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  1. #1

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    Oct 2019
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    Computer Noise??

    I have an Industrial CNC machine with Mach3 controls through a UC-100 USB adapter. I run through Dell laptop (16 Gb Ram, i7 processor). I am having issues with tripping limit switches and the machine going off the intended program profile. The manufacturer told me to disconnect the limit switches from the CNC driver processor, which I have done. This has eliminated the limit switch tripping but I still see to have an issue with the CNC machine getting out of synch with the program causing at least 1/16" shift in in the x,y, and z directions. The manufacturer is telling me the problem is due to interference noise in the computer or environmental. Has anyone had this problem?
    Thanks,
    Kevin

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  2. #2
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    Re: Computer Noise??

    Quote Originally Posted by K_Schulz View Post
    I have an Industrial CNC machine with Mach3 controls through a UC-100 USB adapter. I run through Dell laptop (16 Gb Ram, i7 processor). I am having issues with tripping limit switches and the machine going off the intended program profile. The manufacturer told me to disconnect the limit switches from the CNC driver processor, which I have done. This has eliminated the limit switch tripping but I still see to have an issue with the CNC machine getting out of synch with the program causing at least 1/16" shift in in the x,y, and z directions. The manufacturer is telling me the problem is due to interference noise in the computer or environmental. Has anyone had this problem?
    Thanks,
    Kevin

    Sent from my moto g(6) using Tapatalk
    This is a common problem when a machine has not been wired correctly Poor Grounding no EMI Power Filter installed Etc what machine do you have you should never have to remove the limit switches to fix this problem
    Mactec54

  3. #3

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    Re: Computer Noise??

    Quote Originally Posted by mactec54 View Post
    This is a common problem when a machine has not been wired correctly Poor Grounding no EMI Power Filter installed Etc what machine do you have you should never have to remove the limit switches to fix this problem
    Ok, thanks for the response. I didn't want to remove the limit switches but it seemed worth a try. I would like to get this machine operating correctly. After I check over the connections that I did and any other obvious connections; what would be the next step? I requested an electrical schematic but what I got was a diagram that showed what should be connected (no V or A).

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  4. #4
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    Re: Computer Noise??

    Quote Originally Posted by K_Schulz View Post
    Ok, thanks for the response. I didn't want to remove the limit switches but it seemed worth a try. I would like to get this machine operating correctly. After I check over the connections that I did and any other obvious connections; what would be the next step? I requested an electrical schematic but what I got was a diagram that showed what should be connected (no V or A).

    Sent from my moto g(6) using Tapatalk
    What machine do you have and supply Voltage ???

    Does it have a VFD Drive ???
    Mactec54

  5. #5

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    Re: Computer Noise??

    The manufacturer is Industrial CNC, 4x8 with 220V supplied. There is a VFD. I will send pictures later today.

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  6. #6

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    Re: Computer Noise??

    Here are a couple pictures

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  7. #7
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    Re: Computer Noise??

    Quote Originally Posted by K_Schulz View Post
    Here are a couple pictures

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    That USB cable needs to be double shielded and with ferrite cores, how long is this cable, you want these cables to be as short as possible, this will most likely what is getting hit the most, if you install a EMI Power Filter wired close to the VFD Drive a lot of the problems will go away, but your USB cable will need the Ferrites at each end also
    Mactec54

  8. #8

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    Re: Computer Noise??

    Quote Originally Posted by mactec54 View Post
    That USB cable needs to be double shielded and with ferrite cores, how long is this cable, you want these cables to be as short as possible, this will most likely what is getting hit the most, if you install a EMI Power Filter wired close to the VFD Drive a lot of the problems will go away, but your USB cable will need the Ferrites at each end also
    The cable is about 3'. It is the cable that came with the UC100 unit.

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  9. #9
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    Re: Computer Noise??

    Quote Originally Posted by K_Schulz View Post
    The cable is about 3'. It is the cable that came with the UC100 unit.

    Sent from my moto g(6) using Tapatalk
    Which in most cases is no good as it is, add some ferrite cores at each end this will help a little, but you first have to add a EMI Power Filter by the VFD Drive as well

    You could also put a shield around the UC100 that has a completely exposed CPU inside where it is mounted even your light fixtures can upset a sensitive device like this
    Mactec54

  10. #10

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    Re: Computer Noise??

    There are several types of EMI filters to select from. What would be the requirements and does this get installed outside the enclosure or inside? I will install the snap-on ferrite pieces on each side of the USB cable. Are you suggesting to enclose the uc-100 device in ferrite?
    Kevin Schulz

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  11. #11

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    Re: Computer Noise??

    Thanks for you help the ferrite chokes and EMI Powe filter seems to be helping. I appreciate you taking the time for my problem.

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  12. #12
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    Re: Computer Noise??

    Quote Originally Posted by K_Schulz View Post
    Thanks for you help the ferrite chokes and EMI Powe filter seems to be helping. I appreciate you taking the time for my problem.

    Sent from my moto g(6) using Tapatalk
    The EMI Power Filter needs to be close to the VFD Drives input power to have the most affect this would be inside the enclosure to help the UC100 just a aluminum shield would help which if attached to the cabinet would be Grounded for a test you could use aluminum foil
    Mactec54

  13. #13

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    Re: Computer Noise??

    I did install the EMI filter on the power input to the vfd. I also install ferrite chokes on the wire from the computer to the uc100, the other input and output at vfd, and power wiring. I did put a couple ferrite rings around the uc100 unit. Seems to help but I still cannot connect my limit switches cable without getting a tripped limit switch error and the error will not reset on Mach3.


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  14. #14
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    Re: Computer Noise??

    Quote Originally Posted by K_Schulz View Post
    I did install the EMI filter on the power input to the vfd. I also install ferrite chokes on the wire from the computer to the uc100, the other input and output at vfd, and power wiring. I did put a couple ferrite rings around the uc100 unit. Seems to help but I still cannot connect my limit switches cable without getting a tripped limit switch error and the error will not reset on Mach3.


    Sent from my moto g(6) using Tapatalk
    Go into Mach3 and adjust the Debounce this is in the General Logic Configuration this will help with the limit switches, this is just a Band-Aid fix if it works, you need to find the source of the noise, you must have some bad Grounding or lack of Shielded cables some were, is the output cable of the VFD U V W a Shielded Cable if not then this will have to be changed to a Shielded cable so you would want a 4 wire shielded cable the Ground must be connected at the spindle and the VFD Drive the Shield must be connected also at Both Ends as the below snips show
    Mactec54

  15. #15
    Community Moderator Al_The_Man's Avatar
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    Re: Computer Noise??

    Personally I would fit a 3phase choke/filter on the output side of the VFD first, I have found the radiation/noise is far more prevalent on the output due to switching noise.
    The input is pretty well suppressed via the very large bridge and capacitor bank.
    Also bond all cabinet grounds, bring them together at one point.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  16. #16

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    Re: Computer Noise??

    Some pictures of the system. I don't think the wiring is shielded.

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  17. #17
    Community Moderator Al_The_Man's Avatar
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    Re: Computer Noise??

    The VFD motor wiring does not even look twisted together !
    Three radiators!
    Particularly if travelling with low voltage conductors.
    Max
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  18. #18

    Re: Computer Noise??

    The VFD doesn't have an input filter either. You should always fit the recommended RFI filter on the ac input. Without that, there will be horrendous high frequency noise flying around the whole ac circuit. Combined with the VFD output wiring being mingled in the cable guides, you'd have to be surprised if it DIDN'T misbehave.

    So often, people build systems and then try to fix issues, rather than follow recommended practice which avoids the problems in the first place. I expect you will find the user / installation manual will provide recommendations for an input filter and output wiring. The exception might be your Chinesium VFDs, even if you could make sense of the machine translated text.

  19. #19
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    Re: Computer Noise??

    Quote Originally Posted by K_Schulz View Post
    Some pictures of the system. I don't think the wiring is shielded.[IMG]https://uploads.tapatalk-cdn.com/20200717/ad3e4929454c27376d1de551cf2b9511.jpg

    Sent from my moto g(6) using Tapatalk
    By the look of the VFD Drive wiring that is really bad, and where all your EMI is coming from, what I can see it does not even have the needed Ground wire so this part of it should be rewired from the spindle to the VFD Drive you need a 4 core cable with a shield

    What size is your spindle motor, then I can spec a cable for you, that will fix this mess
    Mactec54

  20. #20
    Community Moderator Al_The_Man's Avatar
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    Re: Computer Noise??

    Quote Originally Posted by Muzzer View Post
    The VFD doesn't have an input filter either. You should always fit the recommended RFI filter on the ac input. Without that, there will be horrendous high frequency noise flying around the whole ac circuit. Combined with the VFD output wiring being mingled in the cable guides, you'd have to be surprised if it DIDN'T misbehave.

    .
    In has been my experience that there is far more EMI coming from the output of the VFD rather than the input, especially as in this case where the correct wiring is deficient in many areas.
    I have consistently used a 3ph inductor on the motor side with satisfactory result.
    When a standard induction motor is used, it is beneficial for the motor as well as the drive.
    Reference:
    Various VFD manufacturers.
    Al.
    .
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

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