Why "Aut on" system variable changed suddenly during process?

Robot Controller IRC5
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1

Hello everyone I am new here, but I have been working with ABB robots.
In this case I am working with an IRB1200 but I have a problem. Sometimes, not always, the system output variable “Aut on”, changes its value, no matter if the robot is moving or not. but does anyone have an idea why this happens?

In my PLC program when the machine is in Aut mode and everything is running I always check this variable and if I don’t have it for more than 3 seconds an error appears.
I was thinking some electrical problem, but we have checked the connections and they seem to be OK.

Maybe it is important to mention that sometimes it happens 4 times a day and other times it doesn’t happen.

If anyone has an idea it would be nice to hear back, I would appreciate it.

2

We robot programmers do not consider it to be a “variable”, it is a system output, that’s it. It could be an electrical issue depending on your communication media. If it is discrete IO, especially. Ethernet/IP or profinet, and so on, not so much. If you are using one of those busses, then it could be a matter of another signal mapped to the same output, even a group output. That will be shown in the EIO.cfg of the system parameters.