Who owns clearing the job handshake? (Fairino FR5, sample verification)

JoBaker0505 · 12 Aug 2026, 22:44 UTC

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JO
JoBaker0505
I'm reviewing our non-safety job handshake for sample verification with Fairino FR5 in a workshop inspection station awaiting commissioning, using a fixture-mounted bracket. 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.

10 replies

AA
AaronBennett0697
Replying to JoBaker0505

Does your trace show when the PLC request is raised and cleared relative to application polls, including which side performs the clearing?

6 points
JO
JoBaker0505
Replying to AaronBennett0697

@AaronBennett0697 I've compared the trace: the PLC raises and clears the request between consecutive application polls, with no observed acknowledgement before it clears.

11 points
AA
AaronBennett0697
Replying to JoBaker0505

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.

18 points
HA
HanaCarter0970
Replying to AaronBennett0697

@AaronBennett0697 Settle it? Retaining a request fixes visibility, but can also keep an old request alive after a restart. Identity and reset rules matter.

-1 points
AA
AaronBennett0697
Replying to HanaCarter0970

@HanaCarter0970 Yes, I overstated that. Retention addresses the missed pulse. The offline review also needs matching identity, reset ownership and restart cases before the design is complete.

14 points
JO
JoBaker0505
Replying to AaronBennett0697

@AaronBennett0697 Would your table include who reads each field too? Our notes say used by PLC, which could mean practically anything.

8 points
AA
AaronBennett0697
Replying to JoBaker0505

@JoBaker0505 Include the writer and readers alongside the field's meaning and the conditions for setting and clearing it, with examples showing the permitted transitions.

19 points
AN
AnikaArcher0421
Replying to AaronBennett0697

My setup had two programs clearing the acknowledgement under different conditions. Reviewing them together exposed a conflict that wasn't apparent from either program in isolation.

0 points
JO
JoBaker0505
Replying to AnikaArcher0421

@AnikaArcher0421 The missed pulse is explained, and I've got an ownership review to work from. Our complete handshake behaviour is still open.

14 points
AA
AaronBennett0697
Replying to JoBaker0505

That's a useful partial result: the missed request is explained, while ownership and transitions remain unsettled.

9 points

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