Rockwell Automation 1791DS-IBxxxx Guard I/O DeviceNet Safety Modules - Manual (Page 74)

74 Rockwell Automation Publication 1791DS-UM001J-EN-P - May 2013
Chapter 5 Configure Modules with the Logix Designer Application
Configure the
Input Configuration Tab Follow this procedure to complete the input configuration. Refer to Chapter 2
for related information.
1. From the Module Properties dialog box, click the Input Configuration tab.
2. Assign the Point Operation Type.
When you choose Equivalent or Complementary, you must also assign an
appropriate Discrepancy Time.
A discrepancy time setting of 0 ms means that the channels in a dual
configuration can be discrepant for an infinite amount of time without a
fault being declared.
For a discrepancy time setting of 0 ms, the evaluated status of the inputs
still go to the Safe State in the event of a ‘cycle inputs’ required condition,
but due to the 0 ms discrepancy time, a fault will not be declared.
A ‘cycle inputs’ required condition occurs when one input terminal goes
from its normal Active>Inactive>Active state while the other input
terminal remains in its normal Active state. Even though no fault is
declared, the inputs must be cycled before the evaluated status of the
inputs can return to the Active state.
Choose Description
Single Inputs are treated as single channels. Note that in many cases, dual-
channel safety inputs are configured as two individual single
channels. This does not affect pulse testing because it is handled on
an individual channel basis.
Equivalent
(1)
Inputs are treated as a dual-channel pair. The channels must match
within the discrepancy time or an error is generated.
Complementary
(1)
Input are treated as a dual-channel pair. They must be in opposite
states within the discrepancy time or an error is generated.
(1) Be aware that configuring discrepancy time on safety I/O modules masks input discrepancies detected by the controller
safety instructions. Status can be read by the controller to obtain this fault information.