RobotStudio event

RS loses write access to VC (error 20051)


I have a RS station which I have been using for a long time without any issues. The recent problem may have appeared after upgrading to RS 6.08. Right after opening the station the VC works normally. After running the session for some time the problem appears. It's related to actions which require write access to VC. For example 'Apply', 'Check Program' and  'Set PP to Routine' fail and raise the error described below:

20051: Not allowed command

The command is only allowed when the client is in control of the resource (program/motion).

The system remains in the same status, and the requested action will not be performed.

1) Check if the client is in control, by checking "Write Access" in RobotStudio.

2) Check if the client who ought to be in control really is.

This is confusing since RS is supposed to manage write access automatically. Therefore Request and Release Write Access buttons are grayed out. Controller status is 1/1 (green). I have not found any way to recover from this other than closing the station and RS. Extremely annoying since the recent program changes are lost.

Any thoughts?

Best regards,




  • VC is running RW 5.15.13


  • DenisFR
    DenisFR ✭✭✭
    edited December 2018
    Just got the same just after saving station.
    RW 5.61.8001.08

    Have to restart RS completely.
    Restarting VC (only able by FlexPendant) doesn't fix it.
    Post edited by DenisFR on
  • It seems like this behaviour is connected to Virtual FP. I stopped using it and used Operator Window instead. No 20051 errors since then. 
  • I got the same problem on 2022.2.1 version of RS. I couldn't modify my value in the RAPID code.

    I don't know if it is the correct behavior (I am still new) when we are on auto mode but I unblocked it when I passed on manual mode.