Which acknowledgement belongs to my retry? - fixture inspection

HanaBrown0883 · 24 Apr 2026, 03:45 UTC

Closed
HA
HanaBrown0883
I'm reconstructing a failed fixture inspection attempt on Universal Robots UR5e in a commissioning station recording job events, using a machined bracket. Our Python log, PLC trace and controller event list have disagreeing timestamps. The application also reused its job label after a restart. I can see a timeout, but I can't tell which attempt an acknowledgement belongs to

11 replies

DI
DineshBennett0734
Replying to HanaBrown0883

@HanaBrown0883 Got a process-start entry? That could separate the reused labels without trusting another machine's clock.

15points
HA
HanaBrown0883
Replying to DineshBennett0734

@DineshBennett0734 Found it. I can split our Python log into two sessions. Still no attempt match for that PLC acknowledgement, though

10points
DI
DineshBennett0734
Replying to HanaBrown0883

Keep source order, label the sessions and leave that acknowledgement unassigned. Comparing the timestamps alongside them should establish the combined order.

18points
RI
RickShift
Replying to DineshBennett0734

Those clocks disagree. No offset or causal link, no established combined order.

0points
DI
DineshBennett0734
Replying to RickShift

You're right; i went too far. Timestamps suggest matches. Keep source order and mark cross-system links uncertain unless evidence supports them.

20points
HA
HanaBrown0883
Replying to DineshBennett0734

I'll keep that acknowledgement unassigned. One tidy sequence would look nicer, but choosing the nearest request by timestamp would be a guess

4points
RO
RobinBennett0773
Replying to HanaBrown0883

My merged log fooled us after a machine clock adjustment. Keeping the original source order let us untangle our confidently wrong interpretation.

10points
FA
FarahBrooks0852
Replying to RobinBennett0773

Would monotonic time fix it? Or only inside one process?

10points
DI
DineshBennett0734
Replying to FarahBrooks0852

@FarahBrooks0852 Inside a running process. Machines and restarts don't automatically share that clock, so keep a session ID and wall-clock reference too.

19points
HA
HanaBrown0883
Replying to DineshBennett0734

This resolves how I'll present the incident: separate source sequences, application sessions identified, and the unmatched acknowledgement left uncertain. I'm not claiming that establishes the job's final outcome

8points
DI
DineshBennett0734
Replying to HanaBrown0883

That gives readers an honest incident view without making the unknown result look settled.

12points

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