USER’S MANUAL

FX2N-2LC Temperature Control Block

FX2N-2LC Temperature Control Block

Foreword

• This manual contains text, diagrams and explanations which will guide the reader in the cor-
rect installation and operation of the communication facilities of FX series.

• Before attempting to install or use the communication facilities of FX series this manual
should be read and understood.

• If in doubt at any stage of the installation of the communication facilities of FX series always
consult a professional electrical engineer who is qualified and trained to the local and
national standards which apply to the installation site.

• If in doubt about the operation or use of the communication facilities of FX series please
consult the nearest Mitsubishi Electric distributor.

• This manual is subject to change without notice.

FX2N-2LC Tempereture Control Block

FX2N-2LC
Temperature Control Block

USER’S MANUAL

Manual number : JY992D85801

Manual revision : F
Date : 4/2015

i
FX2N-2LC Tempereture Control Block

ii
FX2N-2LC Tempereture Control Block

Guidelines for the Safety of the User and Protection of the Temperature control
block FX2N-2LC.
This manual provides information for the use of the Temperature control block FX2N-2LC. The
manual has been written to be used by trained and competent personnel. The definition of
such a person or persons is as follows;
a) Any engineer who is responsible for the planning, design and construction of automatic
equipment using the product associated with this manual should be of a competent
nature, trained and qualified to the local and national standards required to fulfill that
role. These engineers should be fully aware of all aspects of safety with regards to
automated equipment.
b) Any commissioning or service engineer must be of a competent nature, trained and
qualified to the local and national standards required to fulfill that job. These engineers
should also be trained in the use and maintenance of the completed product. This
includes being completely familiar with all associated documentation for the said product.
All maintenance should be carried out in accordance with established safety practices.
c) All operators of the completed equipment (see Note) should be trained to use this
product in a safe manner in compliance to established safety practices. The operators
should also be familiar with documentation which is associated with the operation of the
completed equipment.
Note : Note: the term ‘completed equipment’ refers to a third party constructed device which
contains or uses the product associated with this manual.
Notes on the Symbols Used in this Manual
At various times throughout this manual certain symbols will be used to highlight points of
information which are intended to ensure the users personal safety and protect the integrity of
equipment. Whenever any of the following symbols are encountered its associated note must
be read and understood. Each of the symbols used will now be listed with a brief description of
its meaning.
Hardware Warnings

1) Indicates that the identified danger WILL cause physical and property damage.

2) Indicates that the identified danger could POSSIBLY cause physical and property
damage.

3) Indicates a point of further interest or further explanation.

Software Warnings

4) Indicates special care must be taken when using this element of software.

5) Indicates a special point which the user of the associate software element should
be aware of.

6) Indicates a point of interest or further explanation.

iii
FX2N-2LC Tempereture Control Block

• Under no circumstances will Mitsubishi Electric be liable responsible for any consequential
damage that may arise as a result of the installation or use of this equipment.

• All examples and diagrams shown in this manual are intended only as an aid to
understanding the text, not to guarantee operation. Mitsubishi Electric will accept no
responsibility for actual use of the product based on these illustrative examples.

• Please contact a Mitsubishi Electric distributor for more information concerning applications
in life critical situations or high reliability.

iv
FX2N-2LC Temperature Control Block Contents

Guidelines ....................................................................................................iii

1. Introduction ........................................................................................... 1-1

1.1 Outline of product ................................................................................................ 1-2

2. Product Configuration ........................................................................... 2-1

2.1 Outside dimension............................................................................................... 2-1
2.2 Name of each part ............................................................................................... 2-1
2.3 Status indication .................................................................................................. 2-2
2.4 Installation method .............................................................................................. 2-3
2.5 Connection to PLC Main Unit .............................................................................. 2-4

3. Specifications ........................................................................................ 3-1

3.1 General specifications ......................................................................................... 3-1
3.2 Power supply specifications ................................................................................ 3-1
3.3 Performance specifications ................................................................................. 3-2
3.4 Input specifications .............................................................................................. 3-3
3.5 Input range .......................................................................................................... 3-4
3.6 Output specifications ........................................................................................... 3-5

4. Wiring .................................................................................................... 4-1

4.1 Wiring .................................................................................................................. 4-2
4.2 Crimp terminal ..................................................................................................... 4-3

5. Introduction of Functions....................................................................... 5-1

5.1 PID control........................................................................................................... 5-1
5.1.1 Easy PID control with two degrees of freedom.......................................................... 5-1
5.1.2 Overshoot prevention function................................................................................... 5-2
5.2 Two-position control ............................................................................................ 5-3
5.3 Auto tuning function............................................................................................. 5-4
5.3.1 AT (auto tuning)......................................................................................................... 5-4
5.3.2 Conditions for performing and aborting AT................................................................ 5-5
5.3.3 AT bias ...................................................................................................................... 5-6
5.4 Auto / manual ...................................................................................................... 5-7
5.4.1 Auto mode and manual mode ................................................................................... 5-7
5.4.2 Balance-less, bump-less function.............................................................................. 5-7
5.5 Heater disconnection alarm function ................................................................... 5-8
5.6 Loop breaking alarm function (LBA) .................................................................... 5-9

6. Alarm..................................................................................................... 6-1

v
FX2N-2LC Temperature Control Block Contents

7. Buffer Memory (BFM) ........................................................................... 7-1

7.1 Buffer memory list................................................................................................ 7-1
7.2 Details of buffer memories................................................................................... 7-4
7.2.1 BFM #0: Flag ............................................................................................................. 7-4
7.2.2 BFM #1 (CH1) and BFM #2 (CH2): Event ................................................................. 7-5
7.2.3 BFM #3 (CH1) and BFM #4 (CH2): Measured value (PV) ........................................ 7-7
7.2.4 BFM #5 (CH1) and BFM #6 (CH2): Control output value (MV) ................................. 7-7
7.2.5 BFM #7 (CH1) and BFM #8 (CH2): Heater current measured value......................... 7-7
7.2.6 BFM #9: Initialization command ................................................................................ 7-7
7.2.7 BFM #10: Error reset command ................................................................................ 7-7
7.2.8 BFM #11: Control start/stop changeover................................................................... 7-7
7.2.9 BFM #12 (CH1) and BFM #21 (CH2) : Set value (SV) .............................................. 7-8
7.2.10 BFM #13 to BFM #16 (CH1) and BFM #22 to BFM #25 (CH2): Alarm 1/2/3/4
set value .................................................................................................................... 7-8
7.2.11 BFM #17 (CH1) and BFM #26 (CH2): Heater disconnection alarm set value ........... 7-8
7.2.12 BFM #18 (CH1) and BFM #27 (CH2) : Auto/manual mode changeover ................... 7-8
7.2.13 BFM #19 (CH1) and BFM #28 (CH2): Manual output set value ................................ 7-9
7.2.14 BFM #20 (CH1) and BFM #29 (CH2): Auto tuning execution command................... 7-9
7.2.15 BCM#30: Unit type code............................................................................................ 7-9
7.2.16 BFM #32 (CH1) and BFM #51 (CH2): Operation mode ............................................ 7-9
7.2.17 BFM #33 (CH1) and BFM #52 (CH2): Proportional band (P) .................................... 7-9
7.2.18 BFM #34 (CH1) and BFM #53 (CH2): Integral time (I) ............................................ 7-10
7.2.19 BFM #35 (CH1) and BFM #54 (CH2): Derivative time (D) ...................................... 7-10
7.2.20 BFM #36 (CH1) and BFM #55 (CH2): Control response parameter ....................... 7-11
7.2.21 BFM #37 (CH1) and BFM #56 (CH2): Output limiter upper limit
BFM #38 (CH1) and BFM #57 (CH2): Output limiter lower limit.............................. 7-12
7.2.22 BFM #39 (CH1) and BFM #58 (CH2): Output change ratio limiter .......................... 7-13
7.2.23 BFM #40 (CH1) and BFM #59 (CH2): Sensor correction value setting (PV bias) ... 7-14
7.2.24 BFM #41 (CH1) and BFM #60 (CH2): Adjustment sensitivity (dead zone) setting.. 7-15
7.2.25 BFM #42 (CH1) and BFM #61 (CH2): Control output cycle setting......................... 7-15
7.2.26 BFM #43 (CH1) and BFM #62 (CH2): Primary delay digital filter setting ................ 7-16
7.2.27 BFM #44 (CH1) and BFM #63 (CH2): Setting change ratio limiter.......................... 7-17
7.2.28 BFM #45 (CH1) and BFM #64 (CH2): AT (auto tuning) bias................................... 7-18
7.2.29 BFM #46 (CH1) and BFM #65 (CH2): Normal/reverse operation selection ............ 7-18
7.2.30 BFM #47 (CH1) and BFM #66 (CH2): Setting the upper limit
BFM #48 (CH1) and BFM #67 (CH2): Setting the lower limit .................................. 7-19
7.2.31 BFM #49 (CH1) and BFM #68 (CH2): Loop breaking alarm judgement time.......... 7-20
7.2.32 In BFM #50, set the loop breaking alarm dead zone of CH1.
In BFM #69, set the loop breaking alarm dead zone of CH2................................... 7-21
7.2.33 BFM #70 (CH1) and BFM #71 (CH2): Input type selection ..................................... 7-22
7.2.34 BFM #72 to BFM #75: Alarm mode setting ............................................................. 7-23
7.2.35 BFM #76: Alarm 1/2/3/4 dead zone setting ............................................................. 7-25
7.2.36 BFM #77: Number of times of alarm 1/2/3/4 delay .................................................. 7-26
7.2.37 BFM #78: Number of times of heater disconnection alarm delay............................ 7-26
7.2.38 BFM #79: Temperature rise completion range setting ............................................ 7-26
7.2.39 BFM #80: Temperature rise completion soak time.................................................. 7-27
7.2.40 BFM #81: CT monitor method changeover ............................................................. 7-27
7.2.41 BFM #82: Set value range error address ................................................................ 7-27
7.2.42 BFM #83: Set value backup command.................................................................... 7-28

8. Program Example ................................................................................. 8-1

8.1 Program example ................................................................................................ 8-2

9. Diagnostic ............................................................................................. 9-1

vi
FX2N-2LC Temperature Control Block Introduction 1

1 Introduction 1

2 Product Configuration

3 Specifications

4 Wiring

5 Introduction of Functions

6 Alarm

7 Buffer Memory (BFM)

8 Program Example

9 Diagnostic
FX2N-2LC Temperature Control Block Introduction 1
FX2N-2LC Temperature Control Block Introduction 1

1. Introduction
1
Cautions on design
• Install a safety circuit outside the PLC or the temperature control block FX2N-2LC so that
the entire system conservatively operates even if an abnormality occurs in the external
power supply or a failure occurs in the PLC or the FX2N-2LC.
If a safety circuit is installed inside the PLC, malfunction and erroneous output may
cause accidents.
1) Make sure to construct an emergency stop circuit, protection circuit or interlock circuit to
prevent damages of a machine, etc. outside the PLC or the FX2N-2LC.
2) If the PLC or the FX2N-2LC detects an abnormality such as a watch dog timer error or
input value error by the self-diagnosis function or when an abnormality occurs in the I/O
control area, etc. which cannot be detected by the CPU in the PLC, output control may
be disabled.
Design external circuits and structure so that the entire system conservatively operates
in such cases.
3) If a failure occurs in a relay, transistor, TRIAC, etc. in an output unit of the FX2N-2LC or
the PLC, outputs may keep ON or OFF.
For output signals which may lead to severe accidents, design external circuits and
structure so that the entire system conservatively operates.

Cautions on installation
• Use the unit in the environment for the general specifications described in the manual.
Never use the unit in a place with dusts, soot, conductive dusts, corrosive gas or
flammable gas, place exposed to high temperature, dew condensation or rain and wind
or place exposed to vibration or impact.
If the unit is used in such a place, electrical shock, fire, malfunction, damages in the unit
or deterioration of the unit may be caused.
• Never drop cutting chips or electric wire chips into the ventilation window of the FX2N-
2LC while drilling screw holes or wiring cables.
Such chips may cause fire, failure or malfunction.
• After finishing installation, remove a dust preventing sheet adhered on the ventilation
window of the PLC and the FX2N-2LC.
If the sheet remains attached, fire, failure or malfunction may be caused.
• Securely connect cables such as extension cables and memory cassettes to specified
connectors.
Imperfect contact may cause malfunction.

Caution on disposal
• When disposing of the unit, treat it as industrial waste.

1-1
 FX2N-2LC Temperature Control Block Introduction 1

1.1 Outline of product

The temperature control block FX2N-2LC (hereafter referred to as "temperature control block"
or "FX2N-2LC") equipped with two temperature input points and two transistor (open collector)
output points is a special block to read temperature signals from thermocouples and platinum
resistance thermometer bulbs, and perform PID output control.
Connect the FX2N-2LC to the FX1N/FX2N/FX2NC/FX3U/FX3UC Series PLC.
1) As input sensors, two thermocouples, two platinum resistance thermometer bulbs or one
thermocouple and one platinum resistance thermometer bulb are available.
2) Data can be written and read using FROM/TO instructions when the FX2N-2LC is connected
to the FX1N/FX2N/FX2NC/FX3U/FX3UC Series PLC.
(The FX2N-2LC performs arithmetic operation for PID control and output control. You do not
have to create sequence programs for PID operation.)
3) Disconnection of heaters can be detected by current detection (CT).
4) The proportional band, the integral time and the derivative time can be easily set by auto
tuning.
5) Channels are isolated against each other.

1-2
FX2N-2LC Temperature Control Block Product Configuration 2

1 Introduction

2 Product Configuration 2

3 Specifications

4 Wiring

5 Introduction of Functions

6 Alarm

7 Buffer Memory (BFM)

8 Program Example

9 Diagnostic
FX2N-2LC Temperature Control Block Product Configuration 2
 FX2N-2LC Temperature Control Block Product Configuration 2

2. Product Configuration

2.1 Outside dimension

Unit: mm (inches)
Mass: 0.3kg (0.66lbs)
Outer color: Munsell 0.08GY / 7.64 / 0.81

2.2 Name of each part

Terminal block
24+
24- OUT1OUT2
CT COM
CT
CH1
PTA

FG PTB
PTB
TC+
TC-
CT PTA PTB

① :PLC connection cable

CT FG PTB
CH2

② :Screw mounting hole

③ :24V DC/Input/Output terminal (M3 terminal screws)
TC+

④
TC-

:Status indicator LED

⑤ :DIN rail mounting groove (DIN rail width: 35mm(1.38"))
⑥ :DIN rail mounting hook
⑦ :Connector for next step extension cable

2-1
 FX2N-2LC Temperature Control Block Product Configuration 2

2.3 Status indication

Table 2.1:
LED name Indication Description
Lit (green) 5 V power is supplied from PLC main unit.
POWER
Extinguished 5 V power is not supplied from PLC main unit.
Lit (red) 24 V power is supplied from outside.
24V
Extinguished 24 V power is not supplied from outside.
Lit (red) OUT1 output is ON.
OUT1
Extinguished OUT1 output is OFF.
Lit (red) OUT2 output is ON.
OUT2
Extinguished OUT2 output is OFF.

2-2
 FX2N-2LC Temperature Control Block Product Configuration 2

2.4 Installation method

The FX2N-2LC can be installed on the right side of an FX1N/FX2N/FX2NC/FX3U/FX3UC Series
PLC main unit, FX2N/FX2NC/FX3U/FX3UC Series extension unit or another extension block.
The FX2N-2LC can be attached with a DIN rail DIN46277 (width: 35 mm) or directly attached to
a panel surface with screws (M4).
2
• Installation on DIN rail
Align the upper side of the DIN rail mounting groove of the FX 2N -2LC with a DIN rail
DIN46277 (width: 35 mm) (①), and push the FX2N-2LC on the DIN rail (②).
When removing the FX2N-2LC, pull out downward the DIN rail mounting hook (③), then
remove the FX2N-2LC (④).

When attaching to DIN rail When removing from DIN rail

➁ ➂

• Direct installation on panel surface

Screw-tighten the FX2N-2LC with M4 screws to a panel surface using two (upper and lower)
mounting holes provided on the left side of the FX2N-2LC.
Assure the interval of 1 to 2 mm between a unit or block installed on the left side of the
FX2N-2LC.

Cautions on installation
• Use the unit in the environment for the general specifications described in the manual.
Never use the unit in a place with dusts, soot, conductive dusts, corrosive gas or
flammable gas, place exposed to high temperature, dew condensation or rain and wind
or place exposed to vibration or impact.
If the unit is used in such a place, electrical shock, fire, malfunction, damages in the unit
or deterioration of the unit may be caused.
• Never drop cutting chips or electric wire chips into the ventilation window of the FX2N-
2LC while drilling screw holes or wiring cables.
Such chips may cause fire, failure or malfunction.
• After finishing installation, remove a dust preventing sheet adhered on the ventilation
window of the PLC and the FX2N-2LC.
If the sheet remains attached, fire, failure or malfunction may be caused.
• Securely connect cables such as extension cables and memory cassettes to specified
connectors.
Imperfect contact may cause malfunction.

2-3
 FX2N-2LC Temperature Control Block Product Configuration 2

2.5 Connection to PLC Main Unit

Connect the FX2N-2LC to the PLC main unit with an extension cable.
FX2N-2LC units are treated as special blocks of the PLC, and the special block No. 0 to 7 is
automatically assigned to each FX2N-2LC unit from the one nearest to the PLC main unit.
(These unit Nos. are used in FROM/TO instructions.)
One FX2N-2LC unit occupies eight I/O points in the PLC main unit.
For the details of I/O assignment in the PLC, refer to the respective FX1N/FX2N/FX2NC/FX3U/
FX3UC Series PLC manual.

• Up to eight FX2N-2LC units can be connected to the FX1N/FX2N/FX3U/FX3UC*1 Series PLC.

Up to four FX2N-2LC units can be connected to the FX2NC Series PLC.

• When connecting the FX2N-2LC unit to the FX2NC Series PLC, the interface FX2NC-CNV-IF
is required.

• For extension, an extension cable FX0N-65EC (650 mm) and the FX2N-CNV-BC sold
separately are required.
Only one FX0N-65EC can be used per system.
*1 Up to seven FX2N-2LC units can be connected to the FX3UC-32MT-LT PLC. Unit numbers
assigned to special function units/blocks begins with No.1.

2-4
FX2N-2LC Temperature Control Block Specifications 3

1 Introduction

2 Product Configuration

3 Specifications 3

4 Wiring

5 Introduction of Functions

6 Alarm

7 Buffer Memory (BFM)

8 Program Example

9 Diagnostic
FX2N-2LC Temperature Control Block Specifications 3
 FX2N-2LC Temperature Control Block Specifications 3

3. Specifications

3.1 General specifications

Table 3.1:
Item Specifications
500 VAC for 1 minute (between analog input terminal and grounding
Withstand voltage
terminal)

Other general specifications are equivalent to those for the PLC main unit. (Refer to the man- 3
ual of the PLC main unit.)

3.2 Power supply specifications

Table 3.2:
Item Specifications
Driving power supply 24 VDC (-15% to +10%), input from driving power supply terminal
Power supply for
5 VDC (supplied from inside of PLC main unit)
communication
Current consumption 24 VDC, 55 mA and 5 VDC, 70 mA
Analog input area and PLC are insulated by photocoupler.
Insulation method Power supply and analog input are insulated by DC/DC converter.
(Channels are insulated each other.)
Number of occupied I/O
8 points in total (including input points and output points)
points

3-1
 FX2N-2LC Temperature Control Block Specifications 3

3.3 Performance specifications

Table 3.3:
Item Description
Two-position control, PID control (with auto tuning function), PI
Control method
control
Control operation period 500 ms
Set temperature range Equivalent to input range (Refer to 7.2.33)
Alarm is detected in accordance with setting of buffer memory.
Heater disconnection detection
(Variable within range from 0.0 to 100.0 A.).
0: Measured value monitor
1: Measured value monitor + Temperature alarm
Operation mode
2: Measured value monitor + Temperature alarm + Control
(Selected by buffer memory)
Adjustment data and input value are checked by watch dog timer.
Self-diagnosis function
When abnormality is detected, transistor output turns OFF.
Memory Built-in EEPROM (Number of times of overwrite: 100,000 times)
Lit (green) 5 V power is supplied from PLC main unit.
POWER
Extinguished 5 V power is not supplied from PLC main unit.
Lit (red) 24 V power is supplied from outside.
24V
Status Extinguished 24 V power is not supplied from outside.
indication Lit (red) OUT1 output is ON.
OUT1
Extinguished OUT1 output is OFF.
Lit (red) OUT2 output is ON.
OUT2
Extinguished OUT2 output is OFF.

3-2
 FX2N-2LC Temperature Control Block Specifications 3

3.4 Input specifications

Table 3.4:
Item Description
Number of input points 2 points
K, J, R, S, E, T, B, N, PLII, WRe5=26, U, L
Thermocouple
JIS C 1602-1995
Input type Resistance
3-wire Pt100 JIS C 1604-1997,
thermometer
JPt100 JIS C 1604-1981
bulb
3
± 0.7 % of range span ± 1 digit
(± 0.3 % of range span ± 1 digit when ambient temperature
is 23 °C ± 5 °C)
Measurement precision
However, 0 to 399 °C (0 to 799 °F) in B inputs as well as 0
to 32 °F in PLII and WRe5-26 inputs are outside precision
guarantee range.
Within ± 1.0 °C
Cold contact temperature
However, within ± 2.0 °C while input value is -150 to -100
Temperature compensation error °C within ± 3.0 °C while input value is -200 to -150 °C
input
0.1 °C (0.1 °F) or 1 °C (1 °F)
Resolution
(Varies depending on input range of used sensors.)
Sampling period 500 mS
Effect of external
Approx. 0.35 µV/Ω
resistance
Input impedance 1 Μ Ω or more
Sensor current Approx. 0.3 mA
Allowable input lead wire
10 Ω or less
resistance
Operation when input is
Upscale
disconnected
Operation when input is
Downscale
short-circuited
Number of input points 2 points
CTL-12-S36-8 or CTL-6-P-H
Current detector
(manufactured by U.R.D. Co., Ltd.)
Heater When CTL-12
0.0 to 100.0 A
current is used
CT input
measured When CTL-6 is
value 0.0 to 30.0 A
used
Larger one between ± 5 % of input value and 2 A
Measurement precision
(excluding precision of current detector)
Sampling period 1 second

3-3
 FX2N-2LC Temperature Control Block Specifications 3

3.5 Input range

Table 3.5:
Sensor type K J R S
-200.0 to 200.0 °C
-200.0 to 200.0 °C
-100.0 to 400.0 °C
-100.0 to 400.0 °C
-100.0 to 800.0 °C 0 to 1700 °C 0 to 1700 °C
Input range -100 to 1300 °C
-100 to 1200 °C 0 to 3200 °F 0 to 3200 °F
-100 to 800 °F
-100 to 1600 °F
-100 to 2400 °F
-100 to 2100 °F

Sensor type E T B N
-200.0 to 200.0 °C
-200.0 to 400.0 °C
-200.0 to 200.0 °C
0.0 to 400.0 °C 0 to 1800 °C 0 to 1300 °C
Input range 0 to 1000 °C
-300.0 to 400.0 °F 0 to 3000 °F 0 to 2300 °F
0 to 1800 °F
-300.0 to 700.0 °F
0.0 to 700.0 °F

Sensor type PL II WRe5-26 U L

0 to 1200 °C 0 to 2300 °C -200.0 to 600.0 °C 0.0 to 900.0 °C
Input range
0 to 2300 °F 0 to 3000 °F -300.0 to 700.0 °F 0 to 1600 °F

Sensor type JPt100 Pt100

-50.0 to 150.0 °C -50.0 to 150.0 °C
-200.0 to 500.0 °C -200.0 to 600.0 °C
Input range
-300.0 to 300.0°F -300.0 to 300.0°F
-300 to 900 °F -300 to 1100 °F

• When B is used, 0 to 399 °C (0 to 799 °F) is outside the precision compensation range.

• When PLII is used, 0 to 32 °F is outside the precision compensation range.

• When WRe5-26 is used, 0 to 32 °F is outside the precision compensation range.

3-4
 FX2N-2LC Temperature Control Block Specifications 3

3.6 Output specifications

Table 3.6:
Item Description
Number of output points 2 points
Output method NPN open collector transistor output
Rated load voltage 5 to 24 VDC
Maximum load voltage 30 VDC or less
Maximum load current 100 mA
Leak current in OFF status 0.1 mA or less
3
Maximum voltage drop in ON status 2.5 V (maximum) or 1.0 V (typical) at 100 mA
Control output cycle 30 seconds (Variable within range from 1 to 100 seconds)

3-5
FX2N-2LC Temperature Control Block Specifications 3

MEMO

3-6
FX2N-2LC Temperature Control Block Wiring 4

1 Introduction

2 Product Configuration

3 Specifications

4 Wiring 4

5 Introduction of Functions

6 Alarm

7 Buffer Memory (BFM)

8 Program Example

9 Diagnostic
FX2N-2LC Temperature Control Block Wiring 4
FX2N-2LC Temperature Control Block Wiring 4

4. Wiring

Cautions on Wiring
• Make sure to shut down the power supplies of all phases on the outside before starting
installation or wiring.
If the power supplies are not shut down, you may get electrical shock or the unit may be
damaged.
• As to loads which are dangerous when turning ON at the same time, make sure to
interlock them outside the PLC and the FX2N-2LC in addition to interlocking of them in a
program in the PLC.

4
• Connect the power cable of the FX2N-2LC temperature control block and the PLC as
explained in the contents of this manual.
The product maybe seriously damaged if an AC power supply is connected to the DC
I/O terminal or DC power terminal.

• Never perform external wiring to unused terminals in the FX2N-2LC and the PLC.
Such wiring may damage the units.

• Perform Class 3 grounding with an electric wire of 2 mm2 or more to the grounding
terminal in the FX2N-2LC and the PLC.
However, never perform common grounding with a strong power system.

4-1
 FX2N-2LC Temperature Control Block Wiring 4

4.1 Wiring
When a temperature sensor is a thermocouple (TC)

AC power supply

DC24V
- +
FX2N-2LC

24+
24-
*1
SSR
OUT1
COM
SSR
OUT2
CT
CT
CT

PTA / •
FG Shielded cable
Heater
PTB / TC+
Thermocouple
PTB / TC-
CT
CT
CT

PTA / •
FG Shielded cable
Heater
PTB / TC+
Thermocouple
PTB / TC-

When a temperature sensor is a resistance thermometer bulb (RTD)

Resistance
FX2N-2LC thermometer
Shielded cable bulb
PTA / •
FG
PTB / TC+
PTB / TC-

*2 Connect the terminal in the FX2N-2LC to the terminal in the PLC to which Class
3 grounding is performed.

• When using a thermocouple, use specified compensating lead wires.

• When using a resistance thermometer bulb, use the three-wire type, and perform wiring
with lead wires having small resistance and no difference in the resistance among the three
wires.

• Terminal tightening torque: 0.5 to 0.8 N·m

4-2
 FX2N-2LC Temperature Control Block Wiring 4

4.2 Crimp terminal

When connecting one wire to a terminal screw, use a crimp terminal of the following
dimension and crimp it as shown in the diagram.
6.2mm(0.24") 6.2mm(0.24")
φ3.2(0.13")
or less Terminal screw Crimp terminal

Terminal
φ3.2(0.13")
or less

When connecting two wires to a terminal screw, use crimp terminals of the following
dimension and crimp them as shown in the diagram.
6.2mm(0.24") 6.2mm(0.24")

φ3.2(0.13")
or less

Terminal screw Crimp terminal

6.3mm(0.25") or more

φ3.2(0.13")
or less

Terminal

6.3mm(0.25") or more

4-3
FX2N-2LC Temperature Control Block Wiring 4

MEMO

4-4
FX2N-2LC Temperature Control Block Introduction of Functions 5

1 Introduction

2 Product Configuration

3 Specifications

4 Wiring

5 Introduction of Functions 5

6 Alarm

7 Buffer Memory (BFM)

8 Program Example

9 Diagnostic
FX2N-2LC Temperature Control Block Introduction of Functions 5
 FX2N-2LC Temperature Control Block Introduction of Functions 5

5. Introduction of Functions

This section introduces the functions of the FX2N-2LC.

For setting of each function, refer to the description on buffer memories (BFM) later.

5.1 PID control

5.1.1 Easy PID control with two degrees of freedom
PID control is a control method to obtain stable control result by setting each of the constants
"P (proportional band)", "I (integral time)" and "D (derivative time)".
However, if each PID constant is so set that the "response to setting" becomes good, the
"response to disturbance" becomes deteriorated in PID control. On the contrary, if each PID
constant is so set that the "response to disturbance" becomes good, the "response to setting"
becomes deteriorated.
The FX2N-2LC performs easy PID control with two degrees of freedom in which PID constants
realizing good response to disturbance are adopted and the shape of the "response to setting"
can be selected as either "fast", "medium" or "slow". 5
Setting of PID constants and selection of the "response to setting" can be performed using
buffer memories.

Conventional PID control

When PID constants are set so that the response to changes in set value becomes good

Response to changes in set value Response to disturbance

Set value Set value

(SV) (SV)

When PID constants are so set that the response to disturbance becomes good

Response to changes in set value Response to disturbance

Set value Set value

(SV) (SV)

Easy PID control with two degrees of freedom

Response to changes in set value Response to disturbance
Fast
Medium
Set value Set value
(SV) (SV)
Slow

5-1
 FX2N-2LC Temperature Control Block Introduction of Functions 5

5.1.2 Overshoot prevention function

Generally in PID control, when a deviation continues for a long time, the PID arithmetic
operation result exceeds the effective range (from 0 to 100%) of the operation quantity. At this
time, even if the deviation becomes smaller, it takes some time until the output comes within
the effective range because of the integral operation. As a result, execution of an actual
correction operation is delayed, and overshoot/undershoot occurs.
In order to prevent overshoot, the FX2N-2LC is equipped with the RFB (reset-feedback) limiter
function. The RFB limiter function feeds back the excessive quantity to the integral value and
makes the arithmetic operation result be held at the limit point when the PID arithmetic
operation result exceeds the limit point (upper/lower limit of the output limiter) so that the PID
arithmetic operation result always remains inside the effective range. Accordingly, when a
deviation becomes small, the correction operation is immediately performed.

<When the RFB limiter function is not provided> <When the RFB limiter function is provided>
The excessive quantity above the output limiter
upper limit is fed back to the integral value, and
the arithmetic operation result is held at the
upper limit value.
Operation Operation
quantity (%) quantity (%)

Output limiter upper limit Output limiter upper limit

Output limiter lower limit Output limiter lower limit

Temperature Temperature

Target Target
value value

Large overshoot

5-2
 FX2N-2LC Temperature Control Block Introduction of Functions 5

5.2 Two-position control

When the proportional band (P) value is set to "0.0", the FX2N-2LC performs two-position
control.
In two-position control, the control output (MV) is set to ON when the measured value (PV) is
larger than the temperature set value (SV) or OFF when the measured value (PV) is smaller
than the temperature set value (SV).
When the adjustment sensitivity (dead zone) is set, repetitious turning ON/OFF of the output
around the temperature set value (SV) can be prevented.
However, if the adjustment sensitivity (dead zone) is set to a large value, upward/downward
fluctuation becomes large accordingly. If the adjustment sensitivity (dead zone) is set to a
small value, chattering (drastic repetitious turning ON/OFF) may be caused by small
oscillations of measured values.

Temperature 5
set value (SV) Adjustment sensitivity (dead zone)
* The adjustment sensitivity is equally given
to the upper portion and the lower portion
of the temperature set value (SV).

Operation output ON OFF ON OFF

value (MV) Time

5-3
 FX2N-2LC Temperature Control Block Introduction of Functions 5

5.3 Auto tuning function

5.3.1 AT (auto tuning)
The AT (auto tuning) function automatically measures, calculates and sets optimal PID
constants in accordance with the set temperature.
When the AT execution command (CH1: BFM #20, CH2: BFM #29) is set to "1", auto tuning is
performed. (Auto tuning can start from an arbitrary status at any time immediately after the
power is turned ON, while the temperature is rising or while control is stable.)
When auto tuning starts, two-position control is performed using the set value (SV). By two-
position control, the output is forcedly hunted and its amplitude and oscillation cycle are
measured. PID constants are calculated based on the measured values, and stored in each
parameter.
The value is set to each parameter within the range shown below.
Table 5.1:
Applicable parameter Calculated value Value to be set
Proportional band Less than 0.1% 0.1% (0% in version earlier than 1.22)
(BFM #33, #52) 1000.0% or more 1000.0%
Integral time Less than 1 sec. 1 sec.
(BFM #34, #53) 3600 sec. or more 3600 sec.
Derivative time
3600 sec. or more 3600 sec.
(BFM #35, #54)

When auto tuning normally finishes, control continues with new calculated PID constants.
While auto tuning is performed, b14 of the event (CH1: BFM #1, CH2: BFM #2) is set to "1".
For auto tuning, the AT bias can be set.
(In order to calculate proper PID constants by auto tuning, set the upper limit of the output
limiter to 100%, the lower limit of the output limiter to 0%, and the output change ratio limiter
function to OFF.)

Measured value (PV)

(Example: When AT is performed while the temperature is rising)

Temperature
set value (SV)

AT starts. AT finishes.

Time

5-4
 FX2N-2LC Temperature Control Block Introduction of Functions 5

5.3.2 Conditions for performing and aborting AT

1) AT can be performed when all the following conditions are satisfied:
- The control start/stop changeover (BFM #11) set to "1: Starts control".
- The operation mode (BFM #32, #51) set to "2: Monitor + Temperature alarm + Control".
- The auto/manual mode changeover (BFM #18, #27) set to "0: AUTO".
- The measured value PV (BFM #3, #4) is normal.
- The upper limit (BFM #37, #56) and lower limit (BFM 38, #57) of the output limiter should
not be set to the same value.
- The proportional band (BFM #33, #52) setting is not "0.0 (two-position control)".
2) AT is aborted and the 'AT abnormal termination flag (BFM #0 b6:CH1 b7:CH2)' turns ON
during either of the following occurrences:
- The measured value (PV) (BFM #3, #4) becomes abnormal from an incident such as
wire disconnection.
- The set value (SV) (BFM #12, #21) is changed.
- The control start/stop changeover (BFM #11) is set to "0: Stops control".
5
- The input type selection (BFM #70, #71) is changed.
- The auto/manual mode (BFM #18, #27) is set to "1: MAN".
- The operation mode (BFM #32, #51) is set to "0: Monitor" or "1: Monitor + Temperature
alarm".
- The AT bias (BFM #45, #64) is changed.
- The PV bias (BFM #40, #59) is changed.
- The primary delay digital filter setting (BFM #43, #62) is changed.
- The upper (BFM #37, #56) and lower limits (BFM 38, #57) of the output limiter are
changed.
- The proportional band (BFM #33, #52) is set to "0.0 (two-position control)".
- The calculated value of the PID parameters is out of the set range:
Proportional band : 0.1 to 1000.0
Integral time : 1 to 3600
Derivative time : 0 to 3600
- The AT execution command (BFM #20, #29) is set to "0: Stops auto tuning".
(AT abnormal end flag does not turn ON.)
- Power failure occurs. (AT abnormal flag does not turn ON.)

5-5
 FX2N-2LC Temperature Control Block Introduction of Functions 5

5.3.3 AT bias
Set the AT bias to perform auto tuning in which the measured value (PV) should not exceed the
temperature set value (SV).
The auto tuning function performs two-position control using the temperature set value (SV),
hunts the measured value (PV), then calculates and sets each PID constant. However, for
some control targets, overshoot caused by hunting is not desirable. Set the AT bias for such a
case. When the AT bias is set, the set value (SV) (AT point) with which auto tuning is
performed can be changed.

Measured value (PV)

Example: When the AT bias is set to "-"
Temperature
set value (SV)
AT bias
AT point

AT starts. AT finishes.
Time

5-6
 FX2N-2LC Temperature Control Block Introduction of Functions 5

5.4 Auto / manual

5.4.1 Auto mode and manual mode
The mode can be changed over between "auto" and "manual". In the auto mode, the control
output value (MV) is set to the output quantity automatically calculated in accordance with the
temperature set value (SV). In the manual mode, the control output value (MV) is set to the
output quantity set arbitrarily and manually.
In the manual mode, b13 (manual mode transition completion) of the event (CH1: BFM #1,
CH2: BFM #2) becomes "1" to notify the manual mode.
0.5 second is required to change over the mode. During changeover, the balance-less, bump-
less function is actuated.
Auto mode
In the auto mode, the measured value (PV) is compared with the temperature set value (SV),
and the control output (MV) is given by PID arithmetic operation.
This mode is selected when the FX2N-2LC is shipped.
In the auto mode, the manual output value is always set to the output value (MV).
Manual mode
In the manual mode, the output (MV) value is fixed to a certain value. 5
By changing the manual output setting (BFM #19, BFM #28), the output value can be fixed to
an arbitrary value.
The manual output value can be changed while b13 of the event (CH1: BFM #1, CH2: BFM #2)
is "1" (that is, when the manual mode is selected).
Even in the manual mode, the temperature alarm function is effective.
5.4.2 Balance-less, bump-less function
The balance-less, bump-less function prevents overload caused by drastic change in the
control output value (MV) when the mode is changed over from auto to manual (or from
manual to auto).
Operation performed when the mode is changed over from auto to manual:
The control output value in the auto mode continues to be effective.
Operation performed when the mode is changed over from manual to auto:
The control output value is changed over to a value automatically calculated
based on the temperature set value (SV).

Operation output quantity

Auto Manual Auto

Time
➀ ➁ ➂

➀ The mode is changed over from auto to manual. However, the operation output quantity
follows the operation output quantity in the auto mode.
➁ The operation output quantity is manually changed.
➂ The mode is changed over from manual to auto. The operation output quantity becomes
a value automatically calculated based on the temperature set value (SV).

5-7
 FX2N-2LC Temperature Control Block Introduction of Functions 5

5.5 Heater disconnection alarm function

The heater disconnection alarm function detects the current flowing in the load using a current
detector (CT), it compares the detected value (heater current measured value) with the current
value set for heater disconnection alarm, and issues an alarm when the measured value is
more than or less than the current set value for the heater disconnection alarm.
The heater current can be measured using buffer memories (BFM #7, BFM #8).

Connection example
Power supply

Temperature
control block
Control output Operating
machine SSR

FX2N-2LC Current detector

Current detector input

Heater

Measured Sensor
value (PV)
Control target

Alarm operation
The heater disconnection alarm function issues an alarm in the following cases.
1) When the heater current does not flow
... Caused by heater disconnection, error in operating machine, etc.
When the reference heater current value is equivalent to or less than the current set value
for the heater disconnection alarm while the control output is ON, an alarm is issued.
However, if the control output ON time is 0.5 sec or less, heater disconnection alarm func-
tion is not issued.
2) When the heater current does not turn OFF
... Caused by a molten relay, etc.
When the reference heater current value is more than the current set value for the heater
disconnection alarm while the control output is OFF, an alarm is issued.
However, if the control output OFF time is 0.5 sec or less, heater disconnection alarm func-
tion is not issued.

• The current set value for the heater disconnection alarm should be set below the actual
current value of the heater.
Current detector
CTL-12-S36-8 (Applicable current range: 0.0 to 100.0 A)
CTL-6-P-H (Applicable current range: 0.0 to 30.0 A)
Manufacturer: U.R.D. Co., Ltd.

5-8
 FX2N-2LC Temperature Control Block Introduction of Functions 5

5.6 Loop breaking alarm function (LBA)

The loop breaking alarm function starts to detect the variation of the measured value (PV), at
every loop breaking alarm judgment time when the output becomes more than 100% (or the
output limiter upper limit) or less than 0% (or the output limiter lower limit), then sets to ON the
loop breaking alarm (CH1: BFM #1 b8, CH2: BFM #2 b8) when judging that there is an
abnormality in the control loop.
Abnormality judgment criteria
Table 5.2: Heating control (reverse operation)
When measured value (PV) does not decrease at least by loop
When output is less than 0% or
breaking change criteria (2 °C) within loop breaking set time, an
output limiter lower limit
alarm is issued.
When measured value (PV) does not increase at least by loop
When output is more than 100%
breaking change criteria (2 °C) within loop breaking set time, an
or output limiter upper limit
alarm is issued.

Table 5.3: Cooling control (normal operation)

When measured value (PV) does not decrease at leas by loop
5
When output is less than 0% or
breaking change criteria (2 °C) within loop breaking set time, an
output limiter lower limit
alarm is issued.
When measured value (PV) does not increase at least by loop
When output is more than 100%
breaking change criteria (2 °C) within loop breaking set time, an
or output limiter upper limit
alarm is issued.

Abnormality targets
1) Abnormality in control target: Heater disconnection, lack of power supply, wiring mistake,
etc.
2) Abnormality in sensor: Sensor disconnection, short-circuit, etc.
3) Abnormality in operating machine: Molten relay, wiring mistake, etc.
4) Abnormality in output circuit: Molten relay inside instrument, etc.
5) Abnormality in input circuit: No change in the measured value (PV) even after input has
changed
Note:
- When the auto tuning function is used, the LBA set time is automatically set to the
integral time result multiplied by 2.
The LBA set time does not change even if the integral value changes.
- While auto tuning is performed, the loop breaking alarm function is disabled.
- If the LBA set time is too short or is not suitable to control targets, the loop breaking
alarm may repeatedly turn on and off or may not turn ON.
In such a case, change the LBA set time in accordance with the situation.
- The loop breaking alarm function judges abnormalities in the control loop, but cannot
detect positions in which abnormalities occur.
Check each part of the control system in turn.

5-9
FX2N-2LC Temperature Control Block Introduction of Functions 5

MEMO

5-10
FX2N-2LC Temperature Control Block Alarm 6

1 Introduction

2 Product Configuration

3 Specifications

4 Wiring

5 Introduction of Functions

6 Alarm 6

7 Buffer Memory (BFM)

8 Program Example

9 Diagnostic
FX2N-2LC Temperature Control Block Alarm 6
FX2N-2LC Temperature Control Block Alarm 6

6. Alarm

The FX2N-2LC is equipped with 14 types of alarms. Among them, up to 4 types can be used in
accordance with the application.
The alarm types to be used can be selected using buffer memories. The result of each alarm
is written to BFM #1 and BFM #2, and can be read in the PLC main unit.
When the measured value (PV) is near the alarm set value of an used alarm type, the alarm
status and the non-alarm status may be repeated by fluctuation in inputs. In order to cope with
such a case, the alarm dead zone can be set to prevent repeating of the alarm status and the
non-alarm status. (The dead zone of alarms 1 to 4 can be set using BFM #76.)
Table 6.1:
Alarm Set
Alarm type Description
No. range
0 Alarm function OFF Alarm function is disabled. ---
When measured value (PV) is more than alarm set Input
1 Upper limit input value alarm
value, an alarm is issued. range
When measured value (PV) is less than alarm set Input
2 Lower limit input value alarm
value, an alarm is issued. range
When deviation (= Measured value (PV) - Set
±Input
3 Upper limit deviation alarm value (SV)) is more than alarm set value, an alarm
is issued.
width 6
When deviation (= Measured value (PV) - Set
±Input
4 Lower limit deviation alarm value (SV)) is less than alarm set value, an alarm
width
is issued.
When absolute deviation (= ⏐Measured value (PV)
+Input
5 Upper/lower limit deviation - Set value (SV)⏐) is more than alarm set value, an
width
alarm is issued.
When absolute deviation (= ⏐Measured value (PV)
+Input
6 Range alarm - Set value (SV)⏐) is less than alarm set value, an
width
alarm is issued.
When measured value (PV) is more than alarm set
Upper limit input value alarm Input
7 value, an alarm is issued. However, when power is
with wait range
turned ON, measured value is ignored.
When measured value (PV) is less than alarm set
Lower limit input value alarm Input
8 value, an alarm is issued. However, when power is
with wait range
turned ON, measured value is ignored.
When deviation (= Measured value (PV) - Set
Upper limit deviation value value (SV)) is more than alarm set value, an alarm ±Input
9
alarm with wait is issued. However, when power is turned ON, width
measured value is ignored.
When deviation (= Measured value (PV) - Set
Lower limit deviation value value (SV)) is less than alarm set value, an alarm ±Input
10
alarm with wait is issued. However, when power is turned ON, width
measured value ignored.
When absolute deviation (= ⏐Measured value (PV)
Upper/lower limit deviation - Set value (SV)⏐) is more than alarm set value, an +Input
11
value alarm with wait alarm is issued. However, when power is turned width
ON, measured value is ignored.

6-1
FX2N-2LC Temperature Control Block Alarm 6

Table 6.1:
Alarm Set
Alarm type Description
No. range
When deviation (= Measured value (PV) - Set
value (SV)) is more than alarm set value, an alarm
Upper limit deviation value ±Input
12 is issued. However, when power is turned ON and
alarm with re-wait width
when set value is changed, measured value is
ignored.
When deviation (= Measured value (PV) - Set
value (SV)) is less than alarm set value, an alarm
Lower limit deviation value ±Input
13 is issued. However, when power is turned ON and
alarm with re-wait width
when set value is changed, measured value is
ignored.
When absolute deviation (= ⏐Measured value (PV)
- Set value (SV)⏐) is more than alarm set value, an
Upper/lower limit deviation +Input
14 alarm is issued. However, when power is turned
value alarm with re-wait width
ON and when set value is changed, measured
value is ignored.
Input range:Numeric value from the lower limit to the upper limit of input value
Input width:Width from the lower limit to the upper limit of input value (Input width = Upper limit
value - Lower limit value)
± Input width ...Both a positive and negative numeric values can be set.
+ Input width ...Only a positive numeric value can be set.

6-2
FX2N-2LC Temperature Control Block Alarm 6

Upper limit input value alarm

When the measured value (PV) is more than the alarm set value, an alarm is issued.

Measured value (PV) Measured value (PV)

Alarm set value

Time
Non-alarm status
Alarm status
Alarm status

Lower limit input value alarm

When the measured value (PV) is less than the alarm set value, an alarm is issued.

Measured value (PV)

Measured value (PV)

Alarm set value

6

Time
Non-alarm status
Alarm status Alarm status

Upper limit deviation alarm

When the deviation (= Measured value (PV) - Set value (SV)) is more than the alarm set value,
an alarm is issued.

< When the deviation is positive > < When the deviation is negative >
Measured value Measured value
(PV) Measured value (PV)
(PV) Measured value
(PV)
Alarm set Temperature
value Devia set value (SV) Devia
Temperature tion Alarm set tion
set value (SV) value

Time Time
Alarm status Alarm status

Non-alarm Alarm
status status

6-3
FX2N-2LC Temperature Control Block Alarm 6

Lower limit deviation alarm

When the deviation (= Measured value (PV) - Set value (SV)) is less than the alarm set value,
an alarm is issued.
< When the deviation is positive > < When the deviation is negative >
Measured value Measured value Measured value
(PV) (PV) (PV) Measured value
(PV)
Alarm set Temperature
value Devia set value (SV) Devia
Temperature tion tion
set value (SV) Alarm set value

Time Time
Alarm status Alarm status

Non-alarm Alarm
status status

Upper/lower limit deviation alarm

When the absolute deviation (= ⏐Measured value (PV) - Set value (SV)⏐) is more than the
alarm set value, an alarm is issued.
For example, if the alarm set value is "+10 °C", an alarm is issued when the measured value
(PV) is outside the range from "set value (SV) + 10 °C" to "set value (SV) - 10 °C".

Measured value (PV)

Measured value (PV)
Alarm set
value
Deviation
Temperature
set value (SV)
Deviation
Alarm set
value

Time
Non-alarm status
Alarm status Alarm status

Range alarm
When the absolute deviation (= ⏐Measured value (PV) - Set value (SV)⏐) is less than the alarm
set value, an alarm is issued.
For example, if the alarm set value is "+10 °C", an alarm is issued when the measured value
(PV) is inside the range from "set value (SV) + 10 °C" to "set value (SV) - 10 °C".

Measured value (PV)

Measured value (PV)
Alarm set
value
Deviation
Temperature
set value (SV)
Deviation
Alarm set
value

Time
Non-alarm status
Alarm status Alarm status

6-4
FX2N-2LC Temperature Control Block Alarm 6

Alarm wait operation

The wait operation ignores the alarm status of the measured value (PV) occurred when the
power is turned ON, and disables the alarm function until the measured value (PV) goes out of
the alarm status once.
When control starts, the wait operation is performed also.

< When the wait operation is performed > < When the wait operation is not performed >
Measured value (PV) Measured value (PV)
Measured value Measured value
(PV) (PV)
Temperature Temperature
set value (SV) Devia set value (SV) Devia
Alarm set tion Alarm set tion
value value

Time Time
Alarm status
Wait operation region

Alarm status Non-alarm Alarm

status status

Alarm re-wait operation

The alarm re-wait operation ignores the alarm status of the measured value (PV) occurred 6
when the power is turned ON, and disables the alarm function until the measured value (PV)
goes out of the alarm status once.
When the temperature set value (SV) is changed, the measured value (PV) for deviation alarm
changes accordingly. At this time, even if the measured value (PV) becomes the alarm status,
the alarm re-wait function ignores it again and disables the alarm function until the measured
value (PV) goes out of the alarm status again.

Re-wait operation

Measured value (PV) Measured value (PV)

Temperature set
value (SV) Deviation
Alarm set value
Set value is changed.
Temperature set
value (SV1) Deviation
Alarm set value

Time
Wait operation region Wait operation region Non-alarm
status
Alarm status Alarm status

6-5
FX2N-2LC Temperature Control Block Alarm 6

MEMO

6-6
FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

1 Introduction

2 Product Configuration

3 Specifications

4 Wiring

5 Introduction of Functions

6 Alarm

7 Buffer Memory (BFM) 7

8 Program Example

9 Diagnostic
FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7
 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7. Buffer Memory (BFM)

Each setting and alarm in the FX2N-2LC is written from or read to the PLC main unit through
buffer memories (hereafter referred to as "BFM").
Each BFM consists of 16 bits. Use FROM/TO instructions in the 16-bit format.

7.1 Buffer memory list

Table 7.1:
BFM No. Initial
Name Description/set range Remarks
CH1 CH2 value
#0 Flag Error flag, ready flag, etc. 0 ---
Alarm status, temperature rise
#1 #2 Event 0 ---
completed status, etc.
R
#3 #4 Measured value (PV) ±5% of input range (°C/°F) 0.0 ■
#5 #6 Control output value (MV) -5.0 to 105.0 (%) -5.0 ▲
#7 #8 Heater current measured value 0.0 to 105.0 (A) 0.0 ▲
---
0: Performs nothing
#9 Initialization command 1: Initializes all data 0 ---
2: Initializes BFM #10 to BFM #69
0: Performs nothing
#10 Error reset command 0 ---
1: Resets errors
0: Stops control
#11 Control start/stop changeover 0 ---
1: Starts control 7
#12 #21 Set value (SV) Within set range limiter 0.0 ■
#13 #22 Alarm 1 set value 0.0 ■
Unit: °C or °F
#14 #23 Alarm 2 set value Allowable set range varies 0.0 R/W ■
#15 #24 Alarm 3 set value depending on alarm mode 0.0 ■
setting.
#16 #25 Alarm 4 set value 0.0 ■

Heater disconnection alarm set

0.0 to 100.0 A ✩
#17 #26 (When "0.0" is set, alarm function 0.0 ▲
value
is disabled.)
#18 #27 Auto/manual mode changeover 0:AUTO 1:MAN 0
#19 #28 Manual output set value -5.0 to 105.0 (%) *1 0.0 ▲
0: Stops auto tuning
#20 #29 Auto tuning execution command 0 ---
1: Performs auto tuning
#30 Unit type code 2060 R ---
---
#31 Prohibited --- --- --- ---
0: Monitor
1: Monitor + Temperature alarm
#32 #51 Operation mode 2 ---
2: Monitor + Temperature alarm +
Control
0.0 to 1,000.0 (% of input span) R/W ✩
#33 #52 Proportional band (When "0.0" is set, two-position 3.0 ▲
control is performed.)
#34 #53 Integral time 1 to 3,600 sec 240 ---
#35 #54 Derivative time 0 to 3,600 sec 60 ---

7-1
FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

Table 7.1:
BFM No. Initial
Name Description/set range Remarks
CH1 CH2 value
#36 #55 Control response parameter 0: Slow 1: Medium 2: Fast 0 ---
Output limiter lower limit to 105.0
#37 #56 Output limiter upper limit 100.0 ▲
(%)
#38 #57 Output limiter lower limit -5.0% to output limiter upper limit 0.0 ▲
0.0 to 100.0 %/sec
#39 #58 Output change ratio limiter (When "0.0" is set, function is 0.0 ▲
disabled.)
Sensor correction value setting
#40 #59 ±50.00 (% of input span) 0.00 ▲
(PV bias)
Adjustment sensitivity (dead
#41 #60 0.0 to 10.0 (% of input span) 1.0 ▲
zone) setting
#42 #61 Control output cycle setting 1 to 100 sec 30 ---
0 to 100 sec
Primary delay digital filter
#43 #62 (When "0" is set, function is 0 ---
setting
disabled.)
0.0 to 100.0 %/min
#44 #63 Setting change ratio limiter (When "0.0" is set, function is 0.0 ▲
disabled.)
#45 #64 AT (auto tuning) bias ±Input span (°C/°F) 0.0 ■
Normal/reverse operation 0: Normal operation
#46 #65 1 ---
selection 1: Reverse operation
Setting limiter lower limit to input
#47 #66 Setting limiter upper limit 1300 R/W ✩ ■
range upper limit
Input range lower limit to setting
#48 #67 Setting limiter lower limit -100 ■
limiter upper limit
0 to 7,200 sec
Loop breaking alarm judgement
#49 #68 (When "0" is set, alarm function is 480 ---
time
disabled.)
#50 #69 Loop breaking alarm dead zone 0.0 or 0 to input span (°C/°F) 0.0 ■
#70 #71 Input type selection 0 to 43 2 ---
#72 Alarm 1 mode setting 0 ---
#73 Alarm 2 mode setting 0 ---
0 to 14
#74 Alarm 3 mode setting 0 ---
#75 Alarm 4 mode setting 0 ---
#76 Alarm 1/2/3/4 dead zone setting 0.0 to 10.0 (% of input span) 1.0 ▲
Number of times of alarm 1/2/3/
#77 0 to 255 times 0 ---
4 delay
Number of times of heater
#78 3 to 255 times 3 ---
disconnection alarm delay
Temperature rise completion
#79 Integer 1 to 10 (°C/°F) 10 ---
range setting
Temperature rise completion
#80 0 to 3600 (sec) 0 ---
soak time

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FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

Table 7.1:
BFM No. Initial
Name Description/set range Remarks
CH1 CH2 value
0: Monitors both ON current and
#81 CT monitor method changeover OFF current. 0 R/W ---
1: Monitors only ON current.
0: Normal
✩
#82 Set value range error address 1 or another numeric value : 0 R ---
Setting error address
0: Normal
#83 Set value backup command 0 R/W ---
1: Starts to write EEPROM.
R : Only read is enabled.
R/W : Both read and write are enabled.
✩ : Setting data can be backed up by EEPROM in accordance with the setting of BFM #83.
*1 : Write is enabled when the manual mode transition completion flag is ON.
■ : Handling numbers containing decimal places
The set value should be the actual value multiplied by ten (multiplied by 100 for BFM #40
and #59).
Example: 100.0 (actual value) → 1000 (set value)
▲ : Handling integers or numbers containing decimal places according to the input sensor
type (setting of BFM #70 and #71).
When handling numbers containing decimal places, multiply the set value by ten.
7
- As to a numeric value containing a decimal point and numbers after that, set it as a value
multiplied by 10.
Example: 100.0 (actual value) → 1000 (set value)
- If a value is written by mistake to a buffer memory used only for read, the written value is
ignored. And 500 ms later, the buffer memory is overwritten with a correct value.
- If a value outside the allowable set range is written to a buffer memory used both for read
and write, the set value range error (b1) of the flag (BFM #0) turns ON.
And the buffer memory in which the set value range error has occurred is controlled with
the upper limit or the lower limit of the allowable set range.

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 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2 Details of buffer memories

7.2.1 BFM #0: Flag
Table 7.2:
Bit No. Description Operation
Turns ON when an error among b1 to b10 below has
b0 Error present
occurred.
b1 Set value range error Turns ON when data outside set range is written.
Turns ON when driving power supply (24 VDC) is not
b2 24 VDC power supply error
supplied.
Turns ON when an error has been caused by noise or when
a failure has occurred in FX2N-2LC.
b3 Set value backup error If contents of error are not eliminated even after power is
turned OFF once then ON again, contact Mitsubishi Electric
System Service.
b4 Unused ---
b5 Unused ---
AT abnormal end flag (CH1)
b6
(Applicable to Ver. 1.22 or later) Each bit turns ON when AT abnormally ends.
The alarm can be reset by set a value of 0 to the AT
AT abnormal end flag (CH2) execution command. See Ch. 5.3.
b7
(Applicable to Ver. 1.22 or later)
Sum check error for adjustment Turns ON when an error has been caused by noise or when
b8
data error a failure has occurred in FX2N-2LC.
Cold contact temperature If contents of error are not eliminated even after power is
b9
compensation data error turned OFF once then ON again, contact Mitsubishi Electric
b10 A/D converted value error System Service.
b11 Unused ---
b12 Controlling flag Turns ON when FX2N-2LC is performing control.
Remains ON while set values are being backed up.
b13 Set value being backed up
Refer to 7.2.42.
b14 Unused ---
b15 Temperature control ready flag Turns ON when FX2N-2LC becomes ready for operation.

Operation of b15 (Temperature control ready flag)

Temperature control ready flag

Power is turned ON. Temperature control CPU

It takes 500 ms ready for operation.
maximum.

Description on operation
1) Once the power has been turned ON the FX2N-2LC is ready.
Temperature control ready flag turns ON.
2) While the temperature control ready flag is ON, the FX2N-2LC accepts TO instructions.
3) The measured data is sampled for nine seconds after the temperature control ready flag
turns ON and then stored in BFM #12 and #21.
During this period of time, the ON/OFF operation is not executed.

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 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.2 BFM #1 (CH1) and BFM #2 (CH2): Event

BFM #1 corresponds to CH1. BFM #2 corresponds to CH2. Assignment is equivalent between
BFM #1 and BFM #2.
Table 7.3:
Bit No. Assignment Description
b0 Input error (upper limit) Turns ON when input value is over scale.
b1 Input error (lower limit) Turns ON when input value is under scale.
Cold contact temperature Turns ON when an error has been caused by noise or when
b2
compensation data error a failure has occurred in FX2N-2LC.
If contents of error are not eliminated even after power is
b3 A/D converted value error turned OFF once then ON again, contact Mitsubishi Electric
System Service.
b4 Alarm 1 Turns ON when an alarm has occurred.
b5 Alarm 2 Turns ON when an alarm has occurred.
b6 Alarm 3 Turns ON when an alarm has occurred.
b7 Alarm 4 Turns ON when an alarm has occurred.
b8 Loop breaking alarm Turns ON when a loop breaking alarm has occurred
b9 Heater disconnection alarm Turns ON when a heater disconnection alarm has occurred.
b10 Heater meltdown alarm Turns ON when a heater meltdown alarm has occurred.
Output ON/OFF monitor
b11 Turns ON/OFF according to the output status.
(Applicable to Ver. 1.22 or later)
Decimal point position
b12 (0: Unit = 1°C/°F, 1: Unit = 0. Turns ON when input range is set to "0. 1°C/°F". 7
1°C/°F)
Turns ON when transition to manual mode is completed.
Manual mode transition
b13 Only while b13 is ON, manual output set value can be
completed
written.
AT (auto tuning) being
b14 Remains ON while auto tuning is being performed.
performed
Temperature rise completed Turns ON after soak time (BFM #80) is finished within
b15
status temperature rise completion range (BFM #79).

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FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

Operation of b15 (temperature rise completed status)

Example 1: When the soak time is set to "0"

Set value (SV)

Temperature rise
completion range

Temperature
rise completed

Example 2: When the soak time is set to any positive value

Set value (SV)

Temperature rise
Soak Soak completion range
time time

Temperature
rise completed

This bit notifies that the measured value (BFM #3, BFM #4) reaches near the set value (BFM
#12, BFM #21).
When the measured value reaches the temperature rise completion range (BFM #79) and the
soak time (BFM #80) is finished, b15 of the event (BFM #1, BFM #2) turns ON.

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 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.3 BFM #3 (CH1) and BFM #4 (CH2): Measured value (PV)

BFM #3 stores the measured value for CH1. BFM #4 stores the measured value for CH2.
The units are °C, 0.1°C, °F or 0.1°F in accordance with the setting of the input type selection
(BFM #70, BFM #71).
When the power is turned ON, the measured value is stored in each of the mentioned BFMs
after nine seconds of sampling time.

7.2.4 BFM #5 (CH1) and BFM #6 (CH2): Control output value (MV)
BFM #5 stores the control output value (output ON ratio) of CH1. BFM #6 stores the control
output value (output ON ratio) of CH2.
The display range is from -5.0 to +105.0%.

7.2.5 BFM #7 (CH1) and BFM #8 (CH2): Heater current measured value
BFM #7 stores the heater current measured value of CH1 input from CT. BFM #8 stores the
heater current measured value of CH2 input from CT.
The display range is from 0.0 to +105.0 A.

7.2.6 BFM #9: Initialization command

In BFM #9, initialize the set values.
When BFM #9 is set to "K0 (initial value)", the initialization command is disabled.
When BFM #9 is set to "K1", addresses 10 to 81 are set to the initial values.
When BFM #9 is set to "K2", addresses 10 to 69 are set to the initial values.
7
- When BFM #9 is set to "K1" or "K2", initialization is completed and BFM #9 retains a
value of "K0" automatically.
- The initial value of the setting limiter's upper/lower limits are the input range's upper/
lower limits.
- Initialization takes 500 ms maximum. Do not activate FROM/TO instructions on the BFM
being initialized.

7.2.7 BFM #10: Error reset command

In BFM #10, reset errors.
When BFM #10 is set to "K1", all errors occurred in BFM #0 are reset.
If the causes of an error are not eliminated, the corresponding error bit turns ON again.
The error reset command is not automatically set when another error has occurred. Thus, set
BFM #10 to "K0" once again. (In order to execute the error reset command, set BFM #10 to
"K1" for 0.5 seconds or longer.)

7.2.8 BFM #11: Control start/stop changeover

When BFM #11 is set to "K0 (initial value)", control stops.
When BFM #11 is set to "K1", control starts.
When the PLC main unit is changed over from "RUN" to "STOP", outputs of the FX2N-2LC are
held.
In order to stop outputs of the FX2N-2LC, make sure to use BFM #11.

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 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.9 BFM #12 (CH1) and BFM #21 (CH2) : Set value (SV)
BFM #12 stores the set value of CH1. BFM #21 stores the set value of CH2.
The unit is ° C, 0.1°C, °F or 0.1°F in accordance with the setting of the input type selection
(BFM #70, BFM #71).
The allowable set range is the selected input range.
When the setting limiter (CH1: BFM #47 and BFM #48, CH2: BFM #66 and BFM #67) is set,
the allowable set range corresponds to the setting limiter.

7.2.10 BFM #13 to BFM #16 (CH1) and BFM #22 to BFM #25 (CH2): Alarm 1/2/3/4 set value
In BFM #13 to BFM #16 and BFM #22 to BFM #25, write the set value of each alarm selected
by the alarm 1/2/3/4 mode setting (BFM #72 to BFM #75).
In the alarm 1/2/3/4 mode setting, four among 14 alarm types can be arbitrarily selected.
BFM #13 to BFM #16 (CH1) and BFM #22 to BFM #25 (CH2) are assigned to the alarm 1
mode, the alarm 2 mode, the alarm 3 mode and the alarm 4 mode respectively in the
ascending order of BFM No. for each channel.
The unit and the allowable range of the set value written to BFM #13 to BFM #16 (CH1) and
BFM #22 to BFM #25 (CH2) vary depending on the selected alarm mode. In accordance with
the setting of the alarm mode setting (BFM #72 to BFM #75), write a proper set value.

7.2.11 BFM #17 (CH1) and BFM #26 (CH2): Heater disconnection alarm set value
In BFM #17, set a value to recognize heater disconnection in CH1. In BFM #26, set a value to
recognize heater disconnection in CH2.
Depending on the output ON/OFF status, the heater's current value for each channel input
from the CT and the value set for BFM #17 (CH1) or BFM #26 (CH2), thus, heater
disconnection alarm (CH1: BFM #1 b9, CH2: BFM #2 b9) turns ON.
The display range is from 0.0 to 100.0 A.
When BFM #17/#26 is set to "0.0", the heater disconnection alarm function is disabled.
The current set value for the heater disconnection alarm should be set below the actual current
value of the heater.

7.2.12 BFM #18 (CH1) and BFM #27 (CH2) : Auto/manual mode changeover
In BFM #18, change over the mode of CH1. In BFM #27, change over the mode of CH2.
When BFM #18/#27 is set to "K0 (initial value)", the auto mode is selected.
When BFM #18/#27 is set to "K1", the manual mode is selected.
Auto mode:
The measured value (PV) is compared with the temperature set value (SV), PID arithmetic
operation is performed, then the control output (MV) is given.
In the auto mode, the manual output set value (CH1: BFM #19, CH2: BFM #28) is always
equivalent to the control output value.
Manual mode:
The control output (MV) value is fixed to the manual output set value (CH1: BFM #19, CH2:
BFM #28).
The manual output set value can be changed while b13 of the event (CH1: BFM #1, CH2: BFM
#2) is ON even if operation is performed in the manual mode.
The temperature alarm function is effective even in the manual mode.

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 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.13 BFM #19 (CH1) and BFM #28 (CH2): Manual output set value
In BFM #19 (CH1) and BFM #28 (CH2), set the output ON ratio in the manual mode.
The display range is from -5.0 to +105.0%.
The output ON/OFF cycle (period of time) can be set within the range from 1 to 100 sec using
BFM #42 (CH1) and BFM #61 (CH2).
Write the percentage of the ON period of time.

7.2.14 BFM #20 (CH1) and BFM #29 (CH2): Auto tuning execution command
In BFM #20, perform auto tuning of CH1. In BFM #29, perform auto tuning of CH2.
When BFM #20/#29 is set to "K0", auto tuning is stopped.
When BFM #20/#29 is set to "K1", auto tuning is performed.
In order to execute AT again, set BFM #20 and #29 to "K0" after the initial AT is completed (b14
of both BFM #1 and #2 turns OFF) and then set once more to "K1".

7.2.15 BCM#30: Unit type code

BFM #30 stores the unit type code "2060 (fixed value)" of the FX2N-2LC.

7.2.16 BFM #32 (CH1) and BFM #51 (CH2): Operation mode
In BFM #32, select the operation mode of CH1. In BFM #51, select the operation mode of
CH2.
When BFM #32/#51 is set to "K0", only monitor is performed. (At this time, the control output
remains OFF.) 7
When BFM #32/#51 is set to "K1", monitor and temperature alarm are performed. (At this time,
the control output remains OFF.)
When BFM #32/#51 is set to "K2 (initial value)", all of monitor, temperature alarm and control
are performed.
- Monitor: Monitors the measured value (BFM #3/#4).
Temperature alarm: Monitors the event input error (b0 and b1 of BFM #1 and BFM #2)
and alarms 1 to 4 (b4 to b7 of BFM #1 and BFM #2).
Control: Performs temperature control (PID control) and gives the control output.
- The setting of "K0" to "K2" above is effective only when control starts (BFM #11).
While control is stopped, only monitor is performed without regard to the setting
described above.

7.2.17 BFM #33 (CH1) and BFM #52 (CH2): Proportional band (P)
In BFM #33, set the proportional band of CH1. In BFM #52, set the proportional band of CH2.
The proportional band is required to give the control output in proportion to the deviation
(which is the difference between the set value (SV) and the measured value (PV)).
As the proportional band value is larger, changes in the control output value (MV) in response
to changes in the input is smaller. On the contrary, as the proportional band value is smaller,
changes in the control output value (MV) in response to changes in the input is larger.
(Generally, the proportional band is the inverse number of the proportional gain.)
However, if the proportional band value is too large, overshoot becomes large and it takes
considerable time until the output is stabilized at the set value.
The allowable set range is from 0.0 to 1,000.0%.
When BFM #33/#52 is set to "0.0", two-position control is performed.

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 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.18 BFM #34 (CH1) and BFM #53 (CH2): Integral time (I)
In BFM #34, set the integral time of CH1. In BFM #53, set the integral time of CH2.
The integral operation changes the operation quantity in proportion to the area enclosed by the
deviation size and the period of time in which deviation is generated.
In the proportional operation, even while the operation quantity is stable, deviation (which is the
difference between the set value (SV) and the measured value (PV)) may be caused by natural
radiation, etc. The integral operation eliminates such a deviation. At this time, the period of
time required to obtain, only by the integral operation, the operation quantity equivalent to that
obtained by the proportional operation is called the integral time.
As the integral time is shorter, the integral efficiency is better.
The allowable set range is from 0 to 3,600 sec.

7.2.19 BFM #35 (CH1) and BFM #54 (CH2): Derivative time (D)
In BFM #35, set the derivative time of CH1. In BFM #54, set the derivative time of CH2.
The derivative operation changes the operation quantity in proportion to the measured value
change speed so that increase of deviation (which is the difference between the set value (SV)
and the measured value (PV)) can be prevented from happening.
Because the derivative operation responds to the measured value change ratio, the response
to disturbances (turbulence in the measured value caused by external factors) is improved.
When the deviation increases or decreases at a constant ratio, the period of time required to
obtain, only by the derivative operation, the operation quantity equivalent to that obtained by
the proportional operation is called the derivative time.
As the derivative time is longer, the derivative effect is larger.
The allowable set range is from 0 to 3,600 sec.
When BFM #35/#54 is set to "0", the derivative function is disabled.

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 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.20 BFM #36 (CH1) and BFM #55 (CH2): Control response parameter
In BFM #36, set the control response parameter of CH1. In BFM #55, set the control response
parameter of CH2.
The control response parameter selects the response to changes in the temperature set value
(SV) in PID control among three steps (slow, medium and fast).
When BFM #36/#55 is set to "K0", the response becomes slow speed.
When BFM #36/#55 is set to "K1", the response becomes medium speed.
When BFM #36/#55 is set to "K2", the response becomes fast speed.
The figure below shows the operation at each setting.

Measured value (PV)

Fast
Medium

Temperature
set value (SV) 2

Changed
Slow
Temperature set
value (SV) 1

7
Time
Temperature set value (SV)
change point

In order to increase the response speed of the control target to changes in the temperature set
value (SV), select "fast".
In this case, however, a little overshoot cannot be avoided.
Overshoot is not desirable in some control targets. In order to prevent overshoot, select "slow".

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 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.21 BFM #37 (CH1) and BFM #56 (CH2): Output limiter upper limit
BFM #38 (CH1) and BFM #57 (CH2): Output limiter lower limit
In BFM #37 and BFM #56, set the output limiter upper limit of CH1 and CH2 respectively. In
BFM #38 and BFM #57, set the output limiter lower limit of CH1 and CH2 respectively.
Use these BFMs when setting the upper limit and the lower limit for the setting of the control
output value (MV) (BFM #5, BFM #6).
The allowable set range of the upper limit is from the output limiter lower limit to +105%. The
allowable set range of the lower limit is from -5.0% to the output limiter upper limit.

100%
Output limiter
(upper limit)

MV

Output limiter
(lower limit)
0%

- While the output limiter is effective, proper PID constants may not be obtained during
auto tuning.
It is recommended not to use the output limiter when auto tuning is used.
- While two-position control is used, the output limiter is not effective.

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 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.22 BFM #39 (CH1) and BFM #58 (CH2): Output change ratio limiter
In BFM #39, set the output change ratio limiter of CH1. In BFM #58, set the output change
ratio limiter of CH2.
The output change ratio limiter function limits the variation of the control output value (MV) per
unit time (1 sec). The output is limited in accordance with the preset output change ratio.
The allowable set range is from 0 to 100%.
When BFM #39/#58 is set to "0.0%", the output change ratio limiter function is disabled.

When the output change ratio limiter is not used

Output limiter (upper limit)

Operation output value
(MV)
0.1 to
Output 100.0%
drastically
changes. 1 sec
Operation output value
(MV)
Output limiter (lower limit) Set how many percentages the
operation output is to be
changed in a second.
Drastic changes in output
caused by power ON, change of
the set value, disturbance, etc.

When the power is turned ON (outside the proportional band) or when the set value is
considerably changed, the output does not drastically change but is performed in accordance 7
with the preset inclination.
- When the output change ratio limiter is set to a small value (that is, when the inclination
is small), the control response becomes slow and the effect of differential is eliminated.
- While two-position control is performed, the output change ratio limiter is disabled.
- While the output change ratio limiter is effective, proper PID constants may not be
obtained during auto tuning. It is recommended not to use the output change ratio limiter
when auto tuning is used.

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 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.23 BFM #40 (CH1) and BFM #59 (CH2): Sensor correction value setting (PV bias)
In BFM #40, set the sensor correction value of CH1. In BFM #59, set the sensor correction
value of CH2.
The actual input value is added (corrected) by the sensor correction value, then stored as the
measured value (BFM #3, BFM #4).
Use this correction value to correct the dispersion among sensors and the difference in the
measured value (PV) from those by other instruments.
The allowable set range is ±50.00%.
Example
Condition: To correct 2 °C in the range span of 400 °C
At this time, the sensor correction value is as follows.
Sensor correction value = 2 °C / 400 °C x 100 = 0.5%
The display value is as follows.
Display value = Measured value (PV) + Sensor correction value

Measured value (PV) Correction value:2°C

Display
Temperature value
set value
(SV) Actual measured value

Time

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 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.24 BFM #41 (CH1) and BFM #60 (CH2): Adjustment sensitivity (dead zone) setting
In BFM #41, set the adjustment sensitivity (dead zone) of CH1. In BFM #60, set the
adjustment sensitivity (dead zone) of CH2.
By setting the adjustment sensitivity, repetitious turning ON/OFF of the output around the
temperature set value (SV) can be prevented while two-position control is performed.
The value set to BFM #41/#60 is equally given to the upper portion and the lower portion of the
temperature set value (BFM #12/#21). (For example, if the adjustment sensitivity value is set
to "10%", 5% above the temperature set value and 5% below the temperature set value are
treated as the dead zone (width of 10% in total).
The allowable set range is from 0.0 to 10.0%.

Example
Condition: When BFM #41/#60 is set to "10.0%" in the range span of 400 °C
400 °C x 10.0% / 100 = 40 °C
When the temperature set value is 200 °C, the range from 180 to 220 °C is treated as the dead
zone.

Temperature Adjustment sensitivity (dead zone)

set value (SV)
* The adjustment sensitivity setting
is given to both the upper portion
and the lower portion of the
temperature set value (SV). 7

ON OFF ON OFF
Control output Time
value (MV)

When the adjustment sensitivity (dead zone) is set to a large value, vertical fluctuation
becomes large.
When the adjustment sensitivity is too small, small oscillations of the measured value cause
chattering.

7.2.25 BFM #42 (CH1) and BFM #61 (CH2): Control output cycle setting
In BFM #42, set the control output cycle of CH1. In BFM #61, set the control output cycle of
CH2.
Set the period of time in which the output turns ON and OFF.
The value set here multiplied by the control output value (%) is treated as the ON time. The
value set here multiplied by "100 - Control output value (%)" is treated as the OFF time.
The allowable set range is from 1 to 100 sec.

ON OFF
Control output

Control output cycle

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 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.26 BFM #43 (CH1) and BFM #62 (CH2): Primary delay digital filter setting
In BFM #43, set the primary delay digital filter of CH1. In BFM #62, set the primary delay
digital filter of CH2.
The FX2N-2LC is equipped with the software input filter so that fluctuation of the measured
value (PV) caused by noise can be reduced. The time constant of this input filter can be set in
accordance with the characteristics of the control target and the noise level.
If the time constant is too small, the input filter cannot give required effect. If the time constant
is too large, the input responsibility is deteriorated.
The allowable set range is from 0 to 100 sec. When BFM #43/#62 is set to "0", the filter
function is disabled.
While the filter function is disabled, data is acquired in the sampling cycle (500 ms).

Input of actual measured value (PV) Pulse input caused by noise

Input of measured value (PV) processed

by the primary delay digital filter
Input amplitude
Amplitude
processed by
the filter

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 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.27 BFM #44 (CH1) and BFM #63 (CH2): Setting change ratio limiter
In BFM #44, set the setting change ratio limiter of CH1. In BFM #63, set the setting change
ratio limiter of CH2.
The setting change ratio limiter function changes step by step the difference in the temperature
set value when the temperature set value is changed.
Set the variation (%) per minute.
The allowable set range is from 0.1 to 100.0%.
When BFM #44/#63 is set to "0", the setting change ratio limiter function is disabled and the
set value immediately changes.

Example
When the temperature set value 1 (SV1) is changed to the temperature set value 2 (SV2)

(When the set value is changed to a larger value)

SV2
SV
0.0 to
100.0%
of span
SV
1 min

SV2
Set by how many percentages
7
of the span the set value is to
increase in a minute.
The set value is
changed.

- When the power is turned ON, the PV changes to the SV step by step if the change ratio
limiter function is used. (When the setting change ratio limiter function is used.)
- When the alarm function is used, the alarm wait function is not performed while the PV is
changing to the SV step by step.

7-17
 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.28 BFM #45 (CH1) and BFM #64 (CH2): AT (auto tuning) bias
In BFM #45, set the AT (auto tuning) bias of CH1. In BFM #64, set the AT (auto tuning) bias of
CH2.
The allowable set range is ± input range span (°C / °F).
Set the AT bias for control targets in which the measured value (PV) should not exceed the
temperature set value (SV) while auto tuning is performed.
The auto tuning function performs two-position control using the temperature set value (SV),
hunts the measured value (PV), then calculates and sets each PID constant. However, for
some control targets, overshoot caused by hunting is not desirable. Set the AT bias for such a
case. When the AT bias is set, the set value (SV, AT point) with which auto tuning is performed
can be changed.

Measured value (PV)

Example: When the AT bias is set to "-"
Temperature
set value (SV)
AT bias
AT point

AT starts. AT finishes.
Time

7.2.29 BFM #46 (CH1) and BFM #65 (CH2): Normal/reverse operation selection
In BFM #46, select the normal or reverse operation of CH1. In BFM #65, select the normal or
reverse operation of CH2.
When BFM #46/#65 is set to "K0", normal operation is selected.
When BFM #46/#65 is set to "K1 (initial value)", reverse operation is selected.
Table 7.4:
Normal operation (0) When actual temperature is higher than set value To control cooling
Reverse operation (1) When actual temperature is lower than set value To control heating

The initial value is "reverse operation" (to control heating).

7-18
 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.30 BFM #47 (CH1) and BFM #66 (CH2): Setting the upper limit
BFM #48 (CH1) and BFM #67 (CH2): Setting the lower limit
In BFM #47 and BFM #66, enter the upper range limit of CH1 and CH2 respectively. In BFM
#48 and BFM #67, enter the lower range limit of CH1 and CH2 respectively.
Use these BFMs to set the upper and lower limits for the temperature set value (SV) (BFM #12,
BFM #21). The default range is -100 to +1300 °C.
If the Set Value (SV) temperature is entered that is outside the input range, the "set range
error" flag (BFM #0 b1) turns ON.
If an input range value (upper/lower) is entered that is not allowable, the "set range error" flag
(BFM #0 b1) turns ON. (The same flag is used for both types of errors.)
When changing the input range values, make sure that the upper and lower limit values are
inside the allowable input range.
The allowable set range for the lower limit is the higher of two values: the default value -100 °C
or the lower limit for the sensor used (values shown on page 7-22). The allowable set range for
the upper limit is the lower of two values: the default setting of +1300 °C or the upper limit for
the sensor used (values shown on page 7-22). The initial value is the default input range (-100
to +1,300.)

7-19
 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.31 BFM #49 (CH1) and BFM #68 (CH2): Loop breaking alarm judgement time
In BFM #49, set the loop breaking alarm judgement time of CH1. In BFM #68, set the loop
breaking alarm judgement time of CH2.
The loop breaking alarm function starts to detect the variation of the measured value (PV) at
every loop breaking alarm judgment time when the output becomes more than 100% (or the
output limiter upper limit) or less than 0% (or the output limiter lower limit), then sets to ON the
loop breaking alarm (CH1: BFM #1 b8, CH2: BFM #2 b8) when judging that there is an
abnormality in the control loop.
The allowable set range is from 0 to 7,200 sec.
When BFM #49/#68 is set to "0", the loop breaking alarm function is disabled.

Abnormality judgment criteria

Table 7.5: Heating control (reverse operation)
When output is less than
When measured value (PV) does not decrease at least by loop breaking
0% or output limiter lower
change criteria (2 °C) within loop breaking set time, an alarm is issued.
limit
When output is more than
When measured value (PV) does not increase at least by loop breaking
100% or output limiter
change criteria (2 °C) within loop breaking set time, an alarm is issued.
upper limit

Table 7.6: Cooling control (normal operation)

When output is less than
When measured value (PV) does not decrease at least by loop breaking
0% or output limiter lower
change criteria (2 °C) within loop breaking set time, an alarm is issued.
limit
When output is more than
When measured value (PV) does not increase at least by loop breaking
100% or output limiter
change criteria (2 °C) within loop breaking set time, an alarm is issued.
upper limit

Abnormality targets
1) Abnormality in control target: Heater disconnection, lack of power supply, wiring mistake,
etc.
2) Abnormality in sensor: Sensor disconnection, short-circuit, etc.
3) Abnormality in operating machine: Molten relay, wiring mistake, etc.
4) Abnormality in output circuit: Molten relay inside instrument, etc.
5) Abnormality in input circuit: No change in the measured value (PV) even after input has
changed
The loop breaking alarm function judges abnormalities in the control loop, but cannot detect
positions in which abnormalities occur.
Check each part of the control system in turn.

7-20
 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.32 In BFM #50, set the loop breaking alarm dead zone of CH1.
In BFM #69, set the loop breaking alarm dead zone of CH2.
The loop breaking alarm function may issue alarms caused by disturbances (effect of another
heat source, etc.) even if there is no abnormality in the control system. In order to prevent
such alarms, by setting the loop breaking alarm dead zone, the region in which the alarm
function is disabled (non-alarm status region) can be set.
For example, if the loop breaking alarm dead zone is set to "10 °C", 10 °C above the set value
(SV) and 10°C below the set value (SV) are treated as the non-alarm status region (width of 20
°C in total).
While the measured value (PV) is located within the non-alarm region, alarm is not issued
even if the alarm condition is satisfied.
The allowable set range is form 0.0 (or 0) to the input range span (°C or °F).
When BFM #50 / #69 is set to "0", the loop breaking alarm dead zone function is disabled.

LBD operation gap *3 Non-alarm status region LBD operation gap *3

Alarm status region *1 *2 Alarm status region

Low Temperature set value (SV) LBD set value High

*1 While the temperature is rising: Alarm status region

While the temperature is decreasing: Non-alarm status region
*2 While the temperature is rising: Non-alarm status region
While the temperature is decreasing: Alarm status region 7
*3 LBD operation gap (0.01%FS)

7-21
 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.33 BFM #70 (CH1) and BFM #71 (CH2): Input type selection
In BFM #70, select the input type of CH1. In BFM #71, select the input type of CH2.
The initial value is "2".
Table 7.7:
Set Sensor Set Sensor
Input range Unit Input range Unit
value type value type
0 -200.0 to 200.0 10-1 °C 24 0 to 1800 °C
B
1 -100.0 to 400.0 10-1 °C 25 0 to 3000 °F
2 K -100 to 1300 °C 26 0 to 1300 °C
N
3 -100 to 800 °F 27 0 to 2300 °F
4 -100 to 2400 °F 28 0 to 1200 °C
PL II
5 -200.0 to 200.0 10-1 °C 29 0 to 2300 °F
6 -100.0 to 400.0 10-1 °C 30 0 to 2300 °C
WRe5-26
7 -100.0 to 800.0 10-1 °C 31 0 to 3000 °F
J
8 -100 to 1200 °C 32 -200.0 to 600.0 10-1 °C
U
9 -100 to 1600 °F 33 -300.0 to 700.0 10-1 °F
10 -100 to 2100 °F 34 0.0 to 900.0 10-1 °C
L
11 0 to 1700 °C 35 0 to 1600 °F
R
12 0 to 3200 °F 36 -50.0 to 150.0 10-1 °C
13 0 to 1700 °C 37 -200.0 to 500.0 10-1 °C
S JPt100
14 0 to 3200 °F 38 -300.0 to 300.0 10-1 °F
15 -200.0 to 200.0 10-1°C 39 -300 to 900 °F
16 E 0 to 1000 °C 40 -50.0 to 150.0 10-1 °C
17 0 to 1800 °F 41 -200.0 to 600.0 10-1 °C
Pt100
18 -200.0 to 200.0 10-1 °C 42 -300.0 to 300.0 10-1 °F
19 -200.0 to 400.0 10-1 °C 43 -300 to 1100 °F
20 0.0 to 400.0 10-1 °C
T
21 -300.0 to 400.0 10-1 °F
22 -300.0 to 700.0 10-1 °F
23 0.0 to 700.0 10-1 °F

*3 For B inputs, 0 to 399 °C (0 to 799 °F) is outside the precision compensation range.
*4 For PLII inputs, 0 to 32 °F is outside the precision compensation range.
*5 For WRe5 to WRe26 inputs, 0 to 32 °F is outside the precision compensation range.

7-22
 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.34 BFM #72 to BFM #75: Alarm mode setting

The FX2N-2LC is equipped with 14 types of alarms. Among them, up to 4 types can be used in
accordance with the application.
Write the alarm No. used in Alarm 1 to BFM #72.
Write the alarm No. used in Alarm 2 to BFM #73.
Write the alarm No. used in Alarm 3 to BFM #74.
Write the alarm No. used in Alarm 4 to BFM #75.
The alarm modes set here are applied to both channels.
However, the set value of each alarm can be set for each channel, and the alarm result can be
obtained for each channel also.
(CH1 set value: BFM #13 to BFM #16, CH2 set value: BFM #22 to BFM #25
CH1 alarm result: BFM #1 b4 to b8, CH2 alarm result: BFM #2 b4 to b8)
Or a same alarm type can be set to two or more BFM Nos.
The initial value is "0 (alarm function OFF)". For the details, refer to Section 6.
Table 7.8:
Alarm Set
Alarm type Description
No. range
0 Alarm function OFF Alarm function is disabled. ---
When measured value (PV) is more than alarm set Input
1 Upper limit input value alarm
value, an alarm is issued. range
When measured value (PV) is less than alarm set Input
2 Lower limit input value alarm
value, an alarm is issued. range
When deviation (= Measured value (PV) - Set
3 Upper limit deviation alarm value (SV)) is more than alarm set value, an alarm
±Input 7
width
is issued.
When deviation (= Measured value (PV) - Set
±Input
4 Lower limit deviation alarm value (SV)) is less than alarm set value, an alarm
width
is issued.
When absolute deviation (= ⏐Measured value (PV)
+Input
5 Upper/lower limit deviation - Set value (SV)⏐) is more than alarm set value, an
width
alarm is issued.
When absolute deviation (= ⏐Measured value (PV)
+Input
6 Range alarm - Set value (SV)⏐) is less than alarm set value, an
width
alarm is issued.
When measured value (PV) is more than alarm set
Upper limit input value alarm Input
7 value, an alarm is issued. However, when power is
with wait range
turned ON, measured value is ignored.
When measured value (PV) is less than alarm set
Lower limit input value alarm Input
8 value, an alarm is issued. However, when power is
with wait range
turned ON, measured value is ignored.
When deviation (= Measured value (PV) - Set
Upper limit deviation value value (SV)) is more than alarm set value, an alarm ±Input
9
alarm with wait is issued. However, when power is turned ON, width
measured value is ignored.
When deviation (= Measured value (PV) - Set
Lower limit deviation value value (SV)) is less than alarm set value, an alarm ±Input
10
alarm with wait is issued. However, when power is turned ON, width
measured value ignored.

7-23
FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

Table 7.8:
Alarm Set
Alarm type Description
No. range
When absolute deviation (= ⏐Measured value (PV)
Upper/lower limit deviation - Set value (SV)⏐) is more than alarm set value, an +Input
11
value alarm with wait alarm is issued. However, when power is turned width
ON, measured value is ignored.
When deviation (= Measured value (PV) - Set
value (SV)) is more than alarm set value, an alarm
Upper limit deviation value ±Input
12 is issued. However, when power is turned ON and
alarm with re-wait width
when set value is changed, measured value is
ignored.
When deviation (= Measured value (PV) - Set
value (SV)) is less than alarm set value, an alarm
Lower limit deviation value ±Input
13 is issued. However, when power is turned ON and
alarm with re-wait width
when set value is changed, measured value is
ignored.
When absolute deviation (= ⏐Measured value (PV)
- Set value (SV)⏐) is more than alarm set value, an
Upper/lower limit deviation +Input
14 alarm is issued. However, when power is turned
value alarm with re-wait width
ON and when set value is changed, measured
value is ignored.
Input range : Numeric value from the lower limit to the upper limit of input value
Input width : Width from the lower limit to the upper limit of input value (Input width = Upper
limit value - Lower limit value)
± Input width: Both a positive and negative numeric values can be set.
+ Input width: Only a positive numeric value can be set.

7-24
 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.35 BFM #76: Alarm 1/2/3/4 dead zone setting

In BFM #76, set the dead zone of alarms 1 to 4. This setting is applied to all of alarms 1 to 4.
When the measured value (PV) is near the alarm set value, the alarm status and the non-
alarm status may be repeated by fluctuation in inputs. In order to cope with such a case, by
setting the alarm dead zone, repeating of the alarm status and the non-alarm status can be
prevented.
The allowable set range is the input range (from 0.0 to 10.0%.)
Upper limit input value alarm and upper limit deviation alarm

Measured value (PV) Measured value (PV)

Alarm set value

Dead zone

Time
Non-alarm status
Alarm status Alarm status

Lower limit input value alarm and lower limit deviation alarm

7
Measured value (PV)
Measured value (PV)

Dead zone
Alarm set value

Time
Non-alarm status
Alarm status Alarm status

Upper/lower limit deviation alarm

Measured value (PV) Measured value (PV)

Alarm set
value Dead
zone
Temperature
set value (SV)
Dead
Alarm set zone
value

Time
Alarm status

Non-alarm status Alarm status

7-25
 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.36 BFM #77: Number of times of alarm 1/2/3/4 delay

In BFM #77, set the number of alarm delays. This setting is applied to all alarms 1 to 4.
The alarm delay function keeps the non-alarm status until the number of input samples
exceeds the number of alarm delays, after the deviation between the measured value (PV) and
the set value (SV) reaches the alarm set value.
If the deviation remains in the alarm range until the number of input samples exceeds the
number of alarm delays, an alarm is issued.
The allowable set range is from 0 to 255 times. (input sampling cycle: 500 ms)
Example: When the number of alarm delays, is set to 5 times

Measured value (PV) Measured value

(PV)

Alarm set value

Temperature
set value (SV)

Time
Input sampling

3 times 5 times
Alarm status

Non-alarm status
Alarm status

7.2.37 BFM #78: Number of times of heater disconnection alarm delay

In BFM #78, set the number of heater disconnection alarm delays. This setting is applied to
both CH1 and CH2.
If the abnormal status consecutively occurs in the heater current measured value (sampling
cycle: 1 sec) by the preset number of times, an alarm is issued.
The allowable set range is from 3 to 255 times.

7.2.38 BFM #79: Temperature rise completion range setting

In BFM #79, set the temperature rise completion range. This setting is applied to both CH1 and
CH2.
Set the temperature range in which the temperature rise completion range is judged based on
the temperature set value.
The actual temperature rise completion range is judged within the range above and below the
temperature set value, so the range width is twice.
Set integers from 1 to 10 for temperature (° C). (The setting value does not depend on BFM
#70 and #71 input type selection.)

Set value (SV)

Temperature rise
completion range

Temperature
rise completion

7-26
 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.39 BFM #80: Temperature rise completion soak time

In BFM #80, set the temperature rise completion soak time. This setting is applied to both CH1
and CH2.
The temperature rise completion soak time is the period of time after the measured value
reaches the temperature rise completion range until the temperature rise completion flag turns
ON.
In order to cope with a case in which the measured value has reached the temperature rise
completion range but is not stable yet, by setting the soak time, the wait time can be set for
judgement on temperature rise completion.

Example 1: When the soak time is set to "0"

Set value (SV)

Temperature rise
completion range

Temperature
rise completion

Example 2: When the soak time is set to any positive value

Set value (SV)

Temperature rise
Soak
time
Soak
time
completion range 7

Temperature
rise completion

7.2.40 BFM #81: CT monitor method changeover

In BFM #81, change over the CT monitor method. This setting is applied to both CH1 and CH2.
The current is detected by sampling performed every second.
While the temperature is controlled, the control output repeatedly turns ON and OFF.
Accordingly, the current in the ON time (= ON current) and the current in the OFF time (= OFF
current) are alternately displayed. If the output cycle is short, the displayed value is not stable
and is difficult to read.
To cope with this, the display (monitor) method can be selected.
When BFM #81 is set to "K0 (initial value)", the ON current and the OFF current are alternately
displayed.
When BFM #81 is set to "K1", only the ON current is displayed. Even in the OFF time, the ON
current remains displayed.
When control is stopped, the OFF current is displayed without regard to the setting of BFM
#81.

7.2.41 BFM #82: Set value range error address

When an out-of-range error occurs in the set value written to each BFM, BFM #82 indicates
the BFM No. in which the error occurs.
While no error occurs, BFM #82 stores "0".
When an error occurs, BFM #82 stores the BFM No. in which the error occurs. Check the set
range, set a proper value for the corresponding BFM, then reset the error (BFM #10).

7-27
 FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7

7.2.42 BFM #83: Set value backup command

BFM #83 writes the values set to BFM #12 to BFM #29 and BFM #32 to BFM #81 to the
EEPROM built in the FX2N-2LC.
When the power is turned ON, the FX2N-2LC transfers the data stored in the EEPROM to the
buffer memories and use the data as the set values for temperature control. When the set
values are backed up (written to the EEPROM) once, BFM #12 to BFM #29 and BFM #32 to
BFM #81 do not have to be set at the next time and later. As a result, as soon as control starts
(BFM #11), temperature control is enabled.
(At the time of shipment, the EEPROM stores the initial values.)

Set value backup

command

Set values are being

backed up.

Set value backup error

Description on operation
1) When the set value backup command turns on, the FX2N-2LC turns on the set value backup
flag.
2) When backup of the set values is completed, the set value backup flag turns off. When this
flag turns off, turn off the set value backup command.
3) If the set value backup command turns off while the set values are being backed up, the set
value backup error turns on. In such a case, normally back up the set values again.
If the power is turned off and on while a backup error is present, each data is reset to the
initial value.
4) While a set value range error (BFM #0 b1) is present, the set values are not backed up.

7-28
FX2N-2LC Temperature Control Block Program Example 8

1 Introduction

2 Product Configuration

3 Specifications

4 Wiring

5 Introduction of Functions

6 Alarm

7 Buffer Memory (BFM)

8 Program Example 8

9 Diagnostic
FX2N-2LC Temperature Control Block Program Example 8
FX2N-2LC Temperature Control Block Program Example 8

8. Program Example

Cautions on Startup
• Never touch any terminal while the power is supplied.
If you touch a terminal while the power is supplied, you may get electrical shock or the
unit may malfunction.
• Turn OFF the power before cleaning the unit or tightening the terminals.
If you clean the unit or tighten the terminals while the power is supplied, you may get
electrical shock.
• Thoroughly read the manual, sufficiently assure safety, then perform temperature control.
An operation mistake may cause damages in the machine or accidents.

• Never disassemble or modify the unit. Disassembly or modification may cause failure,
malfunction or fire.
* For repair, contact Mitsubishi Electric System Service.
• Turn OFF the power before connecting or disconnecting a connection cable such as
extension cable.
If you connect or disconnect a connection cable while the power is supplied, failure or
malfunction may be caused.

8-1
 FX2N-2LC Temperature Control Block Program Example 8

8.1 Program example

This paragraph introduces an example of program to operate the FX2N-2LC.
Condition
Input range : Model K -- 100.0 to 400.0 °C
PID values : Set by auto tuning
Alarm : Upper limit deviation alarm with re-wait and lower limit deviation alarm with re-
wait
Alarm dead zone : 1% (initial value)
Control response : Medium
Operation mode : Monitor + Temperature alarm + Control (initial value)
Control output cycle : 30 sec (initial value)
Normal/reverse : Reverse operation (initial value)
operation
Loop breaking : 480 sec (initial value)
alarm judgement
time
Temperature rise : 3 °C
completion range
CT monitor method : ON current/OFF current (initial value)

The control output cycle, output limiter, output change ratio limiter, loop breaking alarm
judgement time, alarm dead zone, heater disconnection alarm, sensor correction value,
adjustment sensitivity (dead zone), primary delay digital filter, setting change ratio limiter, auto
tuning bias, setting limiter and the temperature rise completion soak time are not set. (The
initial values are used.)

Device assignment
Inputs
X000: Performs initialization when the power is turned ON from OFF.
X001: Resets errors when the power is turned ON from OFF.
X002: Control start (ON)/stop (OFF)
X003: Performs auto tuning when the power is turned ON from OFF (CH1).
X004: Performs auto tuning when the power is turned ON from OFF (CH2).
X005: Writes the EEPROM when the power is turned ON from OFF.

Auxiliary relays
M0 to M15: Flags
M20 to M35: Events (CH1)
M40 to M55: Events (CH2)

8-2
FX2N-2LC Temperature Control Block Program Example 8

Data registers
D0 , D1:Set values
D2: Not used
D3: Temperature measured value (PV) of CH1
D4: Temperature measured value (PV) of CH2
D5: Control output value (MV) of CH1
D6: Control output value (MV) of CH2
D7: Heater current measured value of CH1
D8: Heater current measured value of CH2
D82: Set value range error address

8-3
FX2N-2LC Temperature Control Block Program Example 8

PLC program

M8002
MOV K1000 D0
Sets "100.0 °C" as the set value.
MOV K1000 D1
M8000
TO K0 K 12 D0 K1
Writes the set values.
While the PLC is running, the set values can be
changed using D0 and D1.
TO K0 K 21 D1 K1
M15
TO P K0 K 13 K 300 K1
Temperat Alarm 1 set value:
ure Upper limit deviation = +30.0 °C
control TO P K0 K 22 K 300 K1
ready flag

TO P K0 K 14 K-300 K1
Alarm 2 set value:
Lower limit deviation = -30.0 °C
TO P K0 K 23 K-300 K1

TO P K0 K 32 K2 K1 Operation mode:
Monitor + Temperature alarm + Control
(initial value)
TO P K0 K 51 K2 K1

TO P K0 K 36 K1 K1
Control response parameter: Medium
TO P K0 K 55 K1 K1

TO P K0 K 46 K1 K1
Normal operation/reverse operation:
Reverse operation (initial value)
TO P K0 K 65 K1 K1

TO P K0 K 47 K4000 K1

TO P K0 K 66 K4000 K1 Setting limiter upper limit:

+400.0 °C (for both channels)
Setting limiter lower limit:
TO P K0 K 48 K-1000 K1 -100.0 °C (for both channels)

TO P K0 K 67 K-1000 K1

TO P K0 K 50 K100 K1
Loop breaking alarm dead zone : ±10.0°C
TO P K0 K 69 K100 K1

8-4
FX2N-2LC Temperature Control Block Program Example 8

M15
TO P K0 K 70 K1 K1
Temperat Input type selection:
ure Type K (-100.0 to +400.0 °C) for both channels
control TO P K0 K 71 K1 K1
ready flag
Alarm mode setting:
TO P K0 K 72 K 12 K1 Upper limit deviation alarm with re-wait

Alarm mode setting:

TO P K0 K 73 K 13 K1 Lower limit deviation alarm with re-wait

TO P K0 K 79 K3 K1 Temperature rise completion range: 3 °C

CT monitor method:
TO P K0 K 81 K0 K1 ON current/OFF current (initial value)
M8000
FROM K0 K0 K4M0 K1 Flag: BFM #0 → M0 to M15

FROM K0 K1 K4M20 K1 Event (CH1): BFM #1 → M20 to M35

Event (CH2):
FROM K0 K2 K4M40 K1 BFM #2 → M40 to M55

Temperature measured value (PV):

FROM K0 K3 D3 K2 BFM #3 (CH1) → D3
BFM #4 (CH2) → D4
Control output value (MV):
FROM K0 K5 D5 K2 BFM #5 (CH1) → D5
BFM #6 (CH2) → D6
Heater current measured value:
FROM K0 K7 D7 K2 BFM #7 (CH1) → D7
BFM #8 (CH2) → D8

Set value range error address:

FROM K0 K 82 D 82 K1 BFM #82 → D82
8

8-5
FX2N-2LC Temperature Control Block Program Example 8

X000
TO P K0 K9 K0 K1
Disables Initializes all data.
initialization. When X000 is set to ON, all data is initialized.
(When initialization is not necessary, this line can
X000 be omitted.)
TO P K0 K9 K1 K1
Performs
initialization.
X001
TO P K0 K 10 K0 K1
Disables error Error reset command
reset. When X001 is set to ON, all errors indicated by
the flag (BFM #0) are reset.
X001
TO P K0 K 10 K1 K1
Performs error
reset.
X002 Starts/stops control.
TO P K0 K 11 K0 K1 When X002 turns OFF, control stops.
Stops control. When X002 turns ON, control starts.
In order to turn OFF the control output, this line
is required and cannot be omitted.
X002 (The control output cannot be set to OFF by
TO P K0 K 11 K1 K1 changeover from "RUN" to "STOP" of the PLC
Starts control. main unit.)

M15
TO P K0 K 18 K0 K1
Temperat In this example, only the auto mode is used.
ure When changeover of the mode is necessary,
control TO P K0 K 27 K0 K1 write "K1" to BFM #18 and BFM #27 in
ready flag accordance with the changeover condition.

M34
TO P K0 K 20 K0 K1
Auto tuning is Performs auto tuning.
being performed (CH1) When X003/X004 is set to ON, auto tuning is
performed.
M54 Once auto tuning has started, it continues even
TO P K0 K 29 K0 K1 if X003/X004 is set to OFF after that.
Auto tuning is When the flag (M34/M54) turns OFF while auto
being performed (CH2) tuning is performed, it is judged that auto tuning
is completed. Then, "K0" is written to BFM #20/
X003 29. By this writing, auto tuning can be
TO P K0 K 20 K1 K1 performed again.
Performs auto If auto tuning does not have to be performed
tuning (CH1). again, upper two lines can be omitted.
(M34 and M54 turn ON and off in accordance
X004 with the event status.)
TO P K0 K 29 K1 K1
Performs auto
tuning (CH2).

END

• In a practical program, if the setting has been determined by initialization or backup to the
EEPROM, it is not required to write such setting again.

8-6
FX2N-2LC Temperature Control Block Program Example 8

• In this example, the status of the flags (BFM #0) and the events (BFM #1 and BFM #2) can
be monitored using auxiliary relays (M). In order to output such status to the outside, use
each auxiliary relay as a contact and drive outputs (Y).
M0
Y0 "Error present" is output.
An error is present.

M28
Y1 "CH1 loop disconnection" alarm is output.
CH1 loop is disconnected.

M48
Y2 "CH2 loop disconnection" alarm is output.
CH2 loop is disconnected.

8-7
FX2N-2LC Temperature Control Block Program Example 8

MEMO

8-8
FX2N-2LC Temperature Control Block Troubleshooting 9

1 Introduction

2 Product Configuration

3 Specifications

4 Wiring

5 Introduction of Functions

6 Alarm

7 Buffer Memory (BFM)

8 Program Example

9 Diagnostic 9
FX2N-2LC Temperature Control Block Troubleshooting 9
FX2N-2LC Temperature Control Block Diagnostic 9

9. Diagnostic

By reading the flags (BFM #0) and the events (BFM #1 and BFM #2) using FROM instructions,
you can confirm errors (such as lack of the driving power supply 24 V, heater disconnection
and loop breaking) which can be recognized by the FX2N-2LC.
Table 9.1: Flags (BFM #0) indicating errors
Bit No. Description Operation
b0 Error present Turns ON when an error among b1 to b10 below has occurred.
b1 Set value range error Turns ON when data outside set range is written.
24 VDC power supply
b2 Turns ON when driving power supply (24 VDC) is not supplied.
error
Turns ON when an error has been caused by noise or when a
failure has occurred in FX2N-2LC.
b3 Set value backup error If contents of error are not eliminated even after power is turned
OFF once then ON again, contact Mitsubishi Electric System
Service.
·· ·· ··
· · ·
Sum check error for Turns ON when an error has been caused by noise or when a
b8
adjustment data error failure has occurred in FX2N-2LC.
Cold contact temperature If contents of error are not eliminated even after power is turned
b9
compensation data error OFF once then ON again, contact Mitsubishi Electric System
b10 A/D converted value error Service.

Events (BFM #1 and BFM #2) indicating errors

Table 9.2: Events (BFM #1 and BFM #2) indicating errors

Bit No. Assignment Description
b0 Input error (upper limit) Turns ON when input value is over scale.
b1 Input error (lower limit) Turns ON when input value is under scale.

b2
Cold contact temperature Turns ON when an error has been caused by noise or when a 9
compensation data error failure has occurred in FX2N-2LC.
If contents of error are not eliminated even after power is turned
b3 A/D converted value error OFF once then ON again, contact Mitsubishi Electric System
Service.
b4 Alarm 1 Turns ON when an alarm has occurred.
b5 Alarm 2 Turns ON when an alarm has occurred.
b6 Alarm 3 Turns ON when an alarm has occurred.
b7 Alarm 4 Turns ON when an alarm has occurred.
b8 Loop breaking alarm Turns ON when a loop breaking alarm has occurred.
Heater disconnection
b9 Turns ON when a heater disconnection alarm has occurred.
alarm
b10 Heater meltdown alarm Turns ON when a heater meltdown alarm has occurred.

When an error above has occurred, the contents described in the corresponding "Description"
column may be causes.
Eliminate causes of errors, then reset all errors using BFM #10.
If causes of an error remain, the corresponding bit turns ON again.

9-1
FX2N-2LC Temperature Control Block Diagnostic 9

Other causes of errors

In addition to the flags and the events, the following situation may be realized.
1) The FX2N-2LC does not operate with the set values written by TO instructions.
- Check whether or not the FX2N-2LC is correctly connected to the PLC.
(Check the connector positions and the connection status.)
- Check whether or not the unit No. and the BFM Nos. are correctly specified in FROM/TO
instructions.
2) The POWER LED is not lit.
- Check whether or not the FX2N-2LC is correctly connected to the PLC.
(Check the connector positions and the connection status.)
- Check whether or not the used capacity of the service power supply of the PLC main unit
exceeds the allowable range.

9-2
 USER’S MANUAL
FX2N-2LC Temperature Control Block

HEAD OFFICE: TOKYO BUILDING, 2-7-3 MARUNOUCHI, CHIYODA-KU, TOKYO 100-8310, JAPAN

MODEL FX2N-2LC-U-E
MODEL CODE 09R607

JY992D85801F Effective April 2015

(MEE) Specification are subject to change without notice.