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  1. #1
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    fanuc 18m 351 alarm

    I have a Supermax v65A with a fanuc 18MC controller.
    It used to produce a 351 x-axis alarm followed by a 414 alarm in X-axis. (most of the times, into a toolchange cycle).
    After a little investigation I found that the previous owner tried to replace the X encoder cable. Eventually, he didn't replace the whole cable but only half of it.
    I believed that was the problem together with some kind of cable-grounding error.
    I have replaced the cable by myself, but I still see from time to time a 351 x axis alarm, even when the machine is on and stoped (controller into MDI mode ).

    Any suggestions?

    Thanks
    Michael

  2. #2
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    Re: fanuc 18m 351 alarm

    I swapped axis cables and error disappears.
    Any thoughts?

  3. #3
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    Re: fanuc 18m 351 alarm

    Is it possible to have the problem due to a broken spark killer or diode, because most of the times, the alarm is happening during M06 cycle?
    Has anyone met anything similar?

    Thanks
    Michael

  4. #4
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    Re: fanuc 18m 351 alarm

    try to put some ferite core on your encoder cables if you do not have,might be some noise on your wires.

  5. #5
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    Re: fanuc 18m 351 alarm

    I have tried ferrites but nothing changes.
    The fact that after I do a cable swap between X and Y axis and still the error is 351 x-axis alarm and not 351 y-axis alarm,I think it is not the servo drive.
    I have already tried a new encoder with no luck.
    Is this any possibility of a faulty CPU?

    Michael

  6. #6
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    Re: fanuc 18m 351 alarm

    you should have 2 axis card control on the mainboard,1 is for 1,2 axis and one is for 3,4 axis.
    Swap them and see if the alarm goes to Z or 4th axis.

  7. #7
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    Re: fanuc 18m 351 alarm

    I have a 3 axis card.Which cables should I swap? Cables to motor, encoder and control cables?

  8. #8
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    Re: fanuc 18m 351 alarm

    i was not talking about the driver that powers the motors,i was talking about the servo module cards from the main board,you should have 2 identical and u can swap them,just identify it and try.
    If you do not know and is hard for you to take out the mainboard just call Fanuc.

  9. #9
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    Re: fanuc 18m 351 alarm

    I swap servo module a20b-2902-00700 of 1/2 axis with the same module of 3/4 axis.Problem still the same and most of the cases when in or after a while of a toolchange cycle?
    The manual suggests when #5(STB) and #6(CRC) is 1 then
    a) signal cable is disconnected
    b) serial pulse coder is faulty
    3) main cpu board is faulty (i don't have option board 2)

    Maybe I must change the main CPU board or any module of it?

  10. #10
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    Re: fanuc 18m 351 alarm

    When the tool change is executed ,the X and Y go to reference points?

  11. #11
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    Re: fanuc 18m 351 alarm

    No, just where the program is interrupted, X and Y stop at whatever point they are,M06 is executed and then the program continues (if the error doesn't happen)
    The error would be happen anytime inside the m06 cycle, or just a few seconds after m06 ends.
    If I will run a program having m06 always with the same tool (avoiding toolchange) the error will happen again but some time later, let's say from 2mins to 15mins later.

  12. #12
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    Re: fanuc 18m 351 alarm

    did u have the machine grounded?i mean a solid wire from the main body to the centerline of factory ground?
    do you have equipment that is welding using same power line as the machine does?

  13. #13
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    Re: fanuc 18m 351 alarm

    The machine is grounded.
    Everithing is happening when no other equipment is on at the factory.
    The strange thing is that 90% of the circumstances, the alarm is happening during or afterwards a toolchange.
    I though it might be a spark killer of the motor that brings the umbrella of the tools forward and backward to the spindle, or this motor's brake.
    I dont know how to check the spark killer and the brake is supplied ok with 90v when the umbrella motor is moving.

    Another thing is that our mains is 410V but the transformer of the machine is 380V. I have already ordered a new tranformer so I would check with 220V and not 234V as is now.
    The transformer is a little noisy, at the back side of the machine, and close by is the metal pipe whitch has the x-pulse coder cable inside. I moved the transformer about 0.5m away but still no luck.
    The power cables go from the transformer to the machine and back and for some length we have 2 power cables near the metal pipe which has the x-pulse coder inside and the metal pipe which has the y-pulse coder inside.
    I have checked DC bus is at the upper limit of DC.
    24v is OK
    5V is ok

    Thanks
    Michael

  14. #14
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    Re: fanuc 18m 351 alarm

    ok let me understand the atc cycle:
    -magazine rotate to the tool number in spindle;
    -z goes up to reference point
    -umbrella has a pneumatic cylinder moving foward to spindle side
    -tool unclamp
    -z moves to second ZRN to go out from tool
    -magazine rotates to desire tool;
    -z moves down to the tool
    -tool clamp
    -umbrella moves backward
    tool change complete

    if this is happening on tool change i would try to isolate what moving from this tool cycle is generate the alarm
    you should have M codes for magazine foward/backward;
    if so,make a small program with some dwell time between and do some magazine moving foward and backwards for ,lets say 30 minute and see if it is happening.
    also u can also do on the rotation ogf magazine by making a program with only calling a tool in standby with no tool change,like:
    T1;
    G04 X15.
    T2;
    G04 X15.
    ....

    In this way you will isolate the umbrella and motor moving.

    good luck and let us know about results.

  15. #15
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    Re: fanuc 18m 351 alarm

    The toolchange is happening exactly as you mention exept it has not a pneumatic cylinder but a 3phase motor.

    When the alarm is generated during the toolchange macro, it doesn't happen on a specific instance. Maybe it will happen when magazine goes forward to spindle side, maybe when it goes backward, maybe when z leaves the old tool, maybe when z goes down to clamp the new tool.
    It is possible to do 3 toolchanges in a row from MDI without an alarm but it will happen on the next.
    The alarm never happens when the magazine rotates buring the toolchange macro.

    I have tried to move the magazine, calling the M codes for back and forth as you said but I couldn't succeed.

    Do you think the mainboard is ok? and we have not as a cause to the alarm some noise?
    Maybe I should change the pulse coder and its cable again?

  16. #16
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    Re: fanuc 18m 351 alarm

    yes,the pulsecoder of X should be identical to Y axis so can be changed,also the cable from motor to cabinet side.

    PS:for me sounds like the there is a cable issue for the encoder of X

  17. #17
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    The alarm is happening always with the x axis stopped. I have tried to move the cable from both ends in case any of its wires is loose although I checked its wiring and ground.

  18. #18
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    Re: fanuc 18m 351 alarm

    I have started from the begining to find maybe a pattern of what happens to trigger the alarm.
    This morning I referenced the machine then issued a M19 spindel orientation into MDI mode and all the times after some seconds the alarm happened without any movement of the machine.
    If a just reference the machine without doing anything then alarm doen't appear.

  19. #19
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    Re: fanuc 18m 351 alarm

    so if you try M19 several times will generate the alarm?

  20. #20
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    Re: fanuc 18m 351 alarm

    Every time, but the time the alarm follows it varies from 2 sec to 10 sec.
    I found that my machine has a M sensor and a position coder because there are cables connected to JY2 and JY4 ports of the spindle amplifier.
    My spindle motor is A06B-0854-B100 and the amplifier is A06B-6078-H211

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