Hello,

We are running a fairly basic machine tending program. The main program consists of several If statements which call out subroutines.

Within the subroutines there are also If statements which direct robot which rack to pick build plates from. Within the If statements we are setting a flag so as not to enter this particular If statement again (rack is now empty). When program scan gets to bottom of If statements within subroutines, controller just randomly dies. This would be right before program would be expected to jump back to main program. There are no error logs. It only states that "prog stopped running" and "controller disconnected".

Any ideas?

@Jason_g,

Can you share that program or the sequence that you think is faulty?

I have seen that problem before when the user wrongly used the comparison equal sign (?=) versus the assignment equal sign (=). I don't remember the particular case though.

Nickolas,

Attached is subprogram. Please not "monitoring expression continuously" is unchecked. 

Program
   Robot Program
     MoveJ
       pMidway
     If Nest1_Full<1  and  Rack1>0  and HoldingNest≟ False
       MoveJ
         pApproachNest1
         rq_move_and_wait(150)
         MoveL
           pDwnNest1
           rq_close_and_wait()
           CheckHoldNest≔ True
           Wait: 0.2
           CheckHoldNest≔ False
           Wait HoldingNest≟ True
           pUpNest1
           pUpNest1Ret
           pApproachNest1
           pMidway
           Rack1≔0
           Wait: 0.2
     If Nest2_Full<1  and Rack2>0  and HoldingNest≟ False
       MoveJ
         pApproachNest2
         rq_move_and_wait(150)
         MoveL
           pDwnNest2
           rq_close_and_wait()
           CheckHoldNest≔ True
           Wait: 0.2
           CheckHoldNest≔ False
           Wait HoldingNest≟ True
           pUpNest2
           pUpNest2Ret
           pApproachNest2
           Rack2≟0
           Wait: 0.2
     If Nest3_Full<1 and Rack3>0  and HoldingNest≟ False
       MoveJ
         pApproachNest3
         rq_move_and_wait(150)
         MoveL
           pDownNest3
           rq_close_and_wait()
           CheckHoldNest≔ True
           Wait: 0.2
           CheckHoldNest≔ False
           Wait HoldingNest≟ True
           pUpnest3
           pUpNest3Ret
           pApproachNest3
           Wait: 0.2
     sync()

I can't find any potential errors in there. Have you tried removing all subprograms and putting them back in the main one?

@Jason_g is the CheckHoldNest flag triggering a thread or event to fire?  If so, can you post that code?  Also, does the controller disconnect at the same point in the program each time?  What version of Polyscope are you running?

We see this issue when the system encounters a fault that it doesn't know how to handle so its possible but i agree that it shouldn't as its a valid comparison.  If you put it back in what happens?

@Jason_g

It is possible that this is in fact causing the problem. Have you tried putting it back as matthewd92 mentioned? What is happenning?

I'm not exactly sure why you're using a thread to validate the gripper position? Why wouldn't you simply call a subprogram? You could also consider using the Grip Check node included in the latest Gripper URCap 1.2.1.

This is exactly the problem I previously saw then. You should consider sending that to UR as this is an easily made mistake.

@Jason_g, I didn't think you were triggering the thread from a subroutine. But you're right, it is not possible to call a subprogram from a subprogram.