Wiring flex i/o digital input modules, Figure 3.2, Figure 3.3 – Rockwell Automation 1794 FLEX I/O System with ControlLogix for SIL2 User Manual
Page 25
Publication 1794-RM001G-EN-P - December 2011
FLEX I/O Modules 3-3
Wiring FLEX I/O Digital
Input Modules
The wiring diagrams in Figure 3.1 show two methods of wiring the digital
input Module. In either case, users must determine whether the use of 1 or 2
sensors is appropriate to fulfill SIL2 requirements.
Figure 3.1 ControlLogix Digital Input Module Wiring
Application logic can compare input values or states for concurrence.
Figure 3.2
The user program must also contain rungs to annunciate a fault in the event of
a sustained miscompare between two points.
Figure 3.3
Input 1
Input 2
Input
COM
+24V
1 2
3 4 5
6 7
8 9 10 11 12 13 14 15
0
24VDC SINK INPUT
1794-IB16
1 2
3 4 5
6 7
8 9 10 11 12 13 14 15
0
24VDC SINK INPUT
1794-IB16
1 2
3 4 5
6 7
8 9 10 11 12 13 14 15
0
24VDC SINK INPUT
1794-IB16
1 2
3 4 5
6 7
8 9 10 11 12 13 14 15
0
24VDC SINK INPUT
1794-IB16
Input
COM
+24V
Input 1
Input 2
SIL2 SENSOR
SENSOR
SENSOR
+24V dc
Optional relay contact
to switch line voltage
for periodic automated
testing
43366
One-Sensor Wiring Example
Two-Sensor Wiring Example
43366
Note 1: Both sensors are monitoring the same safety application.
1
1
Input B
Input A
Actuator
Input B
Input A
Input B
Input A
Timer
Timer preset in milliseconds to
compensate for filter time and
hardware delay differences.
Fault
Timer Done
Alarm to Operator
Fault