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Problem with Gradus M1 Pro probe input

Discussion in 'CNC Mills/Routers' started by scottlbaker, Aug 12, 2019.

  1. scottlbaker

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    I'm trying to bring up a Gradus M1 Pro board on a CNC router. Using the Universal Gcode Sender program, I can move the motors OK, but the G38.2 probe command doe not work correctly. The probe motion often stops early before the probe contacts. I suspect noise on the probe input is causing an early/false trigger. In my test setup, the probe wire is short and not run close to anything noisy.

    >>> G38.2 z10 F1
    [PRB:0.000,0.000,6.368:1]
    ok

    I contacted Panucatt about this and they mentioned a possible mod of adding a filter cap to the probe input, but so far they have not provided any details.

    Has anyone run into this problem and if so what was the fix?

    Thanks,
    Scott
     
  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

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    Yip, going to need a 0.1uf 6.3v cap over the input (one leg to gnd, one leg to probe input) as near the board as possible. A 10k pullup between 5v and probe input will help even more:
    Solving Endstop Woes With A Simple Analog Filter is a great article on the topic
     
  3. scottlbaker

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    Thanks Peter. I added a .1uF cap and a 10k pullup to 5V and that fixed the problem.
     

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  4. Scotty Orr

    Scotty Orr Journeyman
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    I know this is an old topic, but I just took advantage of the flash sale on the OpenBuilds XYZ probe. If using it on the M1 Pro, do I still need to make these modifications, or is the filtering built into the XYZ probe? I plan on hooking up the 5V for led and filtering to the same header as the OP did.
     
  5. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Filters are built into the Blackbox, not the Probe. Noise is on the wire, so no use filtering on the far end, the controller should clean up the incoming signal.
     
  6. Scotty Orr

    Scotty Orr Journeyman
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    OK, so I should add the cap and resistor to my M1 pro. I just wondered from what I read in the XYZ docs about connecting to generic controllers:

    I assumed that meant noise filtering circuitry on the XYZ Plus itself.
     
  7. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    There is, but if (as the person earlier in the thread) the EMI is introduced into the cable, you need the cap and pullup near the Controller side.

     
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