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

@JamieBaker0469 Take an ownership table and a retained-request proposal to the interface owner. A request held until matching acknowledgement should settle the handshake in an offline review.

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

@ReeceBarnes0558 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.

@HassanBarnes0530 Would your table include who reads each field too? Our notes say used by PLC, which could mean practically anything.

@JamieBaker0469 Yes: writer, readers, meaning, set condition and clear condition. Then give each legal transition a concrete example.

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

@GraceBell0668 i've checked our assignments and found that too: both sides can clear acknowledgement. i'll put both conditions in the review rather than quietly choose one.

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

i haven't established reliable request and acknowledgement behaviour for our interface. Finding the missed transient doesn't complete that design.

@JamieBaker0469 Understood. One explained transient doesn't amount to a verified request-and-acknowledgement design.