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  1. #1
    Join Date
    Mar 2017
    Posts
    8

    Need help installing limit switches

    I am trying to wire up my limit switches, but I'm having issues with linking the limit switch to my software. I am running supercamxp and I am using 3 plug limit switches. I have my limit switch hooked up to the right pin and the com port is Hooked up to the ground. This is the first time I have done something like this so it may be something dumb, but any help would be greatly appreciated.


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  2. #2
    Join Date
    Jun 2005
    Posts
    1723

    Re: Need help installing limit switches

    You hook up limit switches by using the COM connector pin and the NC connector pin. Look at the limit switches closely and you should see these labels which stand for Normally Open, Normally Close, and Common.

    The common pin connects to ground and the other end goes to the port input pin. If you are using the limit switches as home switches as well they all hook to a different input pin. If these are only for limits you chain all of the limits together in serial fashion for X,Y,Z, X-,Y-,Z-, so if any limit is hit is shuts down the machine since something must be wrong.

    Russ

  3. #3
    Join Date
    Mar 2017
    Posts
    8

    Re: Need help installing limit switches

    Could I possibly hook the normally closed up to power and then the com port up to the input pin because for some reason the software isn't getting a signal.


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  4. #4
    Join Date
    Jun 2005
    Posts
    1723

    Re: Need help installing limit switches

    What is most likely wrong is you have the cnc software port configuration set wrong. The input pins for limit switchs should be set to active LOW, it is probably set to active HIGH. Most parallel ports pull the inputs high with resistors. You also need to check your Break OutBoard as some of those invert that logic. What kind of BOB are you using?

    Russ

  5. #5
    Join Date
    Mar 2017
    Posts
    8

    Re: Need help installing limit switches




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  6. #6
    Join Date
    Mar 2017
    Posts
    8

    Re: Need help installing limit switches

    This is the bob or driver does the switch have to be hooked up to the drivers


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  7. #7
    Join Date
    Jun 2005
    Posts
    1723

    Re: Need help installing limit switches

    That is a stepper motor driver. The BOBis the little board that connects to the parallel port. Some outputs from the BOB connect to the step and direction input on the stepper driver board. The limit switches connect to the BOB normally not the driver.

    Russ

  8. #8
    Join Date
    Mar 2017
    Posts
    8

    Re: Need help installing limit switches


    This is the bob.


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  9. #9
    Join Date
    Jun 2005
    Posts
    1723

    Re: Need help installing limit switches

    By the way the step and directioninputs on your motor driver requires differential inputs. You can covert single ended outputs from a parallel port by using a differential driver converter. Cnc4pc sells them for about $8for each axis. Look on their website. If you don't have aBOB they sell those as well

    Russ

  10. #10
    Join Date
    Jun 2005
    Posts
    1723

    Re: Need help installing limit switches

    Ok that is NOT a BOB, but instead a wiring block to provide direct access to the parallel port pins. Please be very careful if you hook up something wrong you will destroy the PC parallel port. That is why most people use a BOB to protect the port. What software are you using?
    Russ

  11. #11
    Join Date
    Jun 2005
    Posts
    1723

    Re: Need help installing limit switches

    Are you using pin11 as the limit switch input?

    Write down your configuration

    Russ

  12. #12
    Join Date
    Mar 2017
    Posts
    8

    Re: Need help installing limit switches

    I have found what could be the problem. I connected the com port to the wrong ground. Yes it is in pin 11. My software is supercamxp and it seems to be ignoring the input from the limit switch.


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  13. #13
    Join Date
    Jun 2005
    Posts
    1723

    Re: Need help installing limit switches

    Yup that will do it, you need the digital ground.
    Russ

  14. #14
    Join Date
    Mar 2017
    Posts
    8

    Re: Need help installing limit switches

    Thank you again.


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