Rockwell Automation Publication 1734-UM013N-EN-P - September 2017 29
Safety Inputs, Safety Outputs and Safety Data Chapter 2
Dual-channel Mode and Discrepancy Time
To support dual-channel safety devices, the consistency between signals on two
channels can be evaluated. Either equivalent or complementary can be selected.
If the length of a discrepancy between the channels exceeds the configured
discrepancy time (0…65,530 ms in increments of 10 ms), the safety input data
and the individual-safety input status turn off for both channels. In Dual-channel
Complimentary mode, the safety input data goes to off/on for input channels
n/n+1 respectively as described in Ta b l e 3
.
This table shows the relation between input terminal states and controller input
data and status.
The dual-channel function is used with two consecutive inputs that are paired
together, starting at an even input number, such as inputs 0 and 1, 2 and 3.
If you are using the safety application instructions with a GuardLogix®
controller, set the inputs of the module inputs to Single (default). Do not use
the dual-channel mode of the module, as this functionality is provided by the
safety application instructions.
Table 3 - Terminal Input Status and Controller I/O Data
Dual-channel Mode Input Terminal Controller Input Data and Status Dual-channel
Resultant
Data
Dual-channel
Resultant
IN0 IN1 Safety
Input 0 Data
Safety
Input 1 Data
Safety
Input 0 Status
Safety
Input 1 Status
Dual-channels, Equivalent OFF OFF OFF OFF ON ON OFF Normal
OFF ON OFF OFF OFF OFF OFF Fault
ON OFF OFF OFF OFF OFF OFF Fault
ON ON ON ON ON ON ON Normal
Dual-channels, Complementary OFF OFF OFF ON OFF OFF OFF Fault
OFF ON OFF ON ON ON OFF Normal
ON OFF ON OFF ON ON ON Normal
ON ON OFF ON OFF OFF OFF Fault
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