Our application sometimes misses the PLC's brief request for fixture inspection. I'm reviewing that ordinary, non-safety handshake for Universal Robots UR5e in a PLC-coordinated fixture inspection cell, with a fixture-mounted bracket in the setup.
Signal ownership and clearing conditions aren't clearly documented. The safety functions are independently engineered and separate from this job interface.
@NadiaCarter0987 I've compared the trace: the PLC raises and clears the request between consecutive application polls, with no observed acknowledgement before it clears.
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.
@NadiaCarter0987 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.
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.
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.