Our application misses the PLC's brief job request. No ownership or clearing rule written down. Where do I start? This is the ordinary interface, separate from safety.
Have the PLC and application authors define the request identity, matching receipt and which side clears its own state; a pulse widened by guesswork still does not tell either side that the request was received.
Also test duplicate receipt and restart while the request is outstanding, with the saved identity retained rather than treating startup as a reason to submit another inspection.