Repeating a routine.
We have a problem with our dual cell set up. We are running a 1400 and 6400 series for a welding and stacking process. The problem is the 1400 is repeating the routine that is called for some reason. The process is: The bots are started and they both run the routine for the product being made/welded. They are both welding on the same part till the end of the routine, the 6400 will go into a gripper routine to grab the the product and stack it, (only if the 1400 has completed its routine and has given the signal that it is done), then the 6400 will go into it's stacking routine, then it goes back to the main routine. The problem is happening at the end of the 1400's routine, it is not going to the main routine, it is staying in the same routine and repeats it, and the 6400 has the signal to pick up the product up while the 1400 is repeating the routine and it ends up in a big mess.
The 1400 is randomly doing this, and it only repeats it once. I checked the I/O's and there is nothing telling it to start again, I have searched the program for errors and found nothing.
For the bots to get the signal to start there has to be several I/O's made first.
I loaded a different prg. and haven't seen this problem since then. my question is what would cause it to repeat a routine on its own.