Edge evaluation of F‑DI process data

Observe the following points for edge evaluation of F-DI process data in the higher-level controller for safety-relevant functions:

• Only the 0 → 1 edge may be used. The 1 → 0 edge must not be used as it can occur at any time during the transition to the safe state, e.g. in the event of a detected fault or a line interruption.
• The higher-level controller may only evaluate the edge if the process data bit changes from 0 to 1 and the "Qualifier process data" is set to "OK" (logical 1) for both the value "0" of the process data bit and the value "1" of the process data bit. If it is set to "Fault" (logical 0), the edge must be ignored.
• It is ensured that all edges evaluated in the higher-level controller were actually present at the F‑DI input terminal.
• What cannot be ensured is that all edges occurring at the F‑DI input terminal are detected by the higher-level controller. This must be particularly observed in the event of a defect in the safety option or the cabling.