Robot drops out of auto with no alarm present

I have a robot with an 30ib plus controller that keeps dropping out of auto for no apparent reason. Has been running for 3 years. When it happens while in cycle it looks like it is doing a controlled stops. No red lights or anything so. I trended immediate stop, hold and enable in the PLC, they all do not drop out (it is not on a safety PLC though, I can't rule out some wiring issue)

Earlier today it stopped almost every cycle. After a cold start the issue seemed to have disappeared, but now is back intermittently.

I already talked to Fanuc, they blame the PLC or a communication issue. I hooked up a new ethernet cable and a different port on the switch, no change. I also swapped the teach pendant from different robot.

Would be really appreciative for any suggestions. I am just scratching my head at this point.

Quote from gpunkt

Did you check the alarm history?
Is the program paused (halted) or aborted?

Only way I can think of that will pause the program without a trace would be if someone pushed the HOLD button on the TP.

When this happens, make an All Of Above backup, then check the LOGBOOK.LS file to see if you can spot when/where/why it's happening. Would also be a good idea to make sure that the clock of the robot controller is correctly set in order to better be able to use the LOGBOOK.LS

I did check the alarm history. I also checked the logbook (btw you can go to the webpage of the robot and view under "Active Program Variables / Diagnostics" / "Error/Diagnostic files (text) available on MD"). Nothing.

The program is halted, not aborted.

Quote from Martinezr8173

Do you perhaps have an IRvison connected to the robot?

There is a 2d irvision on the robot, the analog one, not gigE. It is not being used though.