Fanuc OM pulse coder parameter
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  1. #1
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    Default Fanuc OM pulse coder parameter

    hi i change servo motor on the X axis and i have problem

    on the machine shows on the desktop 1 mm shoe on the sensor 0.8mm
    old damaged servo motor was 3000 pulse encoder but new one have 2500 on the pulse coder and here is problem with this (on the descop 1mm travel on the sensor 0,8mm)
    which parameter pulse encoder i have to change to solve this problem ?
    please help
    FANUC O-M control machine 3 axis VMC

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    Easiest fix would be to put the encoder from the old motor onto the new motor unless the encoder was the original problem. If that was the case though, why change the motor instead of just getting the correct new encoder.

    I'll look at my 0 series information later today. Since there is a relationship between the pitch of the screws and encoder counts for a given machine resolution, some combinations can not be accommodated by parameter unless your version of 0 control supports the "flexible feed gear" function.

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    thank you for reply
    ok please check

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    Do you know what version of 0M control you have? Also what are the values set in parameters...

    4?
    35?
    100?
    8123?
    8124?

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    check tommorow parameter and let you know,how check version?
    Last edited by wojtekthx; 06-17-2019 at 04:28 PM. Reason: add words

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    Quote Originally Posted by wojtekthx View Post
    ....how check version?
    When you power up the control there will be a 4 digit number that will flash on the screen. For the 0 series control it should be 04xx-xx.

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    software 0460-03
    PMC;4001-01
    parameter 4
    01111001
    parameter 35
    00000000
    parameter 100
    2
    parameter 8123/8124
    10000

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    Based on those parameters the 2500 PPR encoder should be correct. Are you sure that the original encoder was not 2500PPR and the replacement is 3000PPR. 3000PPR encoder is most often used on a 4th axis or machines with 12mm pitch ballscrew.

    Also, what values are in parameters 8184 and 8185?

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    parameter 8184/8185 is 0

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    Since those are 0 then your machine is not using flexible feed gear function.

    I'm still puzzled by your description of the what you have for the other parameters I asked about and the encoders you say you are trying. The parameter settings you posted previously are what I would expect for a machine with 2500PPR encoders and a 10mm pitch screw. They would also work with a 3000PPR encoder and a 12mm pitch screw with the exception of parameters 8123 and 8124 being 10000 which is for a 2500PPR encoder instead of 12000 which would be the setting for a 3000PPR encoder.

    Also in the first post you note that the machine does not travel as far as the commanded move. This is the behavior of a higher count encoder used in place of a lower count encoder.

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    Vancbiker, not to derail from this guy's problem, but what software/control versions can use flexible feed gear? I'd like to know if you do, just for future reference (although I do not want to have to use the knowledge!)

    We replaced a ballscrew on a 0m machine (I think it is a 0mc or f), I do not believe it had flexible feed gear (or if it did, i did not know how to get it to work at the time.) Original screw was 10mm, the MTB sent us a 12mm screw as a replacement, and we didn't realize it until it was installed.

    I tried parameters and such but we ended up just buying a new pulse coder and putting it on the old motor, and adjusted parameters accordingly

    I know you mentioned it to him in an earlier post in this thread, but I'd be inclined to just suggest he replace that. Whether that is a swap with the old motor's PC or buying one on ebay (they are maybe 100$ or so on ebay iirc back then?). If he only replaced the motor and not the ballscrew, he probably won't have to reconfigure the half dozen or so parameters related to it.

    He may have the numbers mixed up in his first post about which was 2500 and 3000.

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    Quote Originally Posted by dandrummerman21 View Post
    Vancbiker, not to derail from this guy's problem, but what software/control versions can use flexible feed gear? I'd like to know if you do, just for future reference.......
    My oldest 0 series documents are for the C version. The flexible feed gear function was available on those with software 0466-20 or later and if the machine builder selected digital servos.

    Having the flexible feed gear function allows use of encoder count and screw pitch combinations that would not work when only specific values for CMR and DMR parameters were available. It really became helpful when retrofitting a rotary axis to a machine. Some of those got real weird when taking a belt ratio and a worm gear ration into account when trying to establish 360,000 resolution and an encoder that did not have a count divisible by the ratios.

    Yeah, the OP has not been real forthcoming with information for us to try to help him out.

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    Thank you. Apparently it might have been possible on that machine, software version 0469-08 and it has digital servos.

    I still have a warmer fuzzier feeling knowing the pulse count divides into the pitch of the screw. Although after changing it, I had a pretty good pucker factor when doing the first tapping job there (it was the z screw I replaced). I didn't want to break the 15/16 tap in the big hunk of aluminum...

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    Quote Originally Posted by dandrummerman21 View Post
    Thank you. Apparently it might have been possible on that machine, software version 0469-08 and it has digital servos.

    I still have a warmer fuzzier feeling knowing the pulse count divides into the pitch of the screw. Although after changing it, I had a pretty good pucker factor when doing the first tapping job there (it was the z screw I replaced). I didn't want to break the 15/16 tap in the big hunk of aluminum...
    Yes, you could have done it on that machine. It's a standard function too, no option parameter needed to use it.

    It is easiest just to use the correct replacement encoder. When you start changing parameters like those you have to careful to back up the new settings and get rid of old backup files and hard copies. I have done quite a few service calls to sort out why things don't work like they used to after someone restored data from a backup that was not up to date.


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