Rockwell Automation 1791ES-IB16 Guard I/O EtherNet/IP Safety Modules - Manual (Page 24)

24 Rockwell Automation Publication 1791ES-UM001D-EN-P - May 2013
Chapter 2 Understand the Operation of Safety Functions
Figure 8 - Equivalent, Normal Operation and Fault Detection (not to scale)
Dual-channels, Complementary
In Complementary mode, the inputs of a pair must typically be in the opposite
(complementary) state. When a transition occurs in one channel of the pair prior
to the transition of the second channel of the pair, a discrepancy occurs. If the
second channel transitions to the appropriate state prior to the discrepancy time
elapsing, the inputs are considered complementary.
If the second transition does not occur before the discrepancy time elapses, the
channels will fault. The fault state of complementary inputs is the even numbered
input turned off and the odd numbered input turned on. Note that if faulted,
ON
OFF
IN0
Safety Input 0
IN1
Fault Detected
Discrepancy Time
Remote
I/O
Data
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
IN0
Safety Input
Status 0, 1
IN1
Fault Detection
Remote
I/O
Data
ON
OFF
ON
OFF
ON
OFF
Discrepancy Time
Safety Input
Status 0, 1
Safety Input 1
Safety Input 1
Safety Input 0
Normal Operation