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Thread: Fanuc OMA 446 axis disconnection alarm

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    Default Fanuc OMA 446 axis disconnection alarm

    Hello,
    I am interfacing a fourth axis onto an old leadwell MCVO. Just about have everything sorted except this 446 (4th axis) disconnection alarm. It is caused when the NC does not receive feedback from the encoder. I have swapped everything from the Z axis and vice versa to fault find and the issue stays with the 4th axis so im confident its not cable or drive related. I have also swapped the CMD and FB cables that connect between the NC and the axis servo drives. My guess is it could be the add i/o card I had to install for the extra axis or the main board. The alarm only comes up when I change the 907 parameter that enables the 4th axis. The drive has no alarms visible. Could anyone suggest some diagnostic parameters to check or any other ideas?

    Many Thanks

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    Default Re: Fanuc OMA 446 axis disconnection alarm

    O controls had LSI chips on them for each axis on them . Do you have all 4?

    Sent from my SM-T813 using Tapatalk



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    Default Re: Fanuc OMA 446 axis disconnection alarm

    Quote Originally Posted by underthetire View Post
    O controls had LSI chips on them for each axis on them . Do you have all 4?
    Thanks for the reply, can you please let me know what an LSI chip is?



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    Default Re: Fanuc OMA 446 axis disconnection alarm

    FS0A uses additional PCB A16B-1210-0590 for 4th axis



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    Default Re: Fanuc OMA 446 axis disconnection alarm

    Yes I have installed a A16B-1210-0590 card for the 4th axis with A06B-6050-H103 servo and A06B-0513-B001 motor. I have connected it to the Z axis servo and jogged the rotary table so I know the wiring to the motor and encoder is fine. I have swapped the encoder cables between Z and 4th axis also and the alarm does not transfer to the Z axis. What I am unsure of is if there is a parameter to address the 4th axis servo to the new axis card or should the NC use it by default now its installed?

    Thanks again



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    Default Re: Fanuc OMA 446 axis disconnection alarm

    IC similar to that on the picture is the LSI
    is it installed on the PCB?
    Fanuc OMA 446 axis disconnection alarm-s-l1000-jpg



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    Default Re: Fanuc OMA 446 axis disconnection alarm

    Yep it looks like it has 4 of them

    Fanuc OMA 446 axis disconnection alarm-main-board-large-jpg



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    Default Re: Fanuc OMA 446 axis disconnection alarm

    one of those 4 LSI is spindle
    you should have one LSI on additional card I/O A3
    and BTW why don't you increase RAM?



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    Default Re: Fanuc OMA 446 axis disconnection alarm

    Yes there is one of those chips on the Add I/O card. Don't know much about the ram, will that just increase storage or is it like ram in a PC



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    Default Re: Fanuc OMA 446 axis disconnection alarm

    upload parameters
    you can add RAM chips and change parameters, but keep in mind that in this matter you will lose all data such as parameters, programs, offsets
    so you should have backup



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    Default Re: Fanuc OMA 446 axis disconnection alarm

    Quote Originally Posted by guhl View Post
    upload parameters
    you can add RAM chips and change parameters, but keep in mind that in this matter you will lose all data such as parameters, programs, offsets
    so you should have backup
    Hi Guhl,
    I'm just wondering what advantage it is to add the additional RAM?



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    Default Re: Fanuc OMA 446 axis disconnection alarm

    more space for programs
    of course DNC or network solves the problem with memory space, but you have to got it



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    Default Re: Fanuc OMA 446 axis disconnection alarm

    Thanks for the info. Due to the limited storage, max 48Kb for OMA I tend to drip feed most programs.



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    Default Re: Fanuc OMA 446 axis disconnection alarm

    try "PMC axis control" option



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    Default Re: Fanuc OMA 446 axis disconnection alarm

    I tried enabling parameter 910.5 "axis control by PMC" but no change. The parameter wouldn't even update with PWE 1. It's proving to be a tricky one. Do you know of any diagnostic parameters I can check?

    Thanks again for the suggestions.



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    Default Re: Fanuc OMA 446 axis disconnection alarm

    do you have 4th axis name on the display?
    is I/O card installed into I/O slot?

    Attached Thumbnails Attached Thumbnails Fanuc OMA 446 axis disconnection alarm-i_o-pcb-pdf  


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    Default Re: Fanuc OMA 446 axis disconnection alarm

    Thanks Guhl,
    Yes once I change parameter 907.3 the A axis is displayed on the screen and the 446 alarm comes up. I definitely have the I/O card in the I/O slot as per the drawing. There is no card in the PMC slot but the machine did come with one in a box of spares A16B-1210-0810 PMC-M. Parameter 905 is set to "PMC Model L" so that must just use the ladder on the master board with the IC's in the PMC-L slots?

    Thanks for that attachment, it's excellent. ,Would you have any other technical documentation you would be willing to share that is OMA specifc?

    Last edited by Rxv; 07-30-2017 at 06:34 PM.


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    Default Re: Fanuc OMA 446 axis disconnection alarm

    yes, CNC operates with ladder from PMC-L chips
    do you have listing of it?
    what is software version number (legend on ROM chips)



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    Default Re: Fanuc OMA 446 axis disconnection alarm

    I have a paper copy of the ladder in my manual. All the logic for the 4th axis appears to be there. Not sure about the software version - does MBM2764-25 mean anything?

    Fanuc OMA 446 axis disconnection alarm-pmc-l-jpg



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    Default Re: Fanuc OMA 446 axis disconnection alarm

    I meant another ROM chips
    I've led round them
    What ladder copy do you have - from PMC-L or from additional PCB with PMC-M?
    Fanuc OMA 446 axis disconnection alarm-main-board-large-jpg



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