I'm reviewing our non-safety job handshake for sample verification with Fairino FR5 in a sample-checking cell with separate safety controls, using an inspection coupon. The PLC sends a brief request, and our application sometimes misses it. I can't find anything clear about who owns each signal or when it gets cleared.
Safety functions are independently engineered; this is the ordinary job interface.
Our application keeps missing a brief PLC request (Fairino FR5, sample verification)
AlexBrown0907 · 4 Jun 2026, 01:08 UTC
4 replies
Replying to AlexBrown0907
Does your trace show when the PLC request is raised and cleared relative to application polls, including which side performs the clearing?
14pointsReplying to AaronBennett0697
Our trace shows it rising and falling between two polls. The PLC clears it without an observed acknowledgement. No wonder the application misses it.
12pointsReplying to AlexBrown0907
Draft one writer and clear conditions for each field, then review a request retained until matching acknowledgement with the interface owner. That should settle the handshake offline.
22pointsReplying to AaronBennett0697
Holding the request addresses the missed pulse, but it doesn't settle the interface. A retained request needs identity and restart rules to avoid being mistaken for new work.
-1pointsAdd to the discussion
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