Discrepancy time monitoring

The safety option performs 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 fault-free levels that match the switching state of the sensor. A deviation is tolerated for the parameterized discrepancy time. An input fault occurs if the deviation from the expected signal state exceeds the discrepancy time. The discrepancy time can be adjusted for each input pair via a parameter.

The safety option executes a switch test function for input pairs in the "two‑channel, equivalent" and "two‑channel, non-equivalent" connection types to verify the correct switching behavior of the connected switch after a discrepancy fault is detected. The switch test function can be activated and deactivated for each 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 fault so that the two input signals assume the required state for the switch test:

• "Two‑channel, equivalent" connection type
• F-DI. = logical "0"
• F-DI. + 1 = logical "0"

• "Two‑channel, non-equivalent" connection type
• F-DI. = logical "0"
• F-DI. + 1 = logical "1"

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