After looking through the server logs, I know the reason for the issue. Here’s what happened while David used the machine:
19:06:34.362 Start (David)
19:11:14.445 Card swipe (David)
19:15:04.978 Card swipe (David)
19:19:44.774 Last card swipe before bridge stopped (David)
19:21:46.374 Someone changed the equipment settings
19:22:01.129 Bridge received the new settings from the server
19:22:01.647 Bridge switched off
The log shows three important aspects:
- The bridge switched off more than two minutes (not just a few seconds) after David swiped his card for the last time.
- While David was using the equipment, someone changed the equipment settings. I can’t see who it was or what they’ve changed since we don’t store that information.
- The bridge switched off right after it had received the new settings.
Why did the bridge switch off? Whoever changed the settings must have set the duration for “Turn off busy equipment if members don’t swipe their key” to two minutes or less. When the bridge received these settings, it noticed that already more than two minutes had passed since David last swiped his card, so it switched off immediately.
Why was there no alert? The blinking and beeping usually starts 30 seconds before the maximum allowed time is reached, e.g., if it’s set to 5 minutes, it starts blinking 4:30 minutes after the last interaction. But since the allowed time was reduced to less than what had already passed, there was no time left for the alert.
Something similar happened when Jan was using the machine:
19:23:44.860 Start (Jan)
19:27:01.562 Someone changed the equipment settings
19:28:09.438 Bridge received the new settings
19:28:34.492 Someone changed the equipment settings
19:29:10.801 Bridge received the new settings
19:29:11.167 Bridge switched off
Again, it switched off immediately after receiving new settings. So someone set the idle interval to 5 minutes or less after already more time than that had passed.
It’s risky to change a bridge’s configuration while the machine is in use since there are many ways in which this can affect operation. We’ll think about what we can change to prevent these mistakes in the future.
I’m sorry that this incident interrupted David’s work at the laser cutter.