = Initialization Bias Component

Figure 8-23 — Functional Diagram, Auto Manual Control Algorithm 1319

APM Control Functions & Algorithms 8-84 12/03

 8.14.8

PRIMARY Output
DATA POINT Processing

o CAS
o AUTOMAN CV OP
o
Man
Note

To Additional
Secondary
Data Points

NOTE: In a PM, this is an Analog Output point (slot) with PNTFORM = Component.
On a DataHiway this is a CB, MC, or EC point (slot) using a CM, CMA, or DDC
algorithm.

Figure 8-24 — AUTOMAN Serving as Ultimate Secondary in a Fan-Out Configuration 1320

8.14.8.3 Options and Special Features

8.14.8.3.1 "Bumpless" Returns to Cascade Operation

To support the use of this algorithm as one of the secondaries in a fan-out configuration,
special handling of the bias value is provided. When the data point is configured for
external initialization, the bias value, B, consists of two components.
B = BO + BI

Internal adjustment-value storage. Usually BI = 0.

Internal storage for operator-entered or program-entered bias value

When the user or a program enters a bias value in B while in cascade operation, that value
goes to B0 and BI is forced to zero. BI is an internal parameter that cannot be accessed by a
user. B cannot be entered in Equation B.
When the cascade connection is broken (in Man mode, initialization-manual input, etc.) a
value is calculated for the primary to initialize to, as follows:
INITVAL = CV - B0

When cascade operation resumes, the value in BI is calculated as follows:

BI = INITVAL - OPprim

The actual output value from the primary data point (X1 input)

If the primary data point did accept AUTOMAN's initialization value, BI turns out to
contain zero. If the primary did not accept INITVAL, BI contains a value that causes CV to
contain the value it had just before the cascade closed. In either case, CV does not "bump."

APM Control Functions & Algorithms 8-85 12/03

 8.14.8

If BI has a value other than zero, that value ramps to zero at a rate specified by the user in
the RATE1 parameter. RATE1 is specified in engineering units-per-minute or NaN. If
RATE1 is set to NaN, then the internal bias instantaneously changes to 0 and may cause a
bump in the output. If a positive value is entered in RATE1, the value of BI ramps to zero at
a rate specified in the RATE1 parameter. Thus, while the output doesn't "bump" it does
ramp to the new value called for by the input from the primary.
For example, assume that the AUTOMAN data point is operating in Cas mode
X1 = 6
B = 5; BI = 0, BO = 5
CV = X1 + B = 11
RATE1 = 2 units per minute

The mode is changed to Man

INITVAL = CV - BO = 12 - 5 = 7

The operator changed the output value

B = 5; BO = 5, BI = 0

The primary does initialize

OPprim = 7

Go back to Cas mode

X1 = 7

BI = CV - BO - X1 (12 - 5 - 7 = 0)

B = B0 + BI = 5 + 0 = 5
CV = 7 + 5 = 12

Same value as when in MAN mode

Go to Man mode again
CV = 12 (the operator didn't change it)
INITVAL = CV - B = 12 - 5 = 7

B = 5; BI = 0, B0 = 5

This time, the primary doesn't accept INITVAL, and the output of the primary went to nine
units
OPprim = 9

APM Control Functions & Algorithms 8-86 12/03

 8.14.8
Go back to Cas
X1 = 9

BI = INITVAL - OPprim = 7 - 9 = -2

B = 5 - 2 = 3

CV = 9 + 3 = 12

Now, because BI ramps from -2 units to zero, CV changes as follows:

14 Units

12 Units

1 minute (2 units per

8.14.8.3.2 Operating Modes

• Man
• Cas
• Bcas if RCASOPT = Ddc

8.14.8.3.3 Remote Cascade Options

Only the Ddc option is supported.

8.14.8.3.4 Engineering Unit Ranges

You must configure the X1 input range in XEULO and XEUHI. The output engineering
unit ranges (CVEULO and CVEUHI) always follow the X input ranges.

8.14.8.3.5 Restart or Point Activation

On a cold or warm restart or when the data point is activated, initialization takes place as
described under 8.14.8.3.1. On a hot restart, initialization does not occur.

8.14.8.3.6 Error Handling

If the X1 input has a bad-value status (or Equation B and X2 is bad), the CV value is bad
but the data point remains in the same mode. When the bad input returns to normal, CV is
recalculated and an initialization request is sent to the primary.

APM Control Functions & Algorithms 8-87 12/03

 8.14.8
8.14.8.4 Equations

This algorithm has two forms:

Equation A
CV = X1 + B
Where B = B0 + BI
X1 is the input that is typically pushed from the primary PID controller and B is the
overall bias, which consists of the operator set bias component (BO) and the initialization
bias component (BI).
This form of the equation requires NO input connection. The number of input connections
is defaulted to 0; however, it can be increased to 1, allowing the X1 input to be fetched
with an input connection (X1 fetched by connection number 1).
Equation B
CV = X1 + B
Where:
CV = Control algorithm output in Engineering Units
X1 = Initializable input pushed from primary
B = Bias Value, and
B = (K * X2) + BI
X2 = input connection fetched with input connection #1
BI = Initialization Bias Component
X1 is the input that is typically pushed from the primary PID controller and B is the
overall bias, which consists of the automatic bias adjustment (K * X2) and the
initialization bias component (BI). X2 is fetched with an input connection (#1) from a
calculated input. Bumpless closing of cascades is provided the same as in Equation A
(with ramping of the initialization component). The overall Bias B is a read-only
parameter and cannot be stored to.
Equation B requires only one input connection — X2. The number of input connections is
defaulted to one; however, it can be increased to two, allowing the X1 input to be fetched
with input connection #2.
Consider the following example:
If a PID controller outputs to two auto manual stations, the operator may want the total
required offset between the outputs of the two auto manual stations to be distributed
equally above and below the PID's output. The operator can store the bias (= half the
required offset) to the first auto manual station (configured for Equation A). The second
auto manual must be configured with Equation B, have K of -1.0, and get its X2 input
from the B0 parameter of the first one. Thus, whenever the operator changes B0 of the
first auto manual point, the bias of the second point tracks automatically.

APM Control Functions & Algorithms 8-88 12/03

 8.14.8

Alternately, the strategy could be configured so that the bias value is held in a numeric.
Each auto manual point would then fetch the numeric value into its X2 input. In this
configuration, bias balancing is achieved by setting K on the two auto manual stations to
+0.5 and -0.5, respectively.

8.14.8.5 Initialization

Refer to 8.14.8.3.1 for information on when initialization can occur. Initialization

value = CV - B.

8.14.8.6 Override Feedback Processing

When the data point's secondary uses an Override Selector algorithm (see Figure 8-25), the
following functions take place:

• If this point is in Cas mode, Override Status PTORST is returned to this point through
special processing. If that status is "not selected," an override-feedback value is
calculated as follows, and it is passed on to the AUTOMAN data point's primary:
ORFB = ORFBSEC - B

For more details on override control see subsection 8.13 of this publication.

From Initializing Output (OP)

Primary Processing
CAS
o
o X1 CV X1
o X2 Override
AUTOMAN SELECTOR CV
MAN X3
X4

PTORST-(Selected)
To INITVAL
Primary PTORST ORFBSEC
ORFBSEC

ORFBSEC is not an external parameter

Figure 8-25 — Override Feedback Processing 3370

APM Control Functions & Algorithms 8-89 12/03

 8.14.9

8.14.9 Incremental Summer (INCRSUM)

8.14.9.1 Function

This algorithm calculates the sum of the incremental changes in up to four input values. The
output is obtained by adding the sum of the changes in all inputs, after each input is
multiplied by a scale factor. See Figure 8-26.

X1
X2 To
INCRSUM CV OP
X3 Secondary
X4

Output
Processing

Figure 8-26 — Functional Diagram, Incremental Summer Control Algorithm 1322

8.14.9.2 Use

This algorithm is typically used where more than one primary data point is used to
manipulate the setpoint of the same secondary data point. The primaries usually use PID
algorithms, and are connected to an INCRSUM data point. The output from the INCRSUM
data point is connected to the secondary, as shown here. This is sometimes referred to as a
"fan-in connection."

PID
X1
PID X2
INCRSUM CV OP SP Secondary
PID X3
Data Point
X4 PV
PID

Figure 8-27 — Fan-in Connection 2093

APM Control Functions & Algorithms 8-90 12/03

 8.14.9
8.14.9.3 Options and Special Features

8.14.9.3.1 Control Input Connections

This algorithm requires NO input connections. The number of input connections is

defaulted to 2, but it can be increased to up to four. For each input connection, the user
must also specify the destination parameter, X1, X2, X3 or X4.

8.14.9.3.2 Handling of Full Value, Floating PID Outputs

Special handling of the outputs of PID data points is necessary in the Incremental Summer,
because it is the dynamic operation of the PID that is significant—the full-value output is
not significant. As the process variables change, PID outputs have no direct relation to the
input, therefore they are said to be "floating." The incremental summer responds only to
changes in the PID outputs, and calculates a full-value output to be applied to the control
device (valve) in the process or to the secondary data point.

While the PID algorithms handle SPs, PVs, and outputs as percentages of the configured
range, the Incremental Summer performs its calculations in engineering units.

To prevent a primary PID point in Auto or Cas mode from winding-up beyond its own
output limits, every time the Incremental Summer point is processed it changes the PID's
output value to its own CV value after converting to percent. This does not affect the
dynamic changes in the PID outputs.

If a primary PID is in Man mode, the PID's CV is not changed by the Incremental Summer.

The following restrictions apply to the PID points that are the Incremental Summer point's
primaries.
• Each must have only one control-output connection.
• Each must reside in the same APM box.
• Each must be a normal PID (8.14.1) or a PID Feedforward.
8.14.9.3.3 Engineering Unit Ranges

You must configure the X-input ranges in XEULO and XEUHI. The output engineering
unit ranges (CVEULO and CVEUHI) always follow the X input ranges.
8.14.9.3.4 Changes to Incremental Summer Output by User-Written Programs

User-written CL programs in the AM or user-written programs in a Computing Module can

directly store new values in the CV parameter of the Incremental Summer's data point while
the Incremental Summer point is in BCas mode, or if in CAS mode and RCASOPT is not =
DDC, and normally operating. This causes a shift in the CV value but the dynamic changes
continue, because the Incremental Summer dynamically increments or decrements CV each
time the point is processed.

APM Control Functions & Algorithms 8-91 12/03

 8.14.9
8.14.9.3.5 Override Control Strategy

If the Incremental Summer's secondary is an Override Selector data point, and its Override
Status (PTORST) is not selected, the CV of the INCRSUM data point is set equal to the
override feedback value. During the next pass of forward calculation, the incremental
summer computes its CV in the normal fashion.

This is very useful for cases where several feedforward signals are added to the output of a
PID controller (the addition done by the incremental summer algorithm) and the overall
result is fed to an override selector. Because the output of the PID controller tracks the
output of the incremental summer, which in turn tracks the output of the override selector
when not selected, the output of the PID controller is prevented from winding up when not
selected by the override.

8.14.9.3.6 Operating Modes

This algorithm operates only in Man and Cas modes, and in Bcas if RCASOPT = Ddc.
Because the output of each PID primary tracks the OP output value of the INCRSUM data
point, switching this point from Man to Cas does not "bump" the process.

Note: The dynamic correction calculated by a PID primary appears as a change in that data
point's output after it is processed again and the Incremental Summer actually uses this
change as its input. The full-value outputs of PIDs connected to the Incremental Summer
have no meaning.

8.14.9.3.7 Remote Cascade Options

Only the Ddc option is supported.

8.14.9.3.8 Restart or Point Activation

On a warm restart, or point activation, initialization takes place as described under 8.14.9.5.

8.14.9.3.9 Bad Control Handling

When an input becomes bad ( = NaN), it is not used in the calculation. No bad control
alarm is generated. When the bad input returns to a normal value, its use in the output
computation is resumed in the CV calculation without "bumping" the value. This feature
allows adding multiple feedforward signals to the output of a PID controller.

NOTE
If a single feedforward input is needed, the PID feedforward control algorithm should be used.

APM Control Functions & Algorithms 8-92 12/03

 8.14.9
8.14.9.4 Equations

CV is calculated as follows:

CV(n) = CV(n-1) + K1*[X1(n) - X1(n-1)]

+ K2*[X2 - X2(n)(n-1)]
.
.
.
+ Km*[Xm(n) - Xm(n-1)]

Where:

CV(n) = Current full value of the output of this algorithm in

engineering units.
CV(n-1) = Past full value from the data point (value from the last
time the data point was processed).
m = The number of inputs actually used (m = 1 through 4).
K1 through Km = User-specified scale factors (gains). K1 through K4
default to 1.0.
X1(n) through Xm(n) = Current values of each X input in use.
X1(n-1) through Xm(n-1) = Past value of each X input (value from the last time the
data point was processed)

8.14.9.5 Initialization

Initialization occurs in Man mode when the output is indisposable, or when recovering from
a bad CV value (NaN), as follows:

• An initialization request is sent to all primary data points (up-to-four).

• The Incremental Summer's CV value and past values are initialized:

CV(n-1) = CV
X1(n-1) = X1
.
.
.
Xm(n-1) = Xm

APM Control Functions & Algorithms 8-93 12/03

 8.14.10

8.14.10 Switch (SWITCH)

8.14.10.1 Function

This algorithm operates as a single-pole, 4-position rotary switch. An operator at a

Universal Station, a user-written program, or user-configured logic can change the position
of the switch, thereby selecting any one of the four inputs to be the control-algorithm output
value, CV.

Position Controller by Operator,

User-Written Program, or
User-Configured Logic

X1
MAN
X2 CV OP
From up to 4
Other Data
Points CAS
X3
X4 Output
Processing

Equation A: Operator Controls Switch Position

Equation B: Program or Logic Controls Switch Position, Operator can store to

SELXINP if all S1-S4 flags are OFF

Figure 8-28 — Functional Diagram, Switch Control Algorithm 1342

APM Control Functions & Algorithms 8-94 12/03

 8.14.10

8.14.10.2 Use

The SWITCH control algorithm is used to allow the operator at a Universal Station to alter
control strategies by selecting any of four inputs to be passed on to the output, if Equation A
is chosen. If Equation B is chosen, a Logic Slot can change the switch position, or the
operator can store to SELXINP if all four input selection flags (S1, S2, S3, and S4) are
Off.

You can use SWITCH to select inputs from differing sources and to pass them on to a
single destination or you can use more than one SWITCH data point to switch a single
source to differing destinations. Figure 8-29 shows an example of each of these situations.

Either A, B, C, or D is connected to E:

A
B X1
X2
X3 SWITCH CV OP SP E
C
X4
D

F is connected to G or H, or to both G and H:

F X1 SWITCH CV OP SP G

X1 SWITCH CV OP SP H

Figure 8-29 — Switching Examples 1343

8.14.10.3 Options and Special Features

8.14.10.3.1 Control Input Connections

This algorithm requires NO input connections. The number of input connections is

defaulted to 0; however, it can be increased to up to 4. For each input connection, the user
must also specify the destination parameter as X1, X2, X3 or X4.

APM Control Functions & Algorithms 8-95 12/03

 8.14.10

8.14.10.3.2 Engineering Unit Ranges

The X-input engineering unit ranges (XEULO and XEUHI) must be specified for
X-inputs. The output engineering unit ranges (CVEULO and CVEUHI) always follow the
X-input ranges.

8.14.10.3.3 Operator Control of Switch Position--Equation A

If Equation A is chosen, an operator at a Universal Station can change the switch position in
one of two ways:

• By altering the value in SWITCH data-point parameter SELXINP—The value in

SELXINP specifies the Xn input selected. The corresponding S1, S2, S3, or S4 switch
indicator goes On and the other three switch indicators go Off.

• By changing the desired switch indicator from Off to On—When one of the S1, S2, S3,
or S4 indicators is changed to On, all others go Off. SELXINP then indicates the
position selected.

The second method is very useful when operating with custom displays. The displays can
be built to allow the operator to see the positions and strategies selected unless S1 through
S4 are all OFF.

8.14.10.3.4 Control of Switch Positions–Equation B

Equation B is primarily intended for automatic switching between inputs with the help of
logic (or user programs). In the APM, an operator is allowed to change the switch position,
by storing to the SELXINP parameter when configured for Equation B, if all input selection
flags (S1, S2, S3 or S4) are Off.

With Equation B, turning an S1, S2, S3, or S4 indicator On does not turn the others Off, as
it does with Equation A; therefore, the switch position is changed by storing On and Off in
the S1-S4 parameters as follows:

S1 S2 S3 S4 Xn SELXINP

On - - - X1 SELECTX1
Off On - - X2 SELECTX2
Off Off On - X3 SELECTX3
Off Off Off On X4 SELECTX4

Where "-" means On or Off does not affect the switch position.

S1 has the highest priority, S4 has the lowest priority.

APM Control Functions & Algorithms 8-96 12/03

 8.14.10
8.14.10.3.5 Tracking Option

You can configure the SWITCH algorithm for the tracking option, which causes non-
selected inputs to track the selected input value. This allows the switch position to be
changed without "bumping" the output.
When tracking option is configured, the primaries connected to non-selected inputs can be
initialized. Should one of the primaries not accept the initialization value from the
SWITCH data point, the output may bump when that input is selected. (A primary might
not accept an initialization value because it has more than one secondary and accepts
initialization from one of its other secondaries.)

NOTE
For the tracking option to work, the Switch input must come from an APM primary Regulatory
Control point. The output destination from the RegCtl point must specify the Switch point (that is,
the Switch input must be pushed from the RegCtl point).

When SWITCH is included in an override control strategy, the tracking option must be
configured.

8.14.10.3.6 Operational Modes

The Switch-control algorithm operates in the following modes:

• Man
• Cas
• Bcas if RCASOPT = Ddc

8.14.10.3.7 Remote Cascade Options

Only the Ddc option is supported.

8.14.10.3.8 Restart or Point Activation

On a cold or warm restart, or when the SWITCH data point is activated, initialization takes
place, as configured. See 8.14.10.5.
On a hot restart, normal operation resumes with no initialization.

8.14.10.3.9 Error Handling

If a selected input has a bad-value status, the CV value goes bad (NaN), but the operating
mode does not change. When the status of the selected input is again good, CV is
recalculated, an initialization request is sent to the primary data point.

APM Control Functions & Algorithms 8-97 12/03

 8.14.10
8.14.10.4 Equations

Equations A and B:

CV = Xn

n = 1, 2, 3, or 4

SELXINP = The selected input, which can range from SelectX1 through
SelectX4.

S1 through S4 indicate the switch selection, as described under 8.14.10.3.3 or

8.14.10.3.4.

Where:

CV = The control output value in engineering units.

SELXINP = The selected-input. Default = SelectX1.
S1 through S4 = Switch indicators
M = The number of inputs configured. Default = 2.

NOTE
See 8.14.10.3.4 for special information regarding Equation B.

8.14.10.5 Initialization

When an initializing condition occurs, an initialization request is sent to the selected

primary and the initialization value is the present CV value.

If the tracking option is configured (see 8.14.10.3.5), the non-selected primaries are
continually initialized.

8.14.10.6 Override Feedback Processing

If this data point's secondary is an Override Selector point and if this point is in Cas mode,
when override-feedback processing takes place, override status and an override value are
passed to this point's primary. The status is in parameter PTORST.

If PTORST indicates not selected, the value passed to the selected primary in ORFB is
equal to the value received from the secondary in ORFBSEC.

APM Control Functions & Algorithms 8-98 12/03

 8.14.10
8.14.10.7 Switch Parameters

In addition to the parameters already mentioned, parameter TRACKING is associated with

the SWITCH algorithm. Refer to the Advanced Process Manager Parameter Reference
Dictionary.

8.14.11 Override Selector (ORSEL)

8.14.11.1 Function

The Override Selector Algorithm is used with up-to-four PID inputs, all of which are
initializable. The input with the highest value or the input with the lowest value is selected
and passed on to the output of this data point. The algorithm can operate as a simple
selector or an override option can be configured that prevents PID points in an override-
control strategy from winding up. Refer to Figure 8-29.

If the override option is configured (OROPT = On), an operator can put the ORSEL point in
a bypass state and any of the inputs can be bypassed; that is, not used in the algorithm
calculation. Four logical parameters are provided to select the input to be bypassed. These
parameters are BYPASSX1, BYPASSX2, etc. There is an additional parameter, BYPASS.
When BYPASS = On, the input Xn for which BYPASSXn is On is initialized (equal to the
selected input) and not used in the calculation of the output. When all four inputs are
bypassed, the output is maintained at the last values.

All bypass parameters can be stored by the operator, or any system function, but only the
BYPASS parameter is available for changing at the group display level.

8.14.11.2 Use

This algorithm can be used, without the override option, as a simple selector that selects
either the highest or the lowest of the connected and active inputs. With the override option,
it is used for override-control strategies where a process variable is measured and normally
controlled, but where another variable is selected to constrain the controlled variable, under
a specified condition. This is often referred to as "multivariable-constraint control."

Figure 8-31 illustrates an override strategy. The X1 input to the ORSEL point is normally
selected and applied as the setpoint to the fuel-flow controller. If the value of the air flow
multiplied by some ratio exceeds the fuel-flow setpoint, the air flow constrains the fuel
flow.

APM Control Functions & Algorithms 8-99 12/03

 8.14.11

Output
Processing

CAS
X1 To
CV
X2 ORSEL Secondary
MAN X3
X4 ORFBSEC

From
Init.
Primaries Feedback Value
Sel To Primaries
Notsel,
Notcon

CAS

MAN

Selected, Not Selected,

Not Connected Status to
Primaries (Parameter PTORST)

Equation A: HI Selector
Equation B: LO Selector

Figure 8-30 — Functional Diagram, ORSEL Algorithm 2094

In a strategy like that of Figure 8-31, Equation A, the override option is configured. PID
data points connected to non-selected inputs are prevented from "winding up" by forcing
their outputs to track the override feedback signal (ORFBSEC). For more detail on such
strategies, refer to 8.13.

The simple selector (override option not configured) can be set up to initialize one input,
but not all inputs, by using control-input connections for the inputs that are not to be
initialized, and by using a control-output connection from the point that is connected to the
input to be initialized.

NOTE
There are some important guidelines that must be observed when configuring an override-control
strategy. See 8.13 and the configuration information below.

APM Control Functions & Algorithms 8-100 12/03

 8.14.11

SP A ir
PV Cont.

Air

Setpoint X1 ORSEL SP Fuel

Ratio X2 PV Cont.

F
Fuel
If X2 exceeds X1, air flow
constrains fuel flow.

Figure 8-31 — Example of an Override Control Strategy 11023

8.14.11.3 Options and Special Features

8.14.11.3.1 Control Input Connections

This algorithm requires NO input connections. The number of input connections is

defaulted to 0; however, it can be increased to up to 4. For each input connection, a
destination parameter X1, X2, X3 or X4 must be configured.

8.14.11.3.2 Override and Bypass Options

If the override option is configured, PID points connected to non-selected inputs are
prevented from "winding up" by forcing their outputs to track the override-feedback signal
(ORFBSEC).

Override Offset

A configuration parameter called Override Offset (OROFFSET = On) is provided to control

the behavior of any PIDs connected to the non-selected inputs. If Override Offset is
configured, the output of the PID whose override status is not selected is set equal to the
override feedback value, plus gain times error (after converting to percent). If the override
offset is not configured, the output of the PID whose override status is not selected is set
equal to the override feedback value (after converting to percent).

APM Control Functions & Algorithms 8-101 12/03

 8.14.11

Bypass Options and Parameters

When configured as an override selector, any of the inputs X1, X2, X3, and X4 can be
individually bypassed (not used in the algorithm calculation). Four logical parameters are
provided to select the input to be bypassed. These parameters are BYPASSX1,
BYPASSX2, BYPASSX3, and BYPASSX4. An additional parameter, BYPASS is
provided. When BYPASS is On, the input Xn for which BYPASSXn is On is initialized
(set equal to the selected input) and not used in the calculation of the output. When all four
inputs are bypassed, the output is maintained at the last value.

These parameters are available only when the override option is configured (OROPT = On).

All bypass parameters can be stored by the operator, or any system function, but only
BYPASS is available for changing at the group display level.

NOTE: When a selected input is bypassed, all parameters go through 1-shot initialization.

8.14.11.3.3 Engineering Unit Ranges

The engineering-units ranges for the X1 through X4 inputs must be configured in

parameters XEUHI and XEULO. These parameters contain the high and low values for the
range, which is the same for all four inputs. The output engineering unit ranges (CVEULO
and CVEUHI) always follow the X-input range.

8.14.11.3.4 Operating Modes

Because a data point that uses ORSEL is always a secondary to at least one other data point,
this algorithm operates only in the following modes:

• Cas

• Man

• Bcas if RCASOPT = Ddc

8.14.11.3.5 Remote Cascade Options

Only the Ddc option is supported.

8.14.11.3.6 Restart or Point Activation

On a warm restart, or on activating the data point, the CV is initialized to the value returned
from the secondary and an initialization request is sent to all of the primaries.

APM Control Functions & Algorithms 8-102 12/03

 8.14.11

8.14.11.3.7 Error Handling

In Cascade mode with BYPASS Off, if any input has a Bad-Value status, CV's value is bad
(NaN) and the mode doesn't change when the CV value goes bad. Also, in Cascade mode
with BYPASS On, any non-bypassed input (BYPASSXn=Off) that has a Bad-Value status
causes CV to go bad (NaN).

If a bad input, that was causing CV to be Bad, returns to Normal, CV returns to normal, CV
is made equal to OP, and all bypassed primaries are initialized (see subsection 8.14.11.5).

8.14.11.4 Equations

There are two equation choices:

Equation A—Select the higher of the connected, active inputs.
CV = highest of X1 through Xm
Equation B—Select the lower of the connected, active inputs.
CV = lowest of X1 through Xm
Where
CV = The control-algorithm output in engineering units
X1 through X4 = The four available inputs
M = The number of inputs configured. Default = 2.
For either equation
SELXINP = The selected input: SelectX1 through SelectX4. If more than one
input has the highest (EqA) or the lowest (EqB) value, the lower-
numbered input is selected, e.g., if X2 and X3 have exactly the
same highest value (EqA) SELXINP contains SelectX2.

8.14.11.5 Initialization

Initialization requests from secondary points are ignored as long as the ORSEL output is
disposable.

If the ORSEL is initialized because it is in Manual mode, the output is indisposable, or it

has just returned from bad control status, CV is made equal to INITVAL from the
secondary, and SELXINP is set to None. When the ORSEL is in Manual mode, an
initialization request is passed on to all primaries with an initialization value equal to CV.
When the ORSEL is initializing because the output is indisposable or it is returning from
bad control, an initialization request is passed on to all primaries whose input are bypassed
(BYPASS = On and BYPASSXn = On) with an initialization value equal to CV.

APM Control Functions & Algorithms 8-103 12/03

 8.14.11
8.14.11.6 Override Feedback Processing

8.14.11.6.1 Override-Feedback Initiation

If the override option is configured for the ORSEL point and the ORSEL point is in Cas
mode and not initializing, it propagates override-feedback information to its primary points
and on "upstream."
When BYPASS is Off, the appropriate NotCon, Sel, NotSel status is given to ORSEL's
primaries in PTORST, and the override-feedback value that is passed to the primaries is
calculated as follows:
ORFBSEC = CV

Where ORFBSEC is the feedback value from the secondary. (ORFBSEC is an internal
parameter)
If, under the above conditions, BYPASS is On, the status sent to the primary connected to
the nonbypassed selected input is Sel, NotCon is sent to the bypassed primaries and they are
all initialized. NotSel is set to the nonbypassed non-selected primaries.
If there is more than one Override-Feedback data point in a strategy, only the one nearest
the final control element (the "most downstream" point) initiates override feedback.

8.14.11.6.2 Override-Feedback Propagation

Override-feedback propagation is the passing of status and feedback values, from the
initiating Override Feedback Selector, "upstream" through one or more other data points.

If a "downstream" Override Feedback Selector requests status and value propagation, an

"upstream" Override Feedback Selector" propagates the value and status "upstream," only if

• it is configured as an Override Selector (override configured), and

• it is in Cas mode, and
• its output is disposable.

If so,
If PTORST ( Point Override Status) = SEL (selected), ORFB = CV
else
ORFB = ORFBSEC
Where ORFBSEC is the feedback value from the secondary.

And, PTORST status sent to the selected primary is the same as that received from the
secondary. If BYPASS is false, the status to all other primaries is NotSel. If BYPASS is
true, non-selected inputs are initialized, so the status sent to them is NotCon.

APM Control Functions & Algorithms 8-104 12/03

 8.14.11

8.14.11.7 ORSEL Parameters

In addition to the parameters already mentioned, the following parameters are associated
with the ORSEL algorithm. Refer to the Advanced Process Manager Parameter Reference
Dictionary.

BYPASS

BYPASSX1

BYPASSX2

BYPASSX3

BYPASSX4

CTLEQN

OROFFSET

OROPT

8.14.11.8 Processing Order

Processing order is always important, but especially for the ORSEL strategy. ORSEL
functions will not work properly if point processing order is incorrect.

APM Control Functions & Algorithms 8-105 12/03

APM Control Functions & Algorithms 8-106 12/03
 9

APM BOX FLAG, NUMERIC, STRING,

TIME, AND TIMER GLOBAL VARIABLES
Section 9
This section describes the global variables available in the Advanced Process Manager. They are
the Flags, Numerics, Timers, Times, and String variables. Additional information about the
parameters mentioned in this section can be found in the Advanced Process Manager Parameter
Reference Dictionary.

9.1 GLOBAL VARIABLES

The APM provides the following global variables
• 16,384 Flag variables
• Up to 16,384 Numeric variables
• Up to 16,384 8-character String variables
• Up to 4096 Time variables
• 64 Timer variables
The full 16,384 flags and 64 timer variables are always present. Numerics, strings, and
times are configured by APM Node Specific Configuration parameters such as NSTRING
(number of strings). Configuration is determined by considering the Memory Units needed
for your system (see Section 3). Box global variables do not require any PUs.
Some specific types of points (e.g., Process Module) provide similar local variables.

9.2 BOX FLAG DATA POINT

A Box Flag Data Point is a 2-state (On and Off) point that is used for storing a Boolean
value. The value can be supplied by the operator, by the sequence program, by an output
connection from another APM point, by any APM (or PM) box on the same UCN, or by a
node on the LCN. There are 16384 Flag Data Points (slots) available in an APM box. The
first 2047 flag points are tagable and can be configured as Full or Component points. The
first 4095 Box Flags are accessible from the LCN. The remaining flags must be accessed
through an array point.
Flag data points are not scheduled and only off-normal alarms are processed. Their states
change when they are accessed by other functions such as an operator or a user-written
program.
Flag points do not require a tag name. They can be accessed by !BOX.fl(i) or
$NMxxNyy.fl(i) where xx is the network number and yy is the APM node number. After
configuration, flag variables are initialized to Off. A functional diagram of the Flag Data
Point is shown in Figure 9-1.
As shown in this figure, the input to the flag point is provided by parameter PVFL, which
can be On or Off. PVFL will set the flag-point PV state to the same state as PVFL. The PV
is then available as an output from the flag point and its current state can be accessed by
other points in the APM and in the system.

APM Control Functions & Algorithms 9-1 12/03

 9.2.1
PVFL will also light the STATE1 and STATE0 boxes on the Universal Station Displays,
depending on its state. If PVFL is On, the STATE1 (upper) box will be lighted; if PVFL is
Off, the STATE0 (lower) box will be lighted.

9.2.1 Alarming
The first 128 flag points (slots) can be configured for off-normal alarming. An alarm will be
generated when the PV of the flag point is changed from STATE0 (Off) to STATE1 (On).
Alarming is available only if the flag point has been configured as a Full point.

Group Display

PVFL = On
STATE1

STATETXT(1)

PVFL = Off STATE0

STATETXT(0)

PVFL PV STATE PV

o
PNTFORM

Full o o Componnt

STATE1
HIGHAL
ALENBST
ALARM DETECTION HIGHALPR
Printer (Only for Flag Slots
JnlPrint 1 - 128)
Emergncy
CONTCUT
OFFNRMPR Low
High
Journal EIPPCODE
NoAction

PVNORMAL
PRIMMOD

Figure 9-1 — Box Flag Data Point, Functional Diagram New

APM Control Functions & Algorithms 9-2 12/03

 9.3
9.3 BOX NUMERIC DATA POINT
Numeric Data Points are used to store numeric values that can be used for batch/recipe
operations, or they can be used as a scratch pad to store the intermediate results of
calculations. The values in a numeric point are real numbers that have been entered by the
operator, or by a sequence program, or other system elements. Box Numeric Data Points
are full points and cannot be configured as component points.
Up to 16,384 Numeric slots can be configured as part of each APM box. Numeric slots do
not require a tag name. They can be accessed by !BOX.nn(i) or $NMxxNyy.nn(i) where xx
is the network number and yy is the APM node number. After configuration, numeric
variables are initialized to NaN. An Array point must be used to access index numbers
greater that 4095 over the LCN.
These points are accessible to the sequences in the same APM box, to any APM (or HPM
or PM) box on the same UCN, and to any node on the LCN. The first 2047 Numeric
points are tagable and can be configured as named data points. The first 4095 Box
Numerics are accessible from the LCN. The remaining Numeric variables can be accessed
through an array point.
Numeric data points are not scheduled and are not processed. Their parameter values
change when they are accessed by a system activity, such as by an operator or a sequence
program.
9.4 BOX TIMER DATA POINT
The Box Timer Data Point allows the operator and the sequence program to time the
process events, as required. This type of data point keeps track of the elapsed time after the
timer has been started and provides an indication when the elapsed time has reached the
predefined limit. Box Timer Data Points are component points and cannot be configured as
full points.
There are 64 Timer Data Points in each APM Box, and like box numeric and flag points,
timer data points do not require a tag name. These points are accessible to the sequences in
the same APM box, to any APM (or HPM or PM) box on the same UCN, and to any node
on the LCN. A functional diagram of the Timer Data Point is shown in Figure 9-2.
To use a Timer Data Point, an operator at a Universal Station or the sequence program
loads a preset time value (the length of time that the timer is to run in seconds or minutes)
into parameter SP. Once the preset value is entered, the timer is started by setting parameter
COMMAND to Start. (The timer can also be stopped, reset, or reset and restarted through
the COMMAND parameter.)
The time value in PV starts at zero and increments toward the preset time value when the
timer is processed. (The timer is processed once each second.) The RV parameter indicates
the time remaining until the timer reaches its limit (SP - PV). When PV = SP, the status
parameter SO is set to On to indicate that the time limit has been reached. The values in PV
and SP can range from 0 to 32000 seconds or minutes, as configured.

APM Control Functions & Algorithms 9-3 12/03

 9.5

Minutes, Seconds

TIMEBASE

Preset Time SP SO Status (PV = SP)

TIMER
PV Current Time Value
DATA
Start POINT
RV Remaining Time
Stop (SP - PV)

Reset C STATE Stopped, Running

O
Reset/Restart M
M

Figure 9-2 — Box Timer Data Point, Functional Diagram 11020

9.5 BOX TIME VARIABLES

Time variables can be used to store date/time information such as the date machinery was
put in service, when the machinery was serviced last, when the machinery was last used,
etc.

The APM box provides up to 4096 global Time variables. The maximum limit is
determined by the Node Specific Configuration parameter NTIME (number of times). Time
variables are not configurable with a tag name. They can be accessed by !BOX.TIME(i) or
$NMxxNyy.TIME(i) where xx is the network number and yy is the APM node number. The
first 4095 Box Times are accessible from the LCN. An array point must be used to access
number 4096. After configuration, time variables are initialized to 0.

APM Control Functions & Algorithms 9-4 12/03

 9.6

9.6 BOX STRING VARIABLES

String variables can be used to store descriptive text data such as the brand name or model
of machinery, who to contact for service, etc.

The APM box provides up to 16,384 8-character String variables. The upper limit is
determined by the Node Specific Configuration (box) parameter NSTRING (number of
strings). The first 4095 Box Strings are accessible from the LCN. An array point must be
used to address strings with an index of greater than 4095.

String variables are not configurable with a tag name. They can be accessed by
!BOX.STRn(i) where n is the string length or $NMxxNyy.STRn(i) where xx is the network
number and yy is the APM node number. After configuration, string variables are initialized
to spaces.

APM Control Functions & Algorithms 9-5 12/03

APM Control Functions & Algorithms 9-6 12/03
 10

ARRAY POINTS
Section 10

This section describes the Array point available in the Advanced Process Manager. Additional
information about the parameters mentioned in this section can be found in the Advanced Process
Manager Parameter Reference Dictionary.

10.1 ARRAY POINT OVERVIEW

Array points provide access to two sources of data—

• APM box global variables
• external data from/to Serial Interface devices

In the first case, an Array point can define a section of the box variables as its own data (see
Figure 10-1). Access to single variables over the LCN is limited by the upper index (4095),
but using an Array point you can access upper Flag, Numeric, String, and Time variables.
The Array point can access and fetch string data in lengths of 8, 16, 32, or 64 characters.

APMM
Array
Point

Access to Box Variables in arrays of:

0 - 1023 Booleans (Flags) 0 - 240 ASCII Characters (Strings)
0 - 240 Real Numbers (Numerics) 0 - 240 Times

12446

Figure 10-1 — Array Point Access to Box Global Variables

In the second case, large quantities of data from a Serial Interface (SI) IOP can be scanned
and imaged (read), and used as if it were local data to the Array point (see Figure 10-2).

Writes through the Serial Interface are also permitted. The Serial Interface IOP module is
described in Section 2 of this manual, and its use with an Array point is discussed later in
this section.

APM Control Functions & Algorithms 10-1 12/03

 10.1.1

APM
SI IOP

APMM
(up to 80 SI
Array points)

Power
Adapter

16 Arrays 16 Arrays
To Field FTA FTA To Field
Devices 1 2 Devices

Each Array point can contain up to 512 Booleans (Flags), or 16 Reals (Numerics) or 32
Integers (Numerics), or 64 byte-sized Integers (Numerics), or 64 ASCII Characters (Strings)

Figure 10-2 — Serial Interface to an Array Point

12447

10.1.1 Node Specific Configuration Requirements

Array point configuration begins with APM Node Specific Configuration. You can allocate
up to 256 array points through the parameter NARRSLOT. Other Node Specific
Configuration parameters that affect the Array point are—
• NNUMERIC - the number of Box Numerics (in multiples of 16) that you want
available.

• NSTRING - the number of Box Strings that you want available (in multiples of 16).
Note that Box Strings are only available as 8-character strings.

• NTIME - the number of Box Times (in multiples of 32) that you want available.

APM Control Functions & Algorithms 10-2 12/03

 10.1.2

• SCANPER - if you intend to access Serial Interface data, this parameter specifies
the period at which the APMM scans SI data and maps it to the Array points. The
APMM can scan SI IOP data at three rates and this determines the maximum number
of Array points with SI connections that you can have:

Maximum Number of
SCANPER SI/Array Points
1 Second 80
0.5 Second 40
0.25 Second 20

Finally, you must select SI as the Module Type on the IO Module Configuration pages for
each SI IOP board that you wish to implement.

Note that 16,384 box flags are always available. The number of variables of each particular
global box variable data type available to an Array point is further limited by configuration
parameters for the Array point.

10.1.2 Array Parameter Names

Data elements in the Array point are referred to by the Array point tagname, type of variable
and index number (i). For example ARR01.FL(9). The complete list follows:

Parameter
Variable Reference
Flags FL(i)
Numerics NN(i)
Strings STRn(i)
Times TIME(i)
In the case of strings, n refers to the string length, 8, 16, 32, or 64. For example STR32(4).

APM Control Functions & Algorithms 10-3 12/03

 10.2
10.2 ARRAY POINT USE WITH APM BOX GLOBAL VARIABLES

10.2.1 Configuration

When the External Data Option parameter (EXTDATA) on the Array point configuration
screen form is set to NONE, the Array point parameters provide indirect access to flag,
numeric, string, and time APM box global variables.

Note that an Array point is just a convenient way of referring to related data; the actual data
comes from the APM box global variables (in this case). When accessing one of these
variables by the Array point tag name, the APM translates the request to a specific APM
box global variable.

When accessing the APM box global variables, each Array point allows the following
configuration:

Number of Array Point Range of Range of

Elements Starting Starting Array Size
Index Index
Flags 1–16,384 FLSTIX 1–16,384 0–1023
Numerics 1–NNUMERIC NNSTIX 1 to 0–240
NNUMERIC
Strings 1–NSTRING STRSTIX 1 to 0–240
NSTRING
Times 1–NTIME TIMESTIX 1 to NTIME 0–240

Refer to the APM Parameter Reference Dictionary for a complete description of

the above parameters.

String length—The Array point parameter STRLEN specifies string length as 8, 16, 32, or
64 characters and this determines the format in which strings are presented on the Array
point Detail Display. Regardless of the value of STRLEN, Array point string data can still
be referenced using the STR8, STR16, STR32, or STR64 formats.

Figure 10-3 shows how longer character string lengths can be fetched from the 8-character
format APM box global string variables (provided that the access requested is within the
configured section). For example, if the Array point string starting index is set to 301 and
adequate APM box string variables are configured (in 8-character format), a request for the
64 character Array point parameter STR64(2) will fetch Box.STR8(309) through
Box.STR8(316). If only part of a longer character string can be been fetched, the available
portion is fetched. An array index error results when none of the requested string is
available.

APM Control Functions & Algorithms 10-4 12/03

 10.2.1

STR32(1)

STR16(1) STR16(2)

BOX.STR8(301) BOX.STR8(302) BOX.STR8(303) BOX.STR8(304)

STR64(1)

BOX.STR8(305) BOX.STR8(306) BOX.STR8(307) BOX.STR8(308)

BOX.STR8(309) BOX.STR8(310) BOX.STR8(311) BOX.STR8(312)

STR32(4)
STR64(2)
STR16(7) STR16(8)

BOX.STR8(313) BOX.STR8(314) BOX.STR8(315) BOX.STR8(316)

11395

Figure 10-3 — String Array with Starting Index Set to 301

Descriptors—You can enter 4 descriptors up to 64 characters long, 1 for each type of

variable. These descriptors are typically used to describe the array variables. They appear on
the Array point Detail Display. Refer to the Process Operations Manual for examples.

Access Lock—Parameter SPLOCK determines store access to the variables. Configuration

choices are Operator, Supervisor, Engineer, or Program.

APM Control Functions & Algorithms 10-5 12/03

 10.2.2

10.2.2 Array Point Example

Array point ARR100 is configured to represent the ingredients necessary to make product
X. The parameters are configured as follows:

Parameter Meaning Example Entry

PTDESC point descriptor "Product X ingredients"

FLSTIX flag starting index 0
NFLAG number of flags in array 0
NNSTIX numerics starting index 2001
NNUMERIC number of numerics in array 75
STRLEN string length 16
STRSTIX strings starting index 1001
NSTRING number of strings in array 75
TIMESTIX times starting index 0
NTIME number of times in array 0
SPLOCK set point lock Operator
NNDESC numeric descriptor "Product X Ingredient Amounts"
STRDESC strings descriptor "Product X Ingredient Descriptions"

The 75 numerics list the amounts of all possible ingredients. The 75 strings describe each
ingredient. The descriptor entries (for NNDESC and STRDESC in this case) subsequently
appear on the point Detail Display and describe the ingredients. Refer to the Process
Operations Manual for examples of the Array point Detail Display.

Additional Array points could be configured to store other attributes of each of the 75
ingredients, such as specific gravities, etc.

After loading the Array point, the parameters AR100.STR16(1 to 75) can be used to refer to
the ingredients for Product X. The parameters AR100.NN(1 to 75) can be used to refer to
the amount of each ingredient for Product X.

On the Detail Display, array variables appear in a table numbered from 1 through the end of
the array. Note that by choosing the starting index to end in 1 in the above examples, the
box variables and array variables correspond more conveniently. For example,
ARR100.NN(70) is mapped to box variable NN(2070) and appears on the Detail Display as
N0070.

APM Control Functions & Algorithms 10-6 12/03

 10.3
10.3 SERIAL INTERFACE TO ARRAY POINTS
When the Array point’s EXTDATA parameter is set to IO_FL, IO_NN, or IO_STR (flags,
numerics, or strings, respectively), communications is through the Serial Interface (SI) and
the point is often referred to as an SI Array point. A maximum of 80 Array points can
interface with SI IOP modules depending on the box parameter SCANPER (see subsection
10.1.1).
The Array point accesses external data from the serial device through its Flag, String, and
Numeric parameters. For each Array point, only one type of variable (Strings, Flags, or
Numerics) can be used for Serial Interface communications. Non-selected parameters still
refer to the APM Box variables. For example, if the EXDATA selection is IO_FL, the
number and starting index for flags refers to Serial Interface data through the selected FTA,
while numeric, string, and times references from this array point are to the APM box
variables.
Figure 10-4 illustrates communications between the Array point and the serial IO
subsystem. The plug-in FTA module adapts I/O requirements for the specific serial
interface.
The SI IOP module has 32 slots available. Up to 16 slots can communicate through FTA
number 1, and up to 16 slots can communicate through FTA number 2. An array point
automatically communicates through any available slot on the SI IOP connected to the FTA
specified during Array point configuration. The Serial Input IOP module is described in
Section 2 of this manual and detailed configuration information is provided in the APM
Serial Interface Options manual.
10.3.1 Accessing SI Array Data
Serial Interface IOP data mapped to an Array point is accessed through the Array point
Numeric(NN(i)), Flag (FL(i)), and String (STRn(i)) parameters.
Because the APMM regularly scans data from the Serial Interface, read access to SI Array
data does not require an IOL prefetch cycle (that is, CL programs are not delayed while data
is being fetched). See also 10.3.5.
10.3.2 SI Array Point Configuration
The following paragraphs describe some of the parameters and considerations that are
needed for SI Array point communications. Refer to the APM Serial Interface Options
manual for a detailed explanation.

APM Control Functions & Algorithms 10-7 12/03

 10.3.2
10.3.2.1 External Data Parameters

When the Array point is configured to obtain input from a serial interface (EXTDATA =
IO_FL, IO_NN, or IO_STR), additional parameters appear on the configuration screen
form. These are:
• the SI IOP module number IOPNUM
• the FTA number, 1 or 2 FTANUM
• the serial link device address DEVADDR
• FTA scan priority, low or high SCANPRI

APMM

Box
Variables

SI Image
Array Database
Point

Read
Write

SI IOP

Slots Slots
1–16 17–32

FTA FTA
#1 Serial #2 Serial
Link Link

Plug in Module

Scan
Serial
Subsystem

Serial
Register Subsystem
Range to
be Scanned

Serial
Subsystem

Figure 10-4 — Signal Path Between SI Subsystems and Array Point 11396

APM Control Functions & Algorithms 10-8 12/03

 10.3.2
10.3.2.2 Modbus and Allen-Bradley Interface Parameters

An SI Array point typically interfaces with an AEG Modicon Generic Controller, a Generic
Modbus RTU Controller, or an Allen-Bradley programmable logic controller. Other devices
that use the Modbus RTU protocol may communicate to an SI Array point. Your Honeywell
representative can provide a list of certified devices.

AUXDATA Parameters—These parameters are for use with the Generic Modbus
interface. They should be set to NaN (dashes) when communicating with an Allen-Bradley
PLC. Likewise, when the Modbus interface is being used, the AB_DATA parameters
should be set to NaN.

Parameter Specifies
AUXDATA1 Modbus Coil Keep Alive Address
AUXDATA2 Wait time before message retry
AUXDATA3 EIA protocol and modem control
AUXDATA4 Baud rate and Parity

AB_DATA parameters—These parameters are for use with the Allen-Bradley interface.
They should be set to NaN (dashes) when communicating with a Modbus. Likewise, when
the Allen-Bradley interface is being used, set AUXDATA parameters to NaN.

The following table is only a general overview of the AB_Data parameters. Each is
discussed in detail in the APM Serial Interface Options manual and there are many
variations depending on the PLC family.

Parameter Specifies
AB_DATA1 The PLC family
AB_DATA2 The PLC file number
AB_DATA3 The Data type
AB_DATA4 The Scan rate

10.3.2.3. Array Type/Size and Starting Index

Most of the remaining SI Array parameters considerations deal with a starting index and
array size (number of flags, numerics, or strings).

When used with the Serial Interface, the starting index parameters: FLSTIX (Flag),
NNSTIX (Numeric), or STRSTIX (String) refer to a register address in the serial device.
This register is scanned over the appropriate range as set by the array size.

APM Control Functions & Algorithms 10-9 12/03

 10.3.3
The concept of array type, size, and starting index is the same as described for mapping to
APM box variables, but for Serial Interface data, the limits are as follows:
Array Array Starting Index
Type Size Range
Flag 0 -512 0 - 99,999
Numeric (reals) 0 - 16 0 - 99,999
Numeric (integers) 0 - 32 0 - 99,999
Strings 0 -8* 0 - 99,999
*64 characters maximum configured any way from eight 8-character strings to one
64-character string.

10.3.3 Status and Error Checking

Status reporting—Several Array point parameters are provided for status reporting. Error
information appears on the Array Point Detail displays and the SI IOP Detail Status display,
or can be tested with CL. The following parameters should be checked periodically:
• BADPVFL provides an overall database status (ON = bad). The overall status is bad
when there are communication problems or the SI module is in Idle. When the overall
status is bad, an attempt to access numeric, flag, or string data results in a bad access
status. Consequently, CL programs should check BADPVFL or INITREQ
before using SI data.
• INITREQ, when set to ON, indicates that the write to the SI module cannot be
completed.
• ERRCODE provides an 8-character error string. Refer to the Advanced Process
Manager Parameter Reference Dictionary for complete information.

Note that BADPVFL and INITREQ are always OFF if not using SI data (EXTDATA =
None).

APM Control Functions & Algorithms 10-10 12/03

 10.3.5

10.3.4 Read-Back Check for Device control/Digital Composite Points

Device Control or Digital Composite points can have digital output connections through an
SI/Array point to a field subsystem. The field device or its interface may interrupt or change
the output and not provide any indication of the change.

If flag data is mapped back from the SI/Array point, a digital output read-back check
determines the actual value of the output. After a new output state is stored to the digital
output connections, the read-back check is delayed for a time period equal to the feedback-
time parameter (FBTIME) or 4 seconds, whichever is greater. This delay allows the
SI/Array output enough time to reach even a slow responding field device before causing a
Command Disagree alarm (see subsections 4.5 and 11.5).
If a discrepancy then exists between OPFINAL and OP, the operator is advised. If
OPFINAL does not agree with any of the defined states, its state is displayed as NONE.

10.3.5 CL Notes

All Array point data (flags, numerics, etc.) can be accessed by a CL program (without
impacting IOL prefetch limitations). Refer to the Control Language/Advanced Process
Manager Reference manual for additional information.

The CL/APM compiler issues a warning when external Array point data (data read from a
Serial Interface) is used in a LOCAL declaration. This is done because the data is not truly
local, but resides in the external device connected to the Serial Interface IOP.

APM Control Functions & Algorithms 10-11 12/03

APM Control Functions & Algorithms 10-12 12/03
 11

DEVICE CONTROL POINT

Section 11
This section describes the functions available in the device control point. Definitions of the
parameters mentioned in this section can be found in the Advanced Process Manager Parameter
Reference Dictionary.

11.1 FEATURES
The Device Control (DevCtl) point provides a way to manipulate a device, typically a
motor, and a way to view the strategy through a single point. In addition, this point helps
the operator to graphically trace the source of an interlock condition.
You can allocate up to 160 Device Control points (NDEVSLOT) or combinations of
standard and fast DevCtl (NFASTDEV) points during Node Specific Configuration.
Some of the features of the device control point are as follows:
• Permits a custom logic design (within the strategies provided by the device control
point) of an interlocked motor control strategy.
• Allows configuration of a seal-in circuit function.
• Allows configuration of a state change function.
• Accommodates single- and dual-speed single direction motors, reversible single-speed
motors and motor-operated valves.

11.2 GENERAL DESCRIPTION

Figure 11-1 is a block diagram of the Device Control Point. It can be thought of as a
combination Digital Composite Point, Logic Point, and Regulatory PV Data Acquisition
point. The left side of this drawing provides a concept of the input processing capabilities,
while the right side of the drawing illustrates the output concept.
The following paragraphs briefly describe the Device Control Point, then each part is
explained in detail on the pages that follow.

Digital Composite Section—Two digital inputs, a Local Manual input, and the Digital
Output(s) make up the Digital Composite part of the point as shown in the upper part of
Figure 11-1. All of the properties of the Digital Composite point described in Section 4
apply to this part of the Device Control point.

Logic Section—The left side of Figure 11-1 shows how up to 12 logic inputs are brought
into the point. The gates that follow allow the inputs to be inverted, delayed, compared, etc.
The resulting signals can drive other gates, interlocks, permissives, or output commands.
Two logic outputs can be configured to output most real or logical data from the point.

APM Control Functions & Algorithms 11-1 12/03

 11.2
Regulatory PV Section—An analog input referred to as the secondary variable (SECVAR)
is provided. It is typically used to monitor motor current. You can configure alarms to
indicate when this input exceeds specified limits and you can accumulate statistics on levels
and durations for this input.

Processing order—The DevCtl point processing order should be regarded as: the
regulatory PV section first, then the logic section, and finally the digital composite section.

Input Processing Output Processing

Digital Input Digital Input

#1 Source #1 Status

Digital Input Digital Input

#2 Source #2 Status Digital Output
Destination(s)
Local Manual Local Manual
Source Input
SECVAR Output
Commanded State
Logical Input Logical Output
Output #1
Sources, 1 to 12 Destination(s)
State Command

Permissive
State #1

Interlock
State #1
Alarms
Output #0
State Command

Permissive
State #0

Interlock Override Interlock

State #0 Alarm Descriptor

Secondary Safety Override

Gates, Interlock
Primary 1 and 2
Output #2
Gates, State Command
1 to 4
Permissive Actual Output Last
State #2 Stored to Device

Interlock
State #2

Primary and
Secondary Input
Gates, 1 to 12

Figure 11-1 — Block Diagram of Device Control Point 11397

APM Control Functions & Algorithms 11-2 12/03

 11.3
11.3 INPUT CONNECTIONS

11.3.1 Digital Inputs

Up to two digital inputs connections can be allocated with NODINPTS (number of Digital
Inputs). The input source is defined by DISRC(1) and DISRC(2), which are thereafter
referred to as D1 and D2. The input source(s) can be specified as a tag name.parameter or a
hardware reference address. Allowable sources are—
• Digital Input Points —PV • Logic Slot Flags
• Digital Output Points —SO • ProcMod Flags
• Logic Slot gate outputs • DevCtl Flags
• PM Box Flags —PV • Array Point Flags
These sources must be in the same APM box as the Device Control point. The PV state is
calculated from the inputs the same way as for a Digital Composite Point.
Other configuration for this section such as box color, etc. is the same as for a Digital
Composite Point as described in Section 4. You can specify the PV states, options, and
alarming.

11.3.2 Logic Inputs

Figure 11-2 presents a simpler way of looking at just the Logic Inputs, their associated
gates, how the outputs can be routed, and possible destinations.
Looking at the logic gates in Figure 11-2, you should note the concept of Primary or
Secondary Input Gates and Primary or Secondary gates. This terminology is used
throughout the following discussions and on the point configuration screens.

LOGIC INPUTS INTERLOCKS,

PERMISSIVES,
PRIMARY SECONDARY AND
LISRC(1) INPUT INPUT COMMANDS
GATE GATE
1 1
2 2 PRIMARY OPCMD
3 • 3 GATES
• SOCMD (0)
• PG1
SOCMD (1)
• PG2
SOCMD (2)
• PG3
• PG4
SECONDARY SI0
PRIMARY • SECONDARY
LISRC(12) • GATES
INPUT INPUT
• I0, I1, I2
GATE GATE SG1
12 12 SG2
P0, P1, P2

Figure 11-2 — Logic Gates and Destinations 11398

APM Control Functions & Algorithms 11-3 12/03

 11.3.2
You can designate up to 12 Logical inputs (NOLINPTS) and enter an 8-character ASCII
descriptor for each input (LIDESC(n) where n is 1–12). The ASCII descriptor can be
changed by a CL program or a person with Engineer access level.
Each input source is specified by Logic input source parameter LISRC(n) and you can
use—
· any boolean, integer, enumeration, self-defining enumeration, or real parameter
from within the APM, or another UCN node
· the PV flag or BADPVFL for a Digital Input point from within the APM
· the SO or INITREQ parameters for a Digital Output point from within the APM
· any IOP parameter (up to a maximum of six).
Logic inputs (LISRC(1) – LISRC(12) are referenced within the configuration pages as
L1 – L12.
The parameter LIBADOPT allows substitution of Off, On, or the last good value (Hold) in
case a logic input goes bad.

NOTE
Every logic input that you specify must eventually be used to drive some output,
permissive, or interlock.

11.3.2.1 Primary and Secondary Logic Input Gates

Algorithms—Figure 11-3 shows the various choices for the Primary Input Gate algorithm
(parameter PIALGID(n)) and the Secondary Input Gate algorithm (parameter SIALGID(n)).
The choices are discussed in the following paragraphs.
Primary Input Gate Algorithms—
Null means the input is passed unchanged to the output.
Comparison algorithms for the Primary Input Gate such as GT, GE, etc compare the
input to parameter PINN(n) where n is the gate number. PINN(n) contains a real number
entry of your choice.
Algorithms ending in 2 such as GT2, GE2, etc., compare the input to a primary input
source specified by PISRC(n) where n is the gate number. This allows you to compare
the configured input to one of the logic inputs (L1 – L12). Gate(n) output goes true
when the comparison succeeds.
In_Set algorithm compares the gate input with a table of ten numerics (NNINSET(n))
and the output goes true if the input equals any value in the set. You must enter the ten
numeric values which can range from 0 to 32,767.

APM Control Functions & Algorithms 11-4 12/03

 11.3.2
Primary Input gates that use comparison algorithms can have a deadband value
(PIDEADBD(n) for each gate—
For GT, GT2, GE, GE2, LT, LT2, LE, or LE2 gates, the deadband only applies on a true
to false comparison. For example, assume that one of these gates is configured
for L1 (input) greater than 50 and the deadband value = 5. The gate output goes true
when L1 is greater than 50, but does not go false unless L1 falls below 45.

For EQ, EQ2, NE, and NE2 gates, the deadband value defines the range of comparison.
For example, an EQ gate is configured with input numeric PINN(n) = 6 and deadband
parameter PIDEADBD(n) =2. The output is true when the input source is between 4 and 8.

Primary Secondary
L(n) Input Gate Input Gate SIDSTN(n)
1 –12 1 –12

PIALGID(n) SIALGID(n)
11399

(Algorithms) (Algorithms)
NULL NULL
INVERT DLY - Delay
GT - Greater than PINN(n) ONDLY - On Delay
GE - Greater than or equal to PINN(n) OFFDLY - Off Delay
LT - Less than PINN(n) PULSE
LE - Less than or equal to PINN(n) MAXPULSE
EQ - Equal to PINN(n) MINPULSE
NE - Not equal to PINN(n)
GT2 - Greater than PISRC(n)
GE2 - Greater than or equal PISRC(n)
LT2 - Less than PISRC(n)
LE2- Less than or equal PISRC(n)
EQ2 - Equal to PISRC(n)
NE2 - Not equal to PISRC(n)
IN_SET
Figure 11-3 — Primary and Secondary Logic Input Gate Algorithms

Secondary Input Gate Algorithms—These include various types of delays. Your entry
(0 – 8000 seconds) in parameter SIDLYTIM(n) determines the delay (per gate). These
functions are briefly described here and fully in the Logic Point description (Section 5).

Delay—The Delay algorithm causes a one cycle delay of the input value (at the
execution rate of the point). Parameter SIDLTYM does not apply to this gate.
On Delay—On Delay starts counting when the input switches from Off to On. If the
input is still On when the time runs out, the output is set to On. When the input signal
switches Off, the output is set to Off immediately and the timer (if running) is stopped.

APM Control Functions & Algorithms 11-5 12/03

 11.3.2
Off Delay —Off Delay starts counting when the input switches from On to Off. If the
input is still Off when the timer runs out, the output is set to Off. When the input signal
switches On, the output is set to On immediately and the timer (if running) is stopped.
PULSE —Pulse provides a fixed pulse output when the input switches from Off to On.
The pulse width is specified by SIDLYTIM(n). Another output pulse cannot be
generated until the preceding pulse has completed.

• MAXPULSE—MAXPULSE provides a pulse output when the input switches from

Off to On. If the input switches Off before the specified time, the output is also set to
Off immediately. If the input stays On longer than the timer period, the output pulse
shuts Off at the end of the timer period.
• MINPULSE—MINPULSE provides a pulse output when the input switches from
Off to On. If the input switches Off before the specified timer period, the output is
extended until the period is over. If the input stays On longer than the timer period,
the output pulse follows the input pulse.

Secondary Input Gate Destinations—the output destination from each Secondary Input
Gate is specified by SIDSTN(n). The choices are shown in Figure 11-4.

Secondary
Input Gate SIDSTN(n)
1–12
(Destination)
11400

• None (gate not used)

• Interlocks SI0, I0, I1, or I2
• Permissive Interlocks P0, P1, or P2
• OPCMD, SOCMD0, SOCMD1, or SOCMD2
• Primary Gates PG1, PG2, PG3, or PG4.
• Secondary Gates SG1 or SG2

Figure 11-4 — Secondary Input Gate Destination Choices

NOTE
Every Secondary Input Gate that you configure must have an output destination specified.

11.3.2.2 Primary and Secondary Logic Gates

You can configure up to four Primary Gates (NOPGATE) and up to two Secondary Gates
(NOSGATE). Each gate can have up to six inputs. The inputs are determined by specifying
them as destinations from other gates. It isn’t necessary to use these gates if you do not need
the functions they provide.

APM Control Functions & Algorithms 11-6 12/03

 11.3.2
Figure 11-5 illustrates the Primary and Secondary Gate algorithm choices.

Primary Gate Inputs—Inputs to the Primary Gates can only come from Secondary Input
Gates. Up to six inputs are available.
Secondary Gate Inputs—Inputs to the Secondary Gates can come from any of the 12
Secondary Input Gates or any of the four Primary Gates.
Primary and Secondary Gate Algorithms—both the Primary and Secondary Gates have
identical algorithms. Algorithms beginning with a P have a pulsed output when the gate is
enabled. Pulse width is specified by parameter PGPLSWTH(n) for Primary Gates or
SGPLSWTH(n) for Secondary Gates. Pulse width can range from 0–8000 seconds.

Primary Secondary
Gate PGDSTN(n) Gate SGDSTN(n)
1–4 1– 2

PGALGID(n) SGALGID(n) 11401

(algorithms) (algorithms)
AND PAND AND PAND
OR POR OR POR
NAND PNAND NAND PNAND
NOR PNOR NOR PNOR
XOR PXOR XOR PXOR
Figure 11-5 — Primary and Secondary Logic Gate Algorithms

Primary Gate Destinations—Parameter PGDSTN(n) directs outputs from Primary Gate n

to any one of the destinations shown in Figure 11-6.

Primary
Gate PGDSTN(n)
1–4
(Destination)
11402

• None (gate is unused)

• Interlocks SI0, I0, I1, or I2
• Permissive Interlocks P0, P1, or P2
• OPCMD, SOCMD0, SOCMD1, or SOCMD2
• Secondary Gates SG1 or SG2

Figure 11-6 — Primary Gate Destinations

APM Control Functions & Algorithms 11-7 12/03

 11.3.2

NOTE
Every Primary and Secondary Gate that you configure must have an output destination
specified.

Secondary Gate Destinations—Parameter SGDSTN(n) directs outputs from Secondary

Gate n to any one of the destinations shown in Figure 11-7.

Secondary
Gate SGDSTN(n)
1–2
(Destination) 11403

• None (gate is unused)

• Interlocks SI0, I0, I1, or I2
• Permissive Interlocks P0, P1, or P2
• OPCMD
• SOCMD0, SOCMD1, OR SOCMD2

Figure 11-7 — Secondary Gate Destinations

11.3.2.3 Detail Display Presentation

A graphic representation of the logic connections is presented on the point’s detail display.
Figure 11-8 is typical of the Override Interlock section of this display. The Logic Input
descriptors you choose (LIDESC(n)) appear instead of the numbered inputs shown in the
example. Heavy lines indicate power flow and allow the operator to determine which input
is driving an interlock such as shown in Figure 11-8 where Input _7 is driving the override
interlock. Refer to the Process Operations Manual for additional information.

OVERRIDE
STOP
AND OR
Input_4
2 3

Input_5

Input_6

Input_7
11404

Figure 11-8 — Detail Display of Logic Configuration

APM Control Functions & Algorithms 11-8 12/03

 11.3.3

11.3.3 Secondary Variable Input

This Regulatory PV section of the DevCtl point provides an analog input for a Secondary
Variable (SECVAR). The Secondary Variable input connection is specified by parameter
SVSRC as a tag name.parameter or hardware address reference. Typically this input is used
to monitor motor current, flow rate, valve position, etc.
During configuration you can specify
• descriptors–(SVDESC and SVEUDESC)
• the high/low engineering unit range–(SVEUHI/SVEULO)
• the target value (setpoint)–(SVTV)
• the high and high high trip point–(SVHITP and SVHHTP)

You can also specify the alarm priorities, an alarm deadband, and the secondary variable
alarm mask time. Mask time (MASKTIM) specifies the time from 1–1000 seconds that
alarms are inhibited after an output change.

Several historical items related to the Secondary Variable can be accumulated and reported
on the Maintenance Statistics Display section of the point’s Detail Display. These are—
• the peak value of the secondary variable on the last run.
• the duration of the first peak above the full load high trip limit.
• the time that the secondary variable is continuously greater than its high trip limit.

Subsection 11.6 describes the maintenance statistics in more detail.

APM Control Functions & Algorithms 11-9 12/03

 11.3.3
Figure 11-9 shows how the Secondary Variable appears on the point detail display. The
thick bar represents the actual value. The lower vertical dash represents the target value
(SVTV). The Secondary Variable high alarm priority trip point in percent (SVHITPP) and
high high alarm trip point in percent (SVHHTPP) are represented by the other two small
vertical dashes.

SVHITPP SVHHTPP

SVTV
11405
11405b

Figure 11-9 — Secondary Variable Representation on the Point Detail Display

The colors of SVHITPP and SVHHTPP are described in Table 11-1.

Table 11-1 — SVHITP and SVHHTP Colors

Network Config. Red
Color Alarm Priority SVHITP Color SVHHTP Color
Two Alarm SVHIPR = SVHHPR =
Colors Low Hi Emg. Low Hi Emg.

Low Red Red Red Red Red Red

High Yel Red Red Yel Red Red
Emergency Yel Yel Red Yel Yel Red

Three Selectable Depends on color Depends on color

Alarm Colors selected in NCF selected in NCF

When SVHITPP is configured = SVHHTPP, a single vertical dash represents both values.
Its color is determined in the same way as for SVHHTPP.

The Red Color Alarm Priority is configured during the Console Data part of Network
Configuration.

APM Control Functions & Algorithms 11-10 12/03

 11.3.3

The bar graph color for the Secondary Variable in percent (SVP) depends on the Secondary
Variable High alarm Flag, the High High alarm Flag, and the Secondary Variable High and
High High alarm priorities.

If the two-color alarm option is selected in the Network Configuration File (NCF), SVP
color is described in Table 11-2.

Table 11-2 — SVP Bar Graph Color

Condition Result
1 If SVHIFL and SVHHFL are both FALSE SVP color is Cyan
2 If SVHIFL is TRUE, then the following table determines
when SVP color is RED.
Network Configuration SVHIPR =
Red Color Alarm Priority = Low Hi Emg.
Low Red Red Red
High N/A Red Red
Emergency N/A N/A Red
3 If SVHHFL is TRUE, then the following table determines
when SVP color is RED.
Network Configuration SVHHPR =
Red Color Alarm Priority = Low Hi Emg.
Low Red Red Red
High N/A Red Red
Emergency N/A N/A Red
4 For all other conditions SVP color is Yellow

If the three color alarm option was selected in the NCF, the SVP color is based on the color
choices in the NCF.

If the three color alarm option was selected in the NCF, the SVP color is based on the color
choices in the NCF.

11.3.4 Local Manual Input

Parameter LMSRC allows you to designate a logical input for the local manual signal. The
source can be specified as a tag name.parameter or as a hardware reference address.
Parameter LMREV permits the input to be inverted.

When the LOCALMAN flag is true, it indicates that the device’s state is being controlled
directly by external hardware. The Device Control point’s output tracks the PV (the actual
state of the device). When the device is taken out of Local/Manual, the output of the point
matches the current state of the device being controlled.

APM Control Functions & Algorithms 11-11 12/03

 11.4
11.4 OUTPUT CONNECTIONS

11.4.1 Digital Outputs

The number of digital outputs (up to three) is determined by parameter NODOPTS. State
Outputs destinations for STxOPy (where x = 0, 1, 2 and y = 1, 2, 3) are assigned by
parameter DODSTN(n) where n = 1–3 (depending on the number of outputs configured).
Acceptable destinations are—
• Digital Output Point–Latched Output • Digital Output Point–Pulsed Output
• Logic Slot Flag • APM Box Flag
• Process Module Slot Flag • Device Control Slot Flag
• Array Point Flag (see also 10.3.4)
Destinations are specified as a tag name.parameter or a hardware address and they must be
in the same APM as the Device Control point. If a hardware address is used, it must have
one of the following forms—
• !BOX.FL(nnnn) where nnnn = 1 to 16,384
• !DOmmSss.S0
11.4.1.1 Output Commands

There are two ways to command the output:

• when MODATTR = Operator, the operator can command it
• when MODATTR = Program, a Logic point or CL program can command it
OPCMD controls State 0 and State 1. SOCMD(n) controls State 0, State 1, and State 2.
Inputs to OPCMD or SOCMD can come from any of the following logic gates:
• the Primary Gates
• the Secondary Gates
• the Secondary Input Gates
Inputs to OPCMD or SOCMD are made by specifying them as destinations of the above
logic gates. Both OPCMD or SOCMD can be configured to drive the output, but you should
use only one of these on a given point. When interlock logic does not drive OPCMD or
SOCMD, they can be written from outside (for example from a Logic point, a CL Program,
etc.)

CAUTION
Do not configure two different logic outputs to drive OPCMD and SOCMD of the same Device
Control Point.

APM Control Functions & Algorithms 11-12 12/03

 11.4.1
The state of OP is calculated from signals generated by the primary and secondary gates
through OPCMD or SOCMD, as well as LOCALMAN and REDTAG.
OP can be commanded to state 1 or state 0 using the OPCMD parameter. When OPCMD is
commanded ON, OP is set to state 1. When OPCMD is commanded OFF, OP is set to State
0. OPCMD can be used when three states are defined, but will only command OP to state 1
or state 0.
SOCMD(i) provides a command for each state (i = 0, 1, or 2). Unlike OPCMD, the output
state is commanded when SOCMD(i) goes from OFF to ON. For example, if SOCMD(1) is
commanded ON, State 1 goes true. Then if SOCMD(0) is commanded ON, State 0 is
commanded. It does not matter that the logic for SOCMD(1) is still commanding an ON
condition. In order to return to State 1, SOCMD(1) must command an OFF, and then an ON
condition.

11.4.1.2 Interlocks, Permissives, and Overrides

The ON command is sent to the output only if the permissives and interlocks are in a state
to permit the output. If the ON state is allowed, ON becomes the Output Final OPFINAL
output. OP and OPFINAL may be different; for example, if the seal in option is activated.
Seal-in —If the seal-in circuit is configured, it will unlatch the digital output contacts on
detection of the PV not following the output command as happens on a device drop out (for
example, a stopped motor). This condition is true any time the PV is not in state 1 or state 2
and either a command disagree alarm or an uncommanded state change alarm is present.
If the seal in option is enabled when the above condition is detected, the output destinations
are set to the state corresponding to OP of state 0, but OP is not altered. The actual state
commanded to the output destinations can be observed on the lower part of the group
display as OPFINAL. OPFINAL appears in reverse video when not equal to OP.
Figure 11-10 illustrates the interlock system associated with the Device Control Point’s
digital outputs. This illustration is described thoroughly in Section 4 for the Digital
Composite point and is reproduced here for convenience.
Inputs—Inputs to the interlocks can come from the output of —
• any of the Secondary Input Gates
• any of the Primary Gates
• either of the Secondary Gates.
Inputs to the interlocks can also be written to from outside if not driven by any interlock
logic (like OPCMD and SOCMD(n). Parameter LOGICSRC allows you to enter the name
of an external point (if any) that is controlling interlocks and permissives. The entry then
appears on the Detail Display.
Break Before Make Option—When OP is commanded from State 1 to State 2 (for
example, from forward to reverse), or from State 2 to State 1, OP will first go to State 0 (for
example, stop) and remain there for a configured pause time before going to the
commanded state.

APM Control Functions & Algorithms 11-13 12/03

 11.4.1

Operator
Commanded State Off
(OP) from Operator Off

On On
Commanded State NMODATTR OROPT BYPASS
(OP) from Program Program

Commanded
STATE 2 State STATE 1

STATE 0
Permissive
Interlocks ON ON ON
(P1, P0, & P2 are OFF P2 OFF P0 OFF P1
controlled by
Logic Blocks)

STATE 2 STATE 0 STATE 1

ON OFF
STATE 2 I2
Override
Interlocks
(I2, I1, & I0 are
controlled by ON OFF
Logic Blocks) STATE 1 I1

ON OFF
STATE 0 I0

OFF
Safety ON
Interlock SI0
STATE 0

Output Connections
(Up to 3 Outputs)
PULSEWTH OUTPUT STxOPy
STCHGOPT STATE
STxOPy
SEALOPT GENERATOR
MOMSTATE (OPFINAL) STxOPy
x = 0, 1, 2
y = 1, 2, 3
Figure 11-10 — Interlocks and Permissive 2100

APM Control Functions & Algorithms 11-14 12/03

 11.4.1
11.4.1.3 Digital Outputs on the Detail Display

Figure 11-11 shows how the commanded digital output appears on the detail display for a
two state and for a three state output.

The right half of any state box (when filled) indicates the commanded state. The left half of
any state box (when filled) indicates the PV has changed to that state.

Two dashes in a state box means that operator commands for that state are not permitted.
This can be caused because an interlock is active, when a program is controlling the point,
or the permissive for the state is OFF.

START FORWARD

STOP OFF

REVERSE

11406
11406

Figure 11-11 — Output Indicators on the Point Detail Display

11.4.2 Logic Output Connections

The Device Control point can have up to two (NOLOPTS) Logic Output connections.
Figure 11-12 illustrates the Logic Output connection strategy. LOSRC is the logic source,
LOENBL is the flag that enables the gate, and LODSTN is the output destination.

LOSRC(n) Out
LODSTN(N)
LOENBL(n) Enable
11407

Figure 11-12 — Logic Output Connections

APM Control Functions & Algorithms 11-15 12/03

 11.4.2

LOSRC(n), the logic source can come from—

L1–L12 the logic inputs
FL1–F12 the local flags (you can set FL7–FL12 Off or On)
NN1–NN8 the local numerics (you can enter the values)
D1 or D2 the digital inputs
P0, P1, or P2 permissive interlocks
SI0, I0, I1, or I2 Safety and other Status Overrides
PISO1–PISO12 Primary Input Gate output value
SISO1–SISO12 Secondary Input Gate status output
PGSO1–PGSO4 Primary Gate status output
SGSO1–SGSO2 Secondary Gate status output
PINN1–PINN12 Primary input comparison numerics
SECVAR the secondary variable

LOENBL(n), the output enable signal can come from—

L1–L12 the logic inputs

FL1–F12 the local flags
D1 or D2 the digital inputs
P0, P1, or P2 permissive interlocks
SI0, I0, I1, or I2 Safety and other Interlock Overrides
PIS01–PISO12 Primary Input Gate output value
SISO1–SISO12 Secondary Input Gate status output
PGSO1–PGSO4 Primary Gate status output
SGSO1–SGSO2 Secondary Gate status output

LODSTN(n), the destination point.parameter to which the output is pushed can be either an
ASCII tag name or the hardware address of a point. The destination parameter can be any
type parameter (a conversion is made internally to write the correct data type to the
destination). If a hardware address is used it must be of the form !BOX, !AOmmSss, or
!DOmmSss, where mm is an Analog output or Digital Output IOP module number and ss is
the slot number within that module.

APM Control Functions & Algorithms 11-16 12/03

 11.5

11.5 ALARMS

The Device Control Point provides the following alarms:

BADPVFL, Bad process variable alarm
BADSVFL, Bad secondary variable alarm
CMDDISFL, Command disagree alarm
CMDFALFL, Command fail alarm
OFFNRMFL, PV off normal state alarm
OVRDI0FL, OVRDI1FL, OVRDI2FL, Override interlock alarms
OVRDSIFL, Safety Override alarm flag
SVHHFL, Secondary variable high high alarm
SVHIFL, Secondary variable high alarm
UNCMDFL, Uncommanded state alarm

BADPVFL indicates that a digital input has detected a bad PV value.

CMDDISFL, the command disagree flag indicates that the field device did not go to the
commanded state within the allowed time.

CMDFALFL, the command fail alarm (also called the crack timer) is generated if the PV
doesn’t change within the time specified by the command fail timeout parameter
(CMDFALTM) after the OP is commanded to a new state. This alarm is useful for motor
driven valves with states of OPEN, INBETWEN, and CLOSED. Alarm priority for the
command fail alarm is determined by the Command Disagree Priority (CMDDISPR)
parameter.

OFFNRMFL indicates that an Off Normal alarm has been detected.

The Secondary Variable high and high high alarms indicate the analog input SECVAR has
exceeded the configured limits and BADSVFL indicates the input value is NaN.

UNCMDFL, the uncommanded state alarm indicates that a field device changed state
without being command to do so.

The override interlock alarms and the safety override alarm indicate that an override is
active. Also refer to the Override descriptor description below.

Override Interlock Alarm Descriptor—When an interlock is tripped, the Device Control

point traces the cause of the interrupt and presents the logic descriptor LIDESC(n) for that
input on the Detail Display just above the MAN/P-MAN indicator.

APM Control Functions & Algorithms 11-17 12/03

 11.6

11.6 MAINTENANCE STATISTICS

If the Maintenance Support Option is enabled (MAINTOPT = ON), various maintenance

statistics are calculated and displayed on the maintenance page of the point’s Detail
Display. These statistics are available as standard parameters so they can be accessed by CL
programs, schematics, etc., and can be saved on a history module.

A program can reset the maintenance statistics at any time by setting the point’s reset flag
parameter (RESETFL) to ON. The operator can only reset the statistics when the point is in
REDTAG.

During configuration, you can enter a maximum time allowed. The parameter
MAXTIMnH, n = 0, 1 or 2 sets the maximum time in hours. The maximum number of
transitions allowed into each state since the last reset is configured with parameter
MAXTRANn (where n = 0, 1 or 2). There is no alarming if the values are exceeded, but CL
programs can compare maximum specified values with accumulated values.

The Maintenance Statistics are presented in a plain english format. In addition, the display
contains a REDTAG target.

If you select the REDTAG target and press ENTER, the point’s REDTAG parameter is set
to ON and a RESET target appears. Selecting the RESET target (and pressing ENTER)
resets the points maintenance statistic values. If you select REDTAG, (and press ENTER)
the REDTAG condition clears and the RESET target disappears.

APM Control Functions & Algorithms 11-18 12/03

 Index
Topic Section Heading

Accumulation, Digital Input 2.5.3

Accumulator Commands 2.5.3.2
Overflow 2.5.3.4
Target Value 2.5.3.3
Up/Down Accumulation 2.5.3.1
Alarms, General
Cut Out 1.3.3
Enabling, Disabling, and Inhibiting 1.3.2
Priorities 1.3.1
Primmod points 1.3.4
Regulatory Control Output High/Low Alarms 8.10.7
Algorithms
Auto Manual (AUTOMAN) 8.14.8
Calculator (CALCULTR) 7.7.9
Data Acquisition (DATACQ) 7.7.1
Flow Compensation (FLOWCOMP) 7.7.2
General Linearization (GENLIN) 7.7.8
High Selector, Low Selector, Average (HILOAVG) 7.7.4
Incremental Summer (INCRSUM) 8.14.9
Middle of Three Selector (MIDOF3) 7.7.3
Override Selector (ORSEL) 8.14.11
PID with External Reset -Feedback (PIDERFB) 8.14.3
PID with Feedforward (PIDFF) 8.14.2
Proportional, Integral, Derivative (PID) 8.14.1
Ramp and Soak (RAMPSOAK) 8.14.7
Ratio Control (RATIOCTL) 8.14.6
Summer (SUMMER) 7.7.5
Switch (SWITCH) 8.14.10
Totalizer (TOTALIZR) 7.7.7
Variable Dead Time with Lead-Lag Com (VDTLDLG) 7.7.6
Allen-Bradley PLC Interface Through SI Array Point 10.3
Report By Exception 10.3.5.5
Diagnostic Procedures 10.3.5.7
Analog Inputs, High Level and Low Level 2.2
Alarming 2.2.4
Overview 2.1
PV Characterization 2.2.1
Characterization Options Table 2-1
Linear Conversion 2.2.1.1
Sensor Types Table 2-1
Square-Root Conversion 2.2.1.2
Thermal Conversion 2.2.1.3
PV Range Checking and Filtering 2.2.2
PV Source Selection 2.2.3
Analog Inputs, Smart Transmitter Interface 2.3
Alarming 2.3.2.7
Commands 2.3.6
Communication Modes 2.3.3
Considerations 2.3.4
Correcting Database Mismatches 2.3.4
Component Point Usage Example Figure 1-2

APM Control Functions & Algorithms Index-1 12/03

 Index
Topic Section Heading

Database Considerations, STI 2.3.4

Database Mismatches, STI 2.3.4
Detail Display Figure 2-2
Functions 2.3.2
Number of Points Per STI Card 1.1.1
Parameter Comparisons 2.3.1
Point States 2.3.5
PV Characterization 2.3.2.1
PV Characterization Options Table 2-3
Linear 2.3.2.2
Square Root 2.3.2.3
Thermal 2.3.2.4
PV Range Checking and Filtering 2.3.2.5
PV Source Selection 2.3.2.6
Smart Field Communicator 2.3, 2.3.4
Status,
STI 2.3.5
Transmitter 2.3.4
Transmitter Types Supported 2.3
Use of Damping vs. TF 2.3.2.5
Valid Damping Values 2.3.2.5
Analog Outputs 2.4
Calibration Compensation 2.4.3
Direct/Reverse Output 2.4.1
Output Characterization 2.4.2
Associated Display 1.2.2
Array Points 10
Node Specific Configuration Requirements 10.1.1
Array Parameter Names 10.1.2
Array Point Use with APM Box Global Variables 10.2
Array Point Example 10.2.2
Serial Interface to Array Point 10.3
Status and Error Checking 10.3.3
Modbus and Allen-Bradley PLC Interface parameters 10.3.2.2
Read-Back Checks 10.3.4
CL Notes 10.3.5
Auto Manual Station — see also Manual/Auto Station
Auto Manual (AUTOMAN) Control Algorithm 8.14.8
Bumpless Returns to Cascade Operation 8.14.8.3.1
Engineering Unit Ranges 8.14.8.3.4
Equations 8.14.8.4
Error Handling 8.14.8.3.6
Function 8.14.8.1
Functional Diagram Figure 8-23
Initialization 8.14.8.5
Modes, Operating 8.14.8.3.2
Options and Special Features 8.14.8.3
Override Feedback Processing 8.14.8.6
Diagram of Figure 8-25
Restart or Point Activation 8.14.8.3.5
Use 8.14.8.2
Auxilliary Units 1.3.5
Bad PV/Mode Shed 8.4.4.4
Bias Option 8.7.6

APM Control Functions & Algorithms Index-2 12/03

 Index
Topic Section Heading

Box, APM
Alarm Enable Status 1.3.2
Alarm Priorities 1.3.1
Alarming 1.3
AO Data Point 2.4
Box Flag Data Point 9.2
Box Numeric Data Point 9.3
Box Timer Data Point 9.4
Common Functions 1.2
Control Functions 1.1.2, Section 3
Control Performance 3.1
Database Considerations 3.2
Determining Processing Capacity 3.1.3
DI Data Point 2.5
Dig Comp Data Point Section 4
DO Data Point 2.6
Flag Data Point 9.2
Global Variables 9.1
Hardware Reference Addressing 3.5
HLAI Data Point 2.2
I/O Functions 1.1.1, Section 2
LLAI Data Point 2.2
LLMUX Data Point 2.2
Logic Slot Section 5
Numeric, Box Data Point 9.3
Peer-to-Peer Communication 3.4
Point Execution State 3.3
Process Module Data Point 6.1
Pulse Input Data Point 2.7
Red Tagging 1.4
RegCtl Data Point Section 8
RegPV Data Point Section 7
RHMUX Data Point 2.2
Scan Frequency 3.1.2
Scan Rate 3.1.2.1
STI Data Point 2.3
Time Variables 9.5
Timer, Box Data Point 9.4
Calculator Algorithm 7.7.9
Arithmetic Functions 7.7.9.1
Assignment Statement 7.7.9.1
Equation 7.7.9.4
Error Handing of Bad-Inputs and Uncertain Values 7.7.9.3
Function 7.7.9.1
Functional Diagram Figure 7-13
Operators 7.7.9.1
Options and Special Features 7.7.9.3
Separator 7.7.9.1
Use 7.7.9.1

APM Control Functions & Algorithms Index-3 12/03

 Index
Topic Section Heading

CALCULTR 7.7.9
Changing Dead Time (Delay-Time) Parameters (see also
Variable Dead Time with Lead Lag) 7.7.6.3
Characterization (HLAI, LLAI, LLMUX, and RHMUX)
Input (PV) 2.2.1
Linear Conversion 2.2.1.1
Range Checking and Filtering 2.2.2
Source Selection 2.2.3
Square Root 2.2.1.2
Thermal (RTD and Thermocouple) 2.2.1.3
Characterization (STI)
Input (PV) 2.3.2.1
Linear Conversion 2.3.2.2
Range Checking and Filtering 2.3.2.5
Source Selection 2.3.2.6
Square Root 2.3.2.3
Thermal (RTD and Thermocouple) 2.3.2.4
CL/APM Sequence Program 6.1.1
Cold/Warm Restart 3.3.2
Command Disagree Alarm 4.5, 4.14, 11.4.1, 11.5
Communications, Peer-to-Peer 3.4
Connections
Hardware Reference Addressing 3.5
Input Connections
To Digital Composite 4.11
From Digital Input PV 4.11.1
From Logic Slot Output 4.11.2
From Logic Slot Flag 4.11.3
From APM Box PV Flag 4.11.4
To Logic Slot 5.2.1
To Regulatory PV Data Point 7.2
To Regulatory Control Point 8.2
Output Connections
From Digital Composite
Latched 4.7.1
Pulsed 4.7.2
To Logic Slot Flag 4.7.3
To APM Box PV Flag 4.7.4
From Logic Slot 5.2.5
From Regulatory Control Slot 8.9.6
Contact Cutout 1.3.3
Control Algorithms 8.14
Control Functions — see Control Slots
Control Language — See "Process Module Data Point"
Control Slots
Connections — see "Connections"
Determining Processing Capacity 3.1.3
Digital Composite 4.1
Functions 1.1.2
Logic Slot 5.1
Overruns 3.1.3.1

APM Control Functions & Algorithms Index-4 12/03

 Index
Topic Section Heading

Overview 3.1
Peer-to-Peer Communication 3.4
Point Form 1.2.1
Regulatory Control 8.1
Regulatory PV 7.1
Scan Rates 3.1.2
Types 3.1.1
Data Acquisition Algorithm (DATACQ) PV Algorithm 7.7.1
Function 7.7.1.1
Functional Diagram of Figure 7-2
Equations (forms of) 7.7.1.4
Options and Special Features 7.7.1.3
Use 7.7.1.2
DATACQ 7.7.1
Dead-Time (Delay-Time) Calculation (see also Variable
Dead Time with Lead Lag) 7.7.6.3
DEVICE CONTROL POINT 11, 3.1.1
Input Connections 11.3
Digital Inputs 11.3.1
Logic Inputs 11.3.2
Secondary Variable Input 11.3.3
Local Manual Input 11.3.4
Output Connections 11.4
Digital Outputs 11.4.1
Logic Output Connections 11.4.2
Read-Back Check 10.3.4
Alarms 11.5
Maintenance Statistics 11.6
Device Reservation 3.7
Digital Composite — see Section 4
Alarms 4.14
Command Disagree 4.14.1
Off-Normal 4.14.2
Uncommanded Change 4.14.1
Array Point Flags 4.7.6, 4.11.6
Change-Of-State Events 4.15
Commanded State 4.5
Connections
Input 4.11
Output 4.7
Configuring the Input State 4.12
Device Control Point Flags 4.7.5, 4.11.5
Initialization Manual 4.9
Inputs 4.10
Interlocks 4.4
Latched Output 4.6.1
Local Manual Indication 4.16
Maintenance Statistics 4.17
Reset/Redtag 4.17.1
Mode Attributes 4.3
Momentary States 4.2.2

APM Control Functions & Algorithms Index-5 12/03

 Index
Topic Section Heading

Moving/Bad States 4.2.3

Normal States 4.2.1
Outputs 4.6
Override Interlocks 4.4.2
Permissive Interlocks 4.4.1
Pulsed Output 4.6.2
PV Source 4.13
Read-Back Check 4.8
States 4.2
Digital Input
Accumulation Digital Input 2.5.3
Accumulator Commands 2.5.3.2
Overflow 2.5.3.4
Target Value 2.5.3.3
Up/Down Accumulation 2.5.3.1
Latched Digital Input Point 2.5.2
Event Reporting 2.5.2.1
Status Digital Input 2.5.1
Event Reporting 2.5.1.3
Off-Normal Alarming 2.5.1.2
PV Source Selection 2.5.1.1
Digital Output 2.6
Pulse Width Modulated Output Type 2.6.1
Status Output Type 2.6.2
External Mode Switching 8.6
Fast Slots 3.1.2.2
Field Inputs
see "Inputs, Field" or "Analog Input" or "Digital Input"
Field Outputs
see "Outputs, Field" or "Analog Output " or "Digital Output"
Fixed Delay Time (see also Variable Dead Time with Lead Lag) 7.7.6.3
Flags
Logic Point 5.2.2
APM Box 9.2
Alarming 9.2.1
Process Module 6.1.3.2
FLOWCOMP 7.7.2
Flow Compensation PV Algorithm (FLOWCOMP) 7.7.2
Compensating for Assumed Design Conditions 7.7.2.3
Equations (forms of) 7.7.2.4
Error Handling 7.7.2.3
Function 7.7.2.1
Options and Special Features 7.7.2.3
Parameters 7.7.2.4
Restart or Point Activation 7.7.2.3
Special Notes 7.7.2.3
Use 7.7.2.2
General Linearization PV Algorithm (GENLIN) 7.7.8
Changing Parameters through a Universal Station 7.7.8.3
Equation 7.7.8.4
Error Handling 7.7.8.3

APM Control Functions & Algorithms Index-6 12/03

 Index
Topic Section Heading

Example of Operation Figure 7-12

Extension of First and Last Segments 7.7.8.3
Function 7.7.8.1
Options and Special Features 7.7.8.3
Parameter — Value Restrictions 7.7.8.3
Restart or Point Activation 7.7.8.3
Use 7.7.8.2
Generic Modbus Interface to Array Point 10.3
GENLIN 7.7.8
Global Variables 9.1
Hardware Reference Addressing 3.5
High Selector, Low Selector, Average PV Algorithm
(HILOAVG) 7.7.4
Equations 7.7.4.4
Error Handling 7.7.4.3
Forced Selection 7.7.4.3
Function 7.7.4.1
Functional Diagram Figure 7-5
Options and Special Features 7.7.4.3
Restart or Point Activation 7.7.4.3
Use 7.7.4.2
HILOAVG 7.7.4
Idle-Run Transition 3.3.1
Inputs, Field
Analog
High Level 2.2
Low Level 2.2
Digital 2.5
Accumulation 2.5.3
Latched 2.5.2
Status 2.5.1
Smart Transmitter Interface 2.3
Incremental Summer (INCRSUM) Control Algorithm 8.14.9
Bad Control Handling 8.14.9.3.9
Changes to Output by User-Written Programs 8.14.9.3.4
Control Input Connections 8.14.9.3.1
Engineering Unit Ranges 8.14.9.3.3
Equations 8.14.9.4
Full Value, Floating PID Outputs, handling of 8.14.9.3.2
Function 8.14.9.1
Functional Diagram Figure 8-26
Initialization 8.14.9.5
Modes, Operating 8.14.9.3.6
Options and Special Features 8.14.9.3
Override Control Strategy 8.14.9.3.5
Remote Cascade Options 8.14.9.3.7
Restart or Point Activation 8.14.9.3.8
Use 8.14.9.2

APM Control Functions & Algorithms Index-7 12/03

 Index
Topic Section Heading

Interlocks 4.4
Overrides 4.4.2
Permissives 4.4.1
Types, 4.4
I/O Functions — see "Inputs, Field" or "Outputs, Field"
I/O Points — see "Inputs, Field"or "Outputs, Field"
LLMUX Data Point 2.2
Logic Point
Algorithms 5.3
AND Gate 5.3.2
Check for Bad 5.3.17
Compare Equal with Deadband 5.3.11
Compare Greater Than or Equal with Deadband 5.3.14
Compare Greater Than with Deadband 5.3.13
Compare Less Than or Equal with Deadband 5.3.16
Compare Less Than with Deadband 5.3.15
Compare Not Equal with Deadband 5.3.12
Delay 5.3.21
Fixed Size Pulse 5.3.18
Flipflop 5.3.25
NAND Gate 5.3.5
NOR Gate 5.3.6
NOT Gate 5.3.4
Null 5.3.1
Off Delay 5.3.23
On Delay 5.3.22
OR Gate 5.3.3
Pulse with Maximum Time Limit 5.3.19
Pulse with Minimum Time Limit 5.3.20
Qualified OR Gate with 2 Inputs On 5.3.8
Qualified OR Gate with 3 Inputs On 5.3.9
Switch 5.3.10
Watchdog Timer 5.3.24
XOR Gate 5.3.7
Configuring the Logic Point 5.2
Connections
Input 5.2.1
Communication and Configuration Errors 5.2.1.1
Output 5.2.5
Descriptors, Generic 5.2.6
Logic Mix 5.2
Flags 5.2.2
Numerics 5.2.3
Low-Level Multiplexer Data Point 2.2
Manual/Auto Station, SDI Interface 2.9.2
Memory Units (MU) 3.1.3
Message Text, see Status Messages
Middle of Three Selector PV Algorithm (MIDOF3) 7.7.3
Equations (forms of) 7.7.3.4
Error Handling 7.7.3.3
Function 7.7.3.1

APM Control Functions & Algorithms Index-8 12/03

 Index
Topic Section Heading

Functional Diagram Figure 7-4

Normal Operation with 3 Valid Inputs 7.7.3.3
Options and Special Features 7.7.3.3
Use 7.7.3.2
MIDOF3 7.7.3
Modbus Interface Through SI Array Point 10.3
Motor Control Point, see Device Control Point 10.3.4.2NIM
Maximum number of points 1.2.1
Numerics
Logic Point 5.2.3
APM Box 9.3
Process Module Data Point 6.1
Out of Service, Points 1.4
Output/Setpoint (SP/OP) Tolerance Check 8.8
Outputs, Analog
Calibration Compensation 2.4.3
Direct/Reverse 2.4.1
Output Characterization 2.4.2
Outputs, Digital
Pulse Width Modulated (PWM) 2.6.1
Status 2.6.2
Outputs, Digital Composite
Commanded State 4.6
Latched 4.6.1
Pulsed 4.6.2
Override Selector (ORSEL) Control Algorithm 8.14.11
Override and Bypass Options 8.14.11.3.2
Control Input Connections 8.14.11.3.1
Engineering Unit Ranges 8.14.11.3.3
Equations 8.14.11.4
Error Handling 8.14.11.3.7
Function 8.14.11.1
Functional Diagram Figure 8-30
Example of an Override Control Strategy Figure 8-31
Initialization 8.14.11.5
Modes, Operating 8.14.11.3.4
Options and Special Features 8.14.11.3
Override Control 8.13
Override-Feedback Initiation 8.14.11.6.1
Override Offset 8.14.11.3.2
Remote Cascade Options 8.14.11.3.5
Restart or Point Activation 8.14.11.3.6
Use 8.14.11.2
Peer-to-Peer Communications 3.4

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Topic Section Heading

PID Control Algorithm — see Proportional,

Integral, Derivative
PID with External Reset-Feedback (PIDERFB) Algorithm 8.14.3
Engineering Unit Ranges 8.14.3.3.3
Equations 8.14.3.4
Error Handling, RFB and TRFB Inputs 8.14.3.3.1
Function 8.14.3.1
Functional Diagram Figure 8-8
Hand Auto Stations
Configuration and Wiring Diagram Figure 8-10
Logic Point Configuration Figure 8-11
Requirements for Interface 8.14.3.2.2
Hand Auto Stations, use of 8.14.3.2.1
Initialization 8.14.3.5
Initialization and Windup Protection (Note) 8.14.3.3.2
Operating Modes 8.14.3.3.4
Output Connections 8.14.3.3.2
Override Feedback Processing 8.14.3.6
Remote Cascade Options 8.14.3.3.5
Uses 8.14.3.2
PID with Feedforward (PIDFF) Control Algorithm 8.14.2
Add or Multiply Action 8.14.2.3.1
Bypassing Feedforward Control Action 8.14.2.3.2
Equations 8.14.2.4
Example, in Feed Heater Control Figure 8-7
Feedforward Signal Value Status 8.14.2.3.3
Function 8.14.2.1
Functional Diagram Figure 8-6
Initialization 8.14.2.5
Modes, Operating 8.14.2.3.4
Override Feedback Processing 8.14.2.6
Options and Special Features 8.14.2.3
Remote Cascade Options 8.14.2.3.5
Use 8.14.2.2
PID Position Proportional Controller (PIDPOSPROP) Algorithm 8.14.5
Analog Output Related Parameters 8.14.5.5
Bad PV/Mode Shed 8.14.5.7
Equations 8.14.5.4
Functional Diagram Figure 8-14
Options and Special Features 8.14.5.3
Safety Shutdown 8.14.5.6
Use 8.14.5.2
Point Reservation 3.7
Point Types
Analog Input, High Level and Low Level 2.2
Analog Input, Smart Transmitter Interface 2.3
Array Points 10.1
Digital Input 2.5
Digital Inputs for Sequence Of Events 2.9
Digital Output 2.6
Digital Composite 4.1

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Topic Section Heading

Flag, Box 9.2

Full/Component Points 1.2.1
Logic Point 5.1
Numeric, Box 9.3
Primary Module (PRIMMOD) point 1.3.4
Process Module 6.1
Pulse Input 2.7
Regulatory Control 8.1
Regulatory PV 7.1
Sequence Of Events (see Digital Inputs)
Smart Transmitter Interface 2.3
Strings, Box 9.6
Timer, Box 9.4.4
Times, Box 9.5
Points, Maximum Number of 1.2.1
Position Proportional Controller (POSPROP) Algorithm 8.14.4
Analog Output Related Parameters 8.14.4.3.9
Engineering Unit Ranges 8.14.4.3.8
Equations 8.14.4.4
Example of in Step Valve Control Strategy Figure 8-13
Function 8.14.4.1
Initialization 8.14.4.5
Modes 8.14.4.3.1
One-Shot Control Initialization (Note) 8.14.4.5
Options and Special Features 8.14.4.3
Output Manipulation in Manual Mode 8.14.4.3.3
PV Source Selection 8.14.4.3.7
Raise/Lower Output Destinations 8.14.4.3.5
Remote Cascade Options 8.14.4.3.2
Setpoint Options 8.14.4.3.6
Use 8.14.4.2
Windup Feedback Limit Switches 8.14.4.3.4
Primary Module (PRIMMOD) Point 1.3.4
Processing Units (PUs) 3.1.3
Process Module Data Point 6.1
CL/APM Sequence Program 6.1.1
Local Flags, Numerics, Times, and Strings 6.1.1, 6.1.3.2
Process Module Operating State 6.1.6
Restart Option 6.1.12
Sequence Alarms 6.1.10
Sequence Execution 6.1.5
Sequence Execution Mode 6.1.7
Sequence Execution State 6.1.8
Sequence Library 6.1.3.1
Sequence Messages 6.1.11
Sequence Overrides 6.1.9
Sequence Program/Unit Partitioning 6.1.2
Sequence Program Structure 6.1.4
Writing the Sequence Programs 6.1.3

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Topic Section Heading

Proportional, Integral, Derivative (PID) Control Algorithm 8.14.1

Bias Options 8.14.1.3.12
Control by a Single Term 8.14.1.3.4
Control Output Connections 8.14.1.7
Direct and Reverse Control Action 8.14.1.3.5
Engineering Unit Ranges 8.14.1.3.2
Equations 8.14.1.4
Error Handling 8.14.1.3.16
Four Combinations of Control Terms 8.14.1.3.3
Function 8.14.1.1
Gain Options 8.14.1.3.7
Initialization 8.14.1.5
Initializing PID Output without Affecting Dynamics 8.14.1.3.10
Interactive and Noninteractive PID Forms 8.14.1.3.1
Operating Modes 8.14.1.3.13
Options and Special Features 8.14.1.3
Override Feedback Processing 8.14.1.6
Parameters 8.14.1.7
PV Tracking 8.14.1.3.6
Remote Cascade Options 8.14.1.3.14
Restart or Point Activation 8.14.1.3.15
Restrictions on Some Values 8.14.1.3.11
Suppression of Output "Kicks" When Switching to
CAS Mode 8.14.1.3.9
Use 8.14.1.2
Windup Handling 8.14.1.3.8
Pulse Input Point 2.7
PV Algorithms 7.7
Ramp and Soak (RAMPSOAK) Control Algorithm 8.14.7
Changing Remaining Soak Time and Current Segment 8.14.7.3.4
Control Input Connections 8.14.7.3.11
Engineering Unit Ranges 8.14.7.3.9
Equations 8.14.7.4
Function 8.14.7.1
Functional Diagram Figure 8-18
Guaranteed Ramp Rate 8.14.7.3.6
Guaranteed Soak Time 8.14.7.3.5
Limits of Deviation, Output and Setpoint 8.14.7.3.9
Longer Sequences, Achieving by Interconnecting 8.14.7.3.8
Use of Logic Point in Longer Sequence Figure 8-22
Mark Timer Functions 8.14.7.3.7
Pictured Figure 8-21
Operational Modes 8.14.7.3.2
Options and Special Features 8.14.7.3
Override Feedback Processing 8.14.7.5
Parameters (for RAMPSOAK0) 8.14.7.6
Ramping Waits for Process Figure 8-20
Remote Cascade Options 8.14.7.3.3

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Restart or Point Activation 8.14.7.3.10

Single or Cyclic Sequencing 8.14.7.3.1
Use 8.14.7.2
Wait Time between Phases Figure 8-19
Ratio Control (RATIOCTL) Control Algorithm 8.14.6
Calculator PV Algorithm, Role of 8.14.6.3.3
Control Input Connections 8.14.6.3.1
Engineering Unit Ranges 8.14.6.3.2
Equations 8.14.6.4
Error Handling 8.14.6.3.7
Example of Figure 8-17
Function 8.14.6.1
Functional Diagram Figure 8-15
Initialization 8.14.6.5
Modes, Operating 8.14.6.3.4
Options and Special Features 8.14.6.3
Override Feedback Processing 8.14.6.6
Functional Diagram of Figure 8-17
Remote Cascade Options 8.14.6.3.5
Restart or Point Activation 8.14.6.3.6
Use 8.14.6.2
Read-Back Check, DevCtl or DigCmp points 4.8, 10.3.4
Red Tagging 1.4
Redundancy 3.6
Regulatory Control Data Point
Alarming
Advisory Deviation Alarming 8.7.4
Bad Output Alarm 8.7.5
Detection 8.9
Deviation Alarming 8.7.4
Output High/Low Alarms 8.10.7
Bias Option 8.7.6
Connections
Input 8.2
Output 8.10.6
Control Output Processing 8.10
Initialization 8.10
PV 8.11.1
Control 8.11.2
Limits
Bias Limits 8.7.6.1
Output High and Low 8.10.2
Output Rate-of-Change 8.10.3
Output Minimum Change 8.10.4
Output Limiting in Manual Mode 8.10.5
Ratio Limits 8.7.6.2
Setpoint 8.7.1
Modes 8.4
External Mode Switching 8.6
Mode Attribute 8.4.1
Normal Mode Attribute 8.4.3

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Normal Mode 8.4.2

Remote Cascade Handling 8.4.4
Remote Cascade Options 8.4.4.1
Remote Cascade Shed 8.4.4.3
Remote Cascade Request 8.4.4.2
Override Control 8.13
Guideline for use of 8.13.3
Processing 8.13.2
Status and Feedback 8.13.1
PV
Source Selection 8.3
Tracking 8.7.3
Ratio Option 8.7.6
Setpoint
Access Restrictions 8.7.7
Handling 8.7
Limits 8.7.1
Target Value Processing 8.7.2
Shutdown, Safety 8.5
Windup
Protection 8.12
Status 8.12.1
Status Propagation 8.12.2
Regulatory PV Data Point
Input Connections 7.2
PV
Alarm Detection 7.6
Range Check and Filtering 7.4
Source Selection 7.5
Value Status 7.4.1
Restart, Warm Cold 3.9
Restrictions on Delay Time (see also Variable Dead Time
with Lead Lag) 7.7.6.3
Reservation, Point 3.7
RHMuX Data Point 2.2
SDI see Serial Device Interface
Sensor Types, Field Table 2-1
Sequence Of Events Digital Input Point 2.5.4
Sequence Program, CL/APM 6.1.1
Alarms 6.1.10
Execution 6.1.5
Execution Mode 6.1.7
Execution State 6.1.8
Library 6.1.3.1
Messages 6.1.11
Overrides 6.1.9
Process Module Data Point 6.1
Program Structure 6.1.4
Restart Option 6.1.12
Unit Partitioning 6.1.2
Writing the 6.1.3

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 Index
Topic Section Heading

Serial Device Interface 2.9

Description 2.9.1
Manual/Auto Station Interface 2.9.2
Toledo Weigh Scale Interface 2.9.3
Serial Interface 2.8
Operation 2.8.1
Configuration 2.8.2
Checkpointing and Startup 2.8.3
Serial Interface to Array Points 10.3
Configuration 10.3
Generic Modbus Interface 10.3.2.2
Allen-Bradley PLC Interface 10.3.2.2
SI Array Point 10.3
Setpoint/Output (SP/OP) Tolerance Check 8.8
Smart Transmitter Interface Point 2.3
Alarming 2.3.2.7
Commands 2.3.6
Communication Modes 2.3.3
Component Point Usage Example Figure 1-2
Database
Considerations 2.3.4
Mismatches 2.3.4
Detail Display Figure 2-2
Functions 2.3.2
Linear Conversion 2.3.2.2
Number of Points per STI Card 1.1.1
Point States 2.3.5
PV Characterization 2.3.2.1
PV Characterization Options Table 2-3
PV Range Checking and Filtering 2.3.2.5
PV Source Selection 2.3.2.6
Smart Field Communicator 2.3, 2.3.4
Square Root Conversion 2.3.2.3
Status
STI 2.3.5
Transmitter 2.3.4
Thermal Conversion 2.3.2.4
Transmitter/STI IOP Parameter Comparisons 2.3.1
Transmitter Types Supported 2.3
Use of Damping vs. TF 2.3.2.5
Valid Damping Values 2.3.2.5
States, Digital
Current Input (PV) 4.12
Normal 4.2.1
Momentary 4.2.2
Moving/Bad 4.2.3
Status Messages 3.8
Strings, Box 9.6

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SUMMER 7.7.5
Summer Algorithm (SUMMER) PV Algorithm 7.7.5
Ensuring Adequate PV Range 7.7.5.3
Equations 7.7.5.4
Error Handling 7.7.5.3
Function 7.7.5.1
Functional Diagram Figure 7-6
Options and Special Features 7.7.5.3
Restart or Point Activation 7.7.5.3
Use7.7.5.2
Switch (SWITCH) Control Algorithm 8.14.10
Control Input Connections 8.14.10.3.1
Engineering Unit Ranges 8.14.10.3.2
Equations 8.14.10.4
Error Handling 8.14.10.3.9
Examples Figure 8-29
Function 8.14.10.1
Functional Diagram Figure 8-28
Initialization 8.14.10.5
Modes, Operational 8.14.10.3.6
Options and Special Features 8.14.10.3
Override Feedback Processing 8.14.10.6
Parameters 8.14.10.7
Positions of Switch
Control of by Operator (Equation A) 8.14.10.3.3
Control of with Equation B 8.14.10.3.4
Remote Cascade Options 8.14.10.3.7
Restart or Point Activation 8.14.10.3.8
Tracking Option 8.14.10.3.5
Use 8.14.10.2
Time-Constant Recommendations (see also
Variable Dead Time with Lead Lag) 7.7.6.3
Timer, Box 9.4
Times, Box 9.5
Toledo Weigh Scale Interface 2.9.3
Totalizer Algorithm (TOTALIZR) 7.7.7
Accumulated Value before Reset 7.7.7.3
Bad-Input and Warm-Restart Options 7.7.7.3
Command Flags 7.7.7.3
Commands, States and Command Flags 7.7.7.3
Diagram of Use Figure 7-9
Equations 7.7.7.4
Error Handling 7.7.7.3
Function 7.7.7.1
Near-Zero Cutoff 7.7.7.3
Restart or Point Activation 7.7.7.3
Special Features 7.7.7.3
Target-Value Flags 7.7.7.3
Time Base and Engineering Units Scaling 7.7.7.3
Typical Operation 7.7.7.3
Use 7.7.7.2

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Topic Section Heading

TOTALIZR 7.7.7
USERID 3.7
Variable Dead Time with Lead-Lag Compensation Algorithm
(VDTLDLG) 7.7.6
Changing Dead-Time (Delay-Time) Parameters 7.7.6.3
Dead Time (Delay-Time) Calculation 7.7.6.3
Equations (forms of) 7.7.6.4
Error Handling 7.7.6.3
Four Combinations of Delay and Lead-Lag
Compensation 7.7.6.3
Function 7.7.6.1
Functional Diagram Figure 7-7
Options and Special Features 7.7.6.3
Restrictions on Delay Time 7.7.6.3
Time Constant Recommendations 7.7.6.3
Use 7.7.6.2
Variable-Delay Time Example 7.7.6.3
VDTLDLG 7.7.6
Warm Cold Restart 3.3.2
Windup 8.14.1.3.8

APM Control Functions & Algorithms Index-17 12/03

APM Control Functions & Algorithms 12/03
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