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IndustryArena Forum > OpenSource CNC Design Center > Arduino > No LIM status. Unable to troubleshoot limit switches
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  1. #1
    Join Date
    Oct 2006
    Posts
    5

    No LIM status. Unable to troubleshoot limit switches

    Hello there.
    I am using Arduino UNO , GRBL 1.1h and CNC shield on small desktop CNC. I am trying to troubleshoot limit switches but cannot get LIM output on terminal staus string . Here are settings

    $0=10
    $1=25
    $2=0
    $3=7
    $4=0
    $5=0
    $6=0
    $10=19
    $11=0.010
    $12=0.002
    $13=0
    $20=0
    $21=0
    $22=1
    $23=3
    $24=25.000
    $25=500.000
    $26=250
    $27=1.000
    $30=1000
    $31=0
    $32=0
    $100=23.500
    $101=50.000
    $102=400.000
    $110=200.000
    $111=200.000
    $112=200.000
    $120=10.000
    $121=10.000
    $122=10.000
    $130=200.000
    $131=120.000
    $132=50.000
    ok


    $10 is set to 19 , as per recommendations from public forums, but whatever I am doing I can't see any status in the output.
    I am using TerraTerm at this point to communicate with GRBL

    typical output is like that

    ?<Alarm|MPos:0.000,0.000,0.000|Bf:15,128|FS:0,0>
    ?<Alarm|MPos:0.000,0.000,0.000|Bf:15,128|FS:0,0>
    ?<Alarm|MPos:0.000,0.000,0.000|Bf:15,128|FS:0,0>
    ?<Alarm|MPos:0.000,0.000,0.000|Bf:15,128|FS:0,0>
    ?<Alarm|MPos:0.000,0.000,0.000|Bf:15,128|FS:0,0>
    ?<Alarm|MPos:0.000,0.000,0.000|Bf:15,128|FS:0,0|WC O:0.000,-1.000,0.000>
    ?<Alarm|MPos:0.000,0.000,0.000|Bf:15,128|FS:0,0|Ov :100,100,100>
    ?<Alarm|MPos:0.000,0.000,0.000|Bf:15,128|FS:0,0>

    Any ideas, folks? Any help wil lbe gratly apreciated

  2. #2
    Join Date
    Mar 2015
    Posts
    409

    Re: No LIM status. Unable to troubleshoot limit switches

    To enable the limit switches do the following:


    • Enable hardware limits (set $21 to 1)
    • For normally open sensors (NO) set $5 to 0
    • For normally closed sensors (NC) set $5 to 1 and connect the X-limit and Z-limit pin to GND, if there are no limit switches connected to them.

  3. #3
    Join Date
    Oct 2006
    Posts
    5

    Re: No LIM status. Unable to troubleshoot limit switches

    Thanks. Switches (HW micro switches - NO ) itself are connected to the shield, I just did as you recommended, but still see no LIM output in the status line.

  4. #4
    Join Date
    Mar 2015
    Posts
    409

    Re: No LIM status. Unable to troubleshoot limit switches

    What CNC shield are you using?

  5. #5
    Join Date
    Oct 2006
    Posts
    5

    Re: No LIM status. Unable to troubleshoot limit switches

    Something like that "CNC Shield Expansion Board V3.0+UNO R3 Board with usb for Arduino+4pcs Stepper Motor Driver A4988 Kits for Arduino" I bought this from eBay a while ago. Do you think this is shield issue?

  6. #6
    Join Date
    Mar 2015
    Posts
    409

    Re: No LIM status. Unable to troubleshoot limit switches

    Could be, a RAMPS shield doesn't support hardware limits due to the pin mapping RAMPS choozed. I have a (2) Keyes Uno cnc shield where the step and enable pins are swapped, etc.
    If you have programmed the arduino uno your self, you had to chooze the right grbl version.

    Save your grbl configuration and try this one. It comes from an arduino uno that uses hardware limits (lathe). Ignore the errors you see, they are caused because this is a GRBL-L configuration file.

    If that doesn't help, remove a limit switch and simulate the switch by connecting the limit switch input to GND

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