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Help With Installing Limit Switches to Chinese GRBL 0.9j

Discussion in 'CNC Mills/Routers' started by 1759adam, Jun 16, 2019.

  1. 1759adam

    1759adam New
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    New to the forum and I've just completed assembly and modification of a Chinese CNC Router.

    I have limit switches mounted now on 2 on X, 2 on Y and 1 on the top of Z, but I can't figure out how to wire them to my Chinese 0.9j GRBL board.

    I have looked at many diagrams for wiring in series, but my GRBL Board has 3 pins on each of the X,Y and Z limit inputs. These are marked + - and S on the backside of board.

    Can anyone suggest how I should wire a Normally Closed circuit to this with my 5 Micro Switches, please.....?

    Image of mystery board attached with Limit Pins to the right of image.

    Many thanks in advance,

    Adam Chinese GRBL 0.9 Board.jpg
     
  2. Giarc

    Giarc Master
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    I am not familiar with that board. Have you tried the manufacturer's customer service yet? They may be in the best position to help you.
     
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  3. Christian James

    Christian James Veteran
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    I don't know that board either but the 3rd input pin (S) must be the signal pin and would be used together with the +/- pins for an optical sensor connection. If you are using micro-switches however, then just use the S and ground (-) pin, the "S" to "normally closed" on the switch and ground to "C" on the switch.
    Just do not wire it wrong ( keep away from the + pin - that's for the optical sensor)

    Have a look here at the series and parallel switch wiring..

    gnea/grbl
     
    #3 Christian James, Jun 18, 2019
    Last edited: Jun 18, 2019
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  4. 1759adam

    1759adam New
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    Thanks for replies. I'll get to work. Regards,
    Adam
     
  5. 1759adam

    1759adam New
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    Thanks for your advice. I've connected 1 micro-switch as you suggested and it's now working. To get left and right limits on X Axis, should I connect Micro-Switches together via COM pins, and to -, and wire both NC pins together into S on the board?

    Many thanks,

    Adam
     
  6. Alex Chambers

    Alex Chambers Openbuilds Team
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    For Normally Closed switches you need to wire two switches on the same axis in series - signal (control board) to nc (switch one), common (switch one) to nc (switch two), common (switch two) to ground (control board)
    Alex.
     
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  7. 1759adam

    1759adam New
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    Many thanks, I was about to ask if this diagram is correct, but I think you have already described.
     

    Attached Files:

  8. Christian James

    Christian James Veteran
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    Here's another drawing attached cnc_limit_switch_c3.png
     
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  9. Alex Chambers

    Alex Chambers Openbuilds Team
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    Bear in mind however that is for normally open limit switches.
    Alex.
     
  10. Christian James

    Christian James Veteran
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    Yes Alex, and I believe pin 12 should be used and not pin 11.
     
  11. Alex Chambers

    Alex Chambers Openbuilds Team
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    Can't help with that one @Christian James, but hopefully someone who is familiar with that set-up will clarify that before someone tries to use that diagram. I think @sharmstr has used an arduino and may be able to help.
    Alex.
     
  12. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Refer to the Grbl wiki for all the pin information gnea/grbl
     
  13. Christian James

    Christian James Veteran
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    Yes Peter, that confirms what I thought and how mine is wired. Pin 11 has been grabbed for use by the spindle while the Z switch pin has been shoved onto pin 12
     

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