Who owns clearing the job handshake? (sample verification)

ChenArcher0355 · 2026年4月15日 23:16 UTC

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CH
ChenArcher0355
I'm reviewing our non-safety job handshake for sample verification with Fairino FR5 in a PLC-coordinated fixture inspection cell, 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.

19 条回复

GA
GabrielAli0192

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

4分
CH
ChenArcher0355

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

-1分
GA
GabrielAli0192

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.

11分
AN
AnilBaker0462

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

7分
GA
GabrielAli0192

@AnilBaker0462 You're right; my conclusion skipped necessary cases. Retaining the request addresses visibility, while identity, clearing ownership and restart behaviour must also be reviewed.

4分
CH
ChenArcher0355

@GabrielAli0192 Should I record readers as well as the single writer? Our existing phrase used by PLC doesn't distinguish setting, reading or clearing a field.

8分
GA
GabrielAli0192

@ChenArcher0355 Yes: writer, readers, meaning, set condition and clear condition. Then give each legal transition a concrete example.

17分
LI
LiamChan1099

On my interface, both sides cleared acknowledgement for different reasons. Each program looked reasonable alone. Put them together and the answer vanished.

18分
CH
ChenArcher0355

Our code also lets both sides clear the acknowledgement. I've identified the competing conditions and will bring them to the interface review for an explicit decision.

4分
AN
AnilBaker0462

Good. Renaming the field won't remove the second writer. The agreed ownership needs to match both programs

23分
NO
NoraArcher0409

@GabrielAli0192 Does the acknowledgement indicate that inspection is complete, or might it only mean the request was accepted?

1分
GA
GabrielAli0192

That depends on the defined interface. If it means accepted, completion needs a separate event. Don't make readers infer which meaning you intended.

10分
CH
ChenArcher0355

@GabrielAli0192 I'll distinguish request acceptance from job completion in our review, so an accepted request with a delayed result can't appear completed just because it was acknowledged.

5分
LI
LiamChan1099

@ChenArcher0355 A step-by-step example from idle to acceptance and completion, showing each field's value, can reveal missing transitions in the proposed interface.

21分
NO
NoraArcher0409

@LiamChan1099 Should the offline review also follow a request that receives no acknowledgement, rather than only the successful sequence?

8分
GA
GabrielAli0192

Include missing acknowledgement and the documented recovery ownership. A timeout doesn't by itself justify submitting the work again, so that transition needs explicit treatment.

12分
CH
ChenArcher0355

Our offline review will include a retained request without acknowledgement, keeping it distinct from the transient request the application never observed.

5分
CH
ChenArcher0355

The missed-request diagnosis is settled for this trace. Completing the handshake fix still depends on the interface owner's assessment of signal ownership and the offline transition cases.

13分
GA
GabrielAli0192

You've closed the specific missed-pulse question without assuming that explains or verifies every handshake transition.

8分

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