Robot starts the next movement after reset skipping the first position

  • Hello all,


    As a part of our pick and place solution using KUKA and PLC Software, I am facing some problems when I reset the program from KUKA SamrtPad. The situation is:


    When the robot is at one position and stays there because of the error in PLC program, so I first reset the program from SmartPad and drives the Robot to home position. But when I again Start the program after some correction in PLC Program Software, Robot skips the first position and starts from the next movement after the point where I have reset the program.


    When I reset the program from SmartPad, the robot should starts from the new position and not the previous one. Is it not like that?


    I appreciate any help in this.

  • It depends on how the programs are structured. It is common to keep the data of already transferred products so that one can abort and continue job. To actually start from scratch, one would need to physically remove pallet that is partially populated, place new (empty) pallet, reset data and THEN the program can start from scratch...

    1) read pinned topic: READ FIRST...

    2) if you have an issue with robot, post question in the correct forum section... do NOT contact me directly

    3) read 1 and 2

  • It depends on how the programs are structured. It is common to keep the data of already transferred products so that one can abort and continue job. To actually start from scratch, one would need to physically remove pallet that is partially populated, place new (empty) pallet, reset data and THEN the program can start from scratch...

    But when I reset PROGRAm pallet is not on hand and I assumed that when I reset the program from SmartPad, robot positions are also reset (and should be current HOME position). Is my assumption wrong here?

  • your assumption is wrong. first because you assumed (never do that) and also because system obviously does not do what you expected.


    one can write palletizing/depalletizing code using FOR loops etc as is common in training such (as KUKA Programming2) or examples shared here on the robot forum. reality is that those are starting point examples. in such case loop counters would be reset as soon as program is reset or restarted.


    but reality is that in practice things are a bit different....


    if restarting program meant that not just starting point in code was reset but also variables got reset, then your cell would need a lot of manual labor every time program is stopped for whatever reason.


    normally you do not want to reset or re-initialize things like loop variables even if program is restarted because:

    a) you don't want to replace pallet so robot can restart

    b) you don't want to manually complete the job (this is why we have a robot, let it do palletizing)

    c) failure to ensure correct start scenario when program is restarted will result in a crash.

    etc.


    so you really want to make sure that the initialization only takes place when new pallet is brought in, not every time program is reset or restarted or robot is rebooted. this way you can run partial load/unload of the pallet, then somewhere halfway through the sequence you can (intentionally or not, maybe there is a power outage) power everything down and go home for a weekend...

    next time when you are back, just need to power up and press start. robot knows what is still on the pallet and can continue.


    if you have a single robot, you may say it's not big deal. some floor worker will be given task of completing the job and making sure things are restarted in correct conditions. but if you have 500 cells and power goes out suddenly. your restart could take days instead of minutes.

    1) read pinned topic: READ FIRST...

    2) if you have an issue with robot, post question in the correct forum section... do NOT contact me directly

    3) read 1 and 2

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