Rockwell Automation 1794 FLEX I/O System with ControlLogix for SIL2 - Manual (Page 28)

Publication 1794-RM001G-EN-P - December 2011
3-6 FLEX I/O Modules
Users 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 3.6.
Figure 3.6 ControlLogix/FLEX I/O Standard Output Module Wiring With an Isolated
Relay Module
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 SOURCE OUTPUT 1794-OB16
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0
24VDC SOURCE OUTPUT 1794-OB16
Isolated Relay
Output Module
43364
Standard Digital
Input Module Standard Digital
Output Module
+24V COM Wire output point
to input point to
verify the correct
state of the output
Output
Output Actuator
+24V
COM
Note 1: An external relay can be replaced with an isolated
relay module which is mounted in another FLEX I/O rail.