BL Touch probe input not working



  • I'm replacing a functioning IR probe on a Core XY that was connected to the probe port on Duet Wifi. I followed the wiki, cut the 3.3V trace, and hooked up exactly as shown. I setup config.g as described. When testing, the servo works fine and the probe extends and retracts and goes into test mode properly. However, the Z-probe display in DWC (upper right) always shows 1000.

    I've checked my wiring - I clipped the BL Touch leads and soldered extensions to my Duet. I'm using the proper 4pin connector on the probe port with signal and ground wires connected as described.

    Any debugging suggestions so I can determine if I got a bad BL Touch or if something else is wrong?

    cheers,
    Michael



  • The pulse length is very short for the BLTouch, but if you move the nozzle way from the bed a decent amount and try to probe can you trigger it manually with your hand?



  • Are you using heater pin 3 or7?
    Are they unbound in your config.g?
    Are you using probe type 9?



  • I can but the probe status never changes.

    I just tested with my Fluke and:

    M280 P3 S10 I1 - I measure .001VDC

    M280 P3 S90 I1 - I measure .002VDC

    I can go back and forth and it is completely reproducible. Bad BL Touch?



  • I hooked up exactly as in the wiki on heater 3. Here's my config.g

    ; BL Touch config
    M307 H3 A-1 C-1 D-1
    M558 P5 X0 Y0 Z1 H5 F100 T2000 I1
    G31 X12 Y28 Z0 P25

    Probe type 9??? Maybe that's it. Wiki shows P5



  • Running 1.21 release



  • The wiki hasn't been updated with the details of probe type 9 yet. But it's new in 1.21 and is specifically for the BLTouch. Setup is mostly the same but it will now automatically call the deploy and retract macros to extend and retract the probe when needed.

    Here's what I ended up with in my config to get it running consistently.
    [c]
    ; ############################
    ; 3 - ENDSTOPS AND ZPROBE
    ; ############################

    M574 X1 Y2 S0 ; Set active-low switches, low end endstop for X, high end endstop for Y, add Z2 for Zmax
    M574 Z1 S2 ; Use zprobe and home to min
    M307 H3 A-1 C-1 D-1 ; Unbind heater 3 pins for probe use.
    M558 P9 X0 Y0 Z1 H5 F100 T4000 A10 R0.5 S0.008 ; P9 for BLTouch, dive height 5mm, probe at 100mm/s, travel 4000mm/s, probe until 2 consecutive probe results are to within S up to 10 probes, pause 0.5s, Reprobe until 0.008 repeatability
    G31 X-42 Y-2 Z1.8 P25 ; probe offset from nozzle, p is trigger value, set low for bltouch, set Z=0 for testing (z height is 1.8006 after calibration)
    M557 X20:310 Y0:285 S15 ; Define mesh grid
    M376 H20 ; Taper off compensation over 20mm of height[/c]



  • We'll, changing to P9 did not help. I still see the probe value at 1000 deployed or not.



  • The LED on the touch is showing the right thing.

    Ok, should I delete the deploy and retract macros that I so painstakingly 😉 created?



  • It won't change when deployed; only when triggered, and it may not be noticeable in the DWC because it's only a short flash.

    Does it stop the bed when triggered though? If so, it should be good to go.

    What happens if you move the nozzle to the bed, set Z=0, move up 10mm, and issue G30 S-1?



  • @mhackney:

    The LED on the touch is showing the right thing.

    Ok, should I delete the deploy and retract macros that I so painstakingly 😉 created?

    The deploy and retract macros should only have the servo commands to deploy and retract the pin.



  • I am commissioning and don't want to slam it into the bed. The wiki says to do these tests and watch the probe value change to 0 and then 1000 when triggered. Mine is always 1000.



  • If you set the probe into test mode and touch the probe what does the DWC show?



  • the macros do only have the servo commands but are they no longer needed with 1.21 or should I leave them.



  • P120 test mode? if so, it stays at 1000 while the probe extends and retracts until cleared.



  • @mhackney:

    the macros do only have the servo commands but are they no longer needed with 1.21 or should I leave them.

    They still need to be there, you just don't have to call them in other macros now, you can just use M401 and M402.



  • Hmm, I have this for endstops: M574 X1 Y1 Z0 S1



  • @mhackney:

    P120 test mode? if so, it stays at 1000 while the probe extends and retracts until cleared.

    But does it change when you touch the pin to simulate a trigger?



  • @mhackney:

    Hmm, I have this for endstops: M574 X1 Y1 Z0 S1

    Take out the Z0 and add another command to specify the Z

    like so

    [c]M574 X1 Y2 S0 ; Set active-low switches, low end endstop for X, high end endstop for Y, add Z2 for Zmax
    M574 Z1 S2 ; Use zprobe and home to min[/c]



  • The Z-probe status in the DWC isn't very helpful with the BLTouch. It triggers and releases so fast it's hard to see it flash.

    But as long as it actually stops the bed from traveling it'll work just fine.


 

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