Discrepancy time monitoring

The safety option carries out discrepancy time monitoring for input pairs in the two-channel equivalent and two-channel non-equivalent connection types. The discrepancy time monitoring verifies whether the two input signals are delivering error-free levels that match the switching state of the sensor. A deviation is tolerated for the parameterized discrepancy time. An input error occurs if the deviation from the expected signal state exceeds the discrepancy time.

The safety option carries out a switch test function for the input pair in the two-channel equivalent and two-channel non-equivalent connection types in order to check the connected switch for correct switching behavior following a detected discrepancy error. The switch test function can be activated and deactivated for the input pair via a parameter. The switch test function assumes that the switch contacts are moved into the opened/activated state after the occurrence of the discrepancy error so that the two input signals assume the required state for the switch test:

• Connection type two-channel equivalent
• F-DI00_A = logical "0"
• F-DI00_B = logical "0"

• Connection type two-channel non-equivalent
• F-DI00_A = logical "0"
• F-DI00_B = logical "1"

Only in this case can the discrepancy error be acknowledged; acknowledgment is otherwise impossible and the input remains in the discrepancy error.