Drives have been discharged

  • Everyone,


    I am currently working with several KRC4 robots (KR120 3500 Ultra). I currently have a robot that has given the following message.


    "Drives have been discharged: Reason Drives_Off"


    usually I just cycle power and the message goes away. However this message begun to impede production and I worry that this could error could become a error that can not be fixed by cycle power.


    My question is, what does this message mean? How are the drives becoming discharged? and how do i fix it.


    ANY ADVICE IS WELCOME


    -Jbodell

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  • robot is using rectifier to convert 3phase AC into DC which then powers bus and servo drives.
    drives discharged means that DC bus is low. this can happen for many reasons (safety circuit tripped, requested by PLC if using EXT mode, machine data mismatch, etc.). you need to focus on other messages.

    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

  • When does this message occur? Does it actually halt the robot? Does it only occur if the robot has been held unmoving for some length of time?


    "Drives_OFF" almost suggests to me that the $DRIVES_OFF signal from the PLC was lost, for some reason.

  • SkyeFire,


    This message has appeared randomly during run time. However this message appears most of the time when the robot cycles power. This prevents me from even jogging the robot until I recycle the power. there has been a few time(twice) that i needed to restore a image backup in order to get the robot up and running.


    the thing that makes me think its not the PLC is that we have 7 other machines just like it that are running fine.


    -Jbodell

  • are you using EXT mode? if so what is connection to PLC (fieldbus or physical I/O)? what does the safety circuit look like? how many robots you have there (can you swap hardware between cabinets)?

    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

  • they were just not conditioned... enough. :icon_wink:
    wait till this becomes bigger problem than it is right now... :pfeif:


    anyway, what I would do is start by checking if DRIVES_OFF goes low and why.
    could be PLC program, wiring of I/O between robot and plc, etc.

    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

  • I also have this sort of problems on few robots now, JonHopper do you maby rmemeber how did you solve this issue ?
    External mode works like charm, but every few weeks we have this same error and we have to restart drives.
    Kuka hotline didn't help us much, they blame PLC, but when I check signals on robot I can see they all are OK like every other time.


    Robot: KR420R3330
    KR C4 V8.3.30

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