• Hiya,
    Can some one provide a picture of the bltouch's connections to the duet wifi.

    As well as a picture of the one of the pins being shorted and safe for 3.3v.

    I have ordered a chinese one from aliexpress.

  • for the 3 pin connections, i recommend using a bigger single jack _maybe an 8 pin)rather than a 2 pin and a 1 pin. I did that initially and had connection issues as the connectors have a bit of slop in them. Machine movement would cause bl touch to alarm or cut off which is how i found the lose connections…

  • yup, me too I used a 1 pin and 2 pin connector. I believe it was the single pin connector that was causing me so much grief. 8 pin with only 3 wires seems to be more reliable. I suspect the crimp also had something to do with it. I have a crimp tool but much prefer a decent pair of needle nose. i seem to get better results that way. surprising considering i have built thousands of cables over the years and am very familiar with crimp tools etc. maybe mine is just a cheap1?

  • @CaLviNx That is probably the most clearest article i've ever seen, I think the wiki needs more pictures and screenshots, Thank you

    @FrankNPrinter Lol, I have already wired a connection like the dupont your using, so when i finally get his i would probably use that one Thanks again

  • Finally got the Bltouch(aliexpress knock of)
    Heres a couple of pictures off it,

    Which version of the bltouch do i have
    if its the old one can someone provide a diagram of how to attach the 240ohm resistor

  • HI,

    it is as shown on the pic. you need to short(circuit) the black and the white wire. you can do this at the connector end don't start messing at the pcb-end


  • can i just poke the resistor in to the dupont connector like in the diagram, or would i need to do some soldering

  • I doubt anybody will publicly condone doing that, but it will work. But make sure it doesnt Fall off. Things is (and i know very little about these things) that those wires send the signal back at 5V but it's designed to receive only 3.3 - what happens to the board (or the bltouch) if it is jolted with too high a voltage i cannot tell you.
    Which reminds me, first measure the resistor to verify 240Ohm, Second when attached measure again (on the conectors) if the resistance is indeed 240Ohms between the pins.

    The kit i Got (supposedly original but….) had two resistors one ten ohm and one two-forty i gather using the wrong one would be bad.

  • Hey.

    My BLTouch is just like this one in the photos and it works as is with the Duet without the resistor. However if I poke the 240ohm resistor in the black/white connector housing to test it's use, the output on the pins is much lower than the 3.3 volts, in fact is about 1.6 volts and the setup no longer works.
    Without the resistor the voltage is 3.9 volts.

    I've asked in the other topic as well if this 3.9 volts is a problem, but for those in this topic, is your BLTouch in the photo above working with or without the resistor?



    p.s. Little more testing and the voltage on triggering the BLTouch jumps to 4.9 volts and then quickly drops to 3.9 volts on my DVM

  • hiya,
    i managed to see some love from the bltouch however the servo starts to loop continuessly after testing it with the M401 cammand, i.e. produdes then retracts as soon as i touch it.

    at one point the red light on the bltouch starts blinking,

    This is with the reisistor when i get a chance i test it without the resistor, if it works out of the box i would be very happy

  • i wonder if the 3.9v @coolice would do any harm

  • Ok i managed to get it working howrver when i go into test mode the pin keeps portruding continuesly and doesn't stop

    M280 P3 S60 I1
    can someone describe which letter means what.

    how many times does this command deploy the probe?
    kind regards

    i got mine working without the ground pin

  • @npm1:

    i wonder if the 3.9v @coolice would do any harm

    Hey buddy.

    I'm not sure mate, not been given an actual answer if that would harm the Duet.
    In the meantime I've series linked 3x 2k resistors and got the black and white wires now giving me 3.2x volts and have the setup running on that.

    I had a problem with the posted BLTouch setup instructions not making the mesh bed levelling work for me, but I've manged to fix it I think by adding a missing line of code in the bed.g file from memory. It now homes, then when I select the mesh bed levelling works it's way from point to point over the bed proving away nicely.
    I just need to check it now as the printer is so new still I've not yet printed with it 😕 Hoping to this weekend now.

    I'm watching this topic as well for tips 🙂
    Your BLTouch is exactly the same as mine a Classic, what voltage do you see on your black and white wires if I may ask?


  • Ok so i managed to get the bltouch working as per the instructions provided by CaLviNx
    the wiring excludes the black wire, when the black wire is in the ground the readings don't work,

    I can now click on automatic bed compensation, which performs the probing without any problem,
    When the G32 command is struck it gives a graph which appears uneven. More to come on this when I get home.

    the issue is when i perform G29. when i activate G29 the probe doesn't protude.

  • I would probably show a video

  • administrators

    In firmware 1.18 and earlier, G29 doesn't automatically deploy the probe, so you need to wrap it in a macro. It does deploy the probe in firmware 1.19.

  • @npm1:

    Ok i managed to get it working howrver when i go into test mode the pin keeps portruding continuesly and doesn't stop

    M280 P3 S60 I1
    can someone describe which letter means what.

    how many times does this command deploy the probe?
    kind regards

    i got mine working without the ground pin

    These are the possible commands/combinations :
    M280 P0 S10 ; pushes the pin down
    M280 P0 S90 ; pulls the pin up
    M280 P0 S120 ; Self test – keeps going until you do pin up/down or release alarm
    M280 P0 S160 ; Release alarm

    When using a probe mounted on a real servo, then the S parameter is the angle in degrees that a servo should move to.
    Here it is used to pass a command to the probe.


  • Hi,

    I have a Bltouch, and after cut the track and lower the voltage in white pin, I have measured with a multimeter, and the tension is 3.1…. It's suficient for fire Z Probe?

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