KRC2 stability issues, random operating mode mismatch

  • Hello everyone,

    few months ago I restarted using my robot: KR210-2 2000 from 2008

    with cabinet KRC2 edition2005, from BMW, KSS 5.5.16 and SafeRobot 1.1

    Suddently, since last week, without touching anything it gives randomly:


    404 EMERGENCY STOP safety controller

    484 Operating Mode mismatch with input T1 on SafeRDC


    Since those errors are not listed in the manual,

    someone has a guess on the cause?

    On the pendant it appears a question mark on the operating mode icon.

    -?-

    I already tried to replace the pendant,

    also tried reinserting all the safety bridges and contacts on X11 and X40, with no luck,

    same thing for all the connectors on the ESC CI3 board;

    it works for 10 / 15 minutes, than it trips, and I have to reboot it removing the power,

    (or power cycling the ESC board and acknowledge the errors,

    disconnecting and reconnecting X6 on, or the external X11).

    That means ESC A - B chain has an error, correct?


    I have some hints, I'm suspicious (or they are only coincidences)

    that it happens most of the times near the switching on or off of the cabinet fan (it is very hot these days),

    or near the switching on or off of the drives contactor.


    Also to note, sometimes it trips a 300mA RCD in the middle of an operation

    (not only at the switch on or off, i know that it is common)

    Can it be because there is a slightly higher line voltage than usual?


    Sometimes (way less frequently) it gives

    common KSD-Error A2

    Maybe is it related to a power bus fault from KPS-600?


    There is also a problem with the KPC control pc:

    while doing a lot of tests to diagnose,

    in two occasions it was not booting,

    and i had to reseat all the cards inside it.


    In conclusion, I disconnected and reconnected about everything inside the cabinet,

    the error keeps popping up...

    any help or guesses would be appreciated.

    Thank you

    Edited once, last by crk ().

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  • next time it happens, take good picture of the diagnostics screens and bit-fields. send them to KUKA, they have table to decode them and tell you what is wrong.

    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

  • The operating mismatch is gone,

    but sadly, it keeps tripping the RCD in the middle of automatic operations,

    (2 times since yesterday)

    and it gives:


    common KSD-Error A2

    motor cable A2


    I swapped A2 and A3 KSDs, but the problem is still on A2,

    can it be the motor that leaks to ground?

    Can be that a cause to fail for the KPD-600?

  • it is possible that motor or motor cable are bad. defects could appear intermittently too which makes troubleshooting harder. and such failure would stress/propagate to upstream component (KSD, KPS/RCD).


    also any time A2 is mentioned, one should check if counterbalance is ok and if it is a correct type for current installation.

    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 checked all the cables, even the ones that run inside the robot arm,

    they look pretty good.

    Shouldn't it say "torque exceeded" or something like "torque error" in case of faulty counterbalance?

    The error appears almost everytime at the same position (A1 90°)

  • I checked all the cables, even the ones that run inside the robot arm,

    they look pretty good.

    Doesn't mean they are good. Conductors can begin to fail inside jackets that look fine. Also, the motor connectors (any of the cylindrical connectors KUKA uses, really) are vulnerable to having their pins pushed back into the housing and making only partial contact. And it's often not obvious, unless you use a pair of needle-nose pliers on each pin and gently push/pull on them to see if they're seated firmly or "float".

    This can also happen on the motor, instead of the cable.

    Shouldn't it say "torque exceeded" or something like "torque error" in case of faulty counterbalance?

    Probably, yes. But as Panic says, any A2 problem is a reason to at least do a quick check of the counterbalance for any obvious issues.

    The error appears almost everytime at the same position (A1 90°)

    Ah! Now that suggests an issue with one of the cables running from the bas socket up through the center of the A1 casting. My bet would be that the cable is getting marginal, and something about A1 being at 90deg is disrupting the conductors by putting stress on the cable at just the right angle.

  • Thank you, indeed i checked the cables that run inside the base,

    no bad bending, no scratching, good grease,

    also checked all the pins at the various connectors and enclosures,

    and the error didn't appear again since saturday.

    Let me hope that it was only some dust/oxidation,

    it is a pain to replace the A2 power cable with all those crimped pins.

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