Allen-Bradley 1756-L6 Series, Reference Manual, Page: 64 / 134

64 Rockwell Automation Publication 1756-RM001I-EN-P - May 2012
Chapter 6 FLEX I/O Modules
Wiring FLEX I/O Digital Output Modules
When using standard output modules, you must wire an output to an actuator
and then back to an input to monitor the output’s performance.
Figure 35 - FLEX I/O Standard Output Module Wiring
Write application logic so that it generates a fault in the event of a miscompare
between the requested state of an output (echo) and the actual output state
monitored by an input channel (see
Figure 34 on page 63 ).
The control, diagnostics and alarming functions must be performed in sequence.
You can also wire a standard digital output module in series with an isolated relay
output module in series with a critical actuator. In the event that a failure is
detected, the output from both output modules must be set to OFF to guarantee
the Output Loads de-energize. This is shown in
Figure 36 on page 65 .
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0
24VDC SOURCE OUTPUT
1794-OB16
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0
24VDC SINK INPUT
1794-IB16
Standard Digital Output Module
43363
Standard Digital Input Module
+24V
COM
Output
Actuator
Install a relay in position A or B. This relay is controlled by another output in the ControlLogix/FLEX I/O system. If a short circuit or fault occurs on output modules, the relay can
disconnect power to the modules. An isolated relay output module (1794-OW8) can be used for this purpose when it is connected to a different 1794-ACN15 or 1794-ACNR15
ControlNet Adapter module.
Wire output point to input
point to verify the correct
state of the output.
COM
24V DC
A
B
IMPORTANT: Other configurations are possible as long they are SIL2 approved.