Occasional resume from start when resuming program from M0

We're using the powerbrick with firmware 2.4.0.180. We frequently have M0 in our programs and resume from the M0 using the NC UI Cycle Start. I've seen a few instances lately where seemingly at random, the program restarts from the beginning instead of where it left off. Running the same program again does not necessarily show the problem again. Can anyone offer any suggestions as to why this would happen?

What are you doing while the system is paused?

 

One thing that comes to mind is that typically, one form of the command to start a motion program is something along the lines of "& b r". If the "b " or even just the character "b" were issued while the system were paused, that would reset the program counter to the beginning of the motion program. That said, I'm not sure if the normal method to resume execution would be enough to start the program running again.

Thanks. All that should be happening is the usual NC UI variable polling. I suppose it's possible that somehow if one of the getters/setters is incorrect, a "b" gets in there and messes things up. Is there a way to access the program counter to monitor when it's getting reset?

I see another thing that could be happening is that ProgActive is getting set to 0, which would cause the CycleStart command to restart the program even if the program counter is in the right place. Is there anything that could cause ProgActive to be set to 0 aside from an abort or disable command?

I think I've determined that the problem is user error, users were doing something that was resetting the program. Thanks for the help.