Programmable Logic

Controllers

PLC I/O Module Types and PLC

Trainer Configuration

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-1

Basic Module Types

• Digital (discrete) output modules
– Optical isolation provided
– Relay, transistor or triac based
– Transistor-based outputs may be
• Current sourcing or
• Current sinking
• Digital (discrete) input modules
– Optical isolation provided
– Diode based
• Current sinking, sourcing or both depending on device

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-2

11-1
Relay Output Module

OUT6
7
6
CPU Actuator

0 common
Power
+/- -/+

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-3

Relay Output Module

• Coil actuated switch closing
• AC or DC switching
– Relay determines current carrying capacity
• More expensive relay I/O modules may have
two external contacts per relay
– Separate actuator and power supply can be
connected to each relay-controlled circuit
– Most flexible in terms of power types (AC or DC)
and connections
• Less expensive relay I/O module
– Common contact for a group (or all) outputs

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-4

11-2
Current Sourcing Transistor
Output Module

OUT6
Current 
7
6
C
CPU Actuator
B

E
0
Power
+ -
Positive
common

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-5

Current Sinking Transistor

Output Module

OUT6
 Current
7
6
C
CPU Actuator
B

E
0
Power
- +
Negative
common

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-6

11-3
Transistor Output Modules
• PNP transistors used in current sourcing
output modules
• Positive common may be shared across all
(or groups of) inputs
• NPN transistors used in current sinking
output modules
• Negative common may be shared across all
(or groups of) inputs
• BE AWARE OF THE OUTPUT TYPE
– Sourcing vs. Sinking
• Power supply connections are different between the types

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-7

Current Sourcing/Sinking TRIAC

Output Module

OUT6
7
6
CPU Actuator

0
Power
+/- -/+
common

TRIAC allows current flow in either direction if triac’s gate contact

is energized. Power supply polarity is not important. AC is allowed.
More expensive than transistor-based modules.

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-8

11-4
Current Sinking Optoisolated
Input Module

+5V IN6
7  Current
6
CPU sensor

0
Power
- +
common

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-9

Current Sourcing Optoisolated

Input Module

+5V
7 IN6
6 Current 
CPU sensor

0
Power
+ -
common

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-10

11-5
Sinking/Sourcing Optoisolated
Input Module

+5V
7
6 IN6
CPU
sensor

0
Power
+/- -/+
common

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-11

Micrologix 1100 controller

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-12

11-6
Controller Wiring
• 1763-L16BWA
– 120V AC input power
– (6) 24 Vdc inputs
– (4) high-speed 24 Vdc inputs
– (6) relay outputs
– (2) voltage inputs 0-10Vdc (Not used on the trainer)

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-13

Trainer Wiring
(sink/source input module)

• All inputs (I/0-I/9)have similar wiring.

• I/0-I/2 have a normally open momentary pushbutton
• I/3-I/5 have a normally closed momentary
pushbutton
• I/6-I/9 have toggle switches attached to the input

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-14

11-7
Trainer Wiring
(relay output module)
24Vdc
- power supply +

AC power All outputs have similar wiring.

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-15

MicroLogix™ Analog Input/Output

Module (1762-IF2OF2)
• 1a upper panel mounting tab
• 1b lower panel mounting tab
• 2 power diagnostic LED
• 3 module door with terminal
identification label
• 4 bus connector with male pins
• 5 bus connector cover
• 6 flat ribbon cable with bus
connector (female)
• 7 terminal block
• 8 DIN rail latch
• 9 pull loop
• 10 input type selector switch

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-16

11-8
Input Type Selection
• Select the input type, current or voltage, using the switch located on the modules
circuit board and the input type/range selection bits in the Configuration Data
File.
• You can access the switch through the ventilation slots on the top of the module.
– Switch 1 controls channel 0;
– switch 2 controls channel 1.
• The factory default setting for both switch 1 and switch 2 is Current. Switch
positions are shown below.

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-17

Output Type Selection

• The output type selection, current or voltage, is made by
wiring to the appropriate terminals, Iout or Vout, and by the
type/range selection bits in the Configuration Data File.

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-18

11-9
Input Data File

• For each module, slot x, words 0 and 1 contain the analog

values of the inputs.
• The module can be configured to use either raw/proportional
data or scaled-for-PID data.

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-19

Status Bits
• SIx = General status bits for input channels 0 and 1.
• SOx = General status bits for output channels 0 and 1. This
bit is set when an error (over- or under-range) exists for that
channel, or there is a general module hardware error.
• OIx = Over-range flag bits for input channels 0 and 1.
• OOx = Over-range flag bits for output channels 0 and 1.
These bits can be used in the control program for error
detection.
• UIx = Under-range flag bits for input channels 0 and 1.
• UOx = Under-range flag bits for output channels 0 and 1.
These bits can be used in the control program for error
detection.

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-20

11-10
Output Data File

Electrical & Computer Engineering Dr. D. J. Jackson Lecture 11-21

11-11