Z Probe missing trigger point



  • Hello there! I have set up all wiring on my duet wifi board, aswell as making all changes to the firmware. Everything is working as intended, but I do have some issues with the Z probe missing the trigger point.

    The Z Probe im using is 3DTouch from Geeetech which is a BLTouch clone. I have read through every post I can find related to the subject, but I still can't get my probe to avoid skipping the trigger points. From my understanding this is tweaked with the "P" parameter in the "G31 P25 X0 Y0 Z1 ; Set Z probe trigger value, offset and trigger height" command, but no matter what value I have tried so far the issue keeps on happening.

    Here is my config file:

    [[language]]
    ; Configuration file for Duet WiFi (firmware version 1.17)
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool on Wed Oct 25 2017 13:35:35 GMT+0200 (Vest-Europa (sommertid))
    
    ; General preferences
    M111 S0 ; Debugging off
    G21 ; Work in millimetres
    G90 ; Send absolute coordinates...
    M83 ; ...but relative extruder moves
    M555 P2 ; Set firmware compatibility to look like Marlin
    
    M667 S1 ; Select CoreXY mode
    M208 X0 Y0 Z0 S1 ; Set axis minima
    M208 X290 Y290 Z290 S0 ; Set axis maxima
    
    ; Endstops
    M574 Z0 S0 ; Define active low and unused microswitches
    M574 X1 Y1 S1 ; Define active high microswitches
    M558 P5 X0 Y0 Z1 H5 F120 T6000 ; Set Z probe type to switch, the axes for which it is used and the probe + travel speeds
    G31 P25 X0 Y0 Z1 ; Set Z probe trigger value, offset and trigger height
    M557 X15:265 Y15:265 S100 ; Define mesh grid
    
    ; Drives
    M569 P0 S1 ; Drive 0 goes forwards
    M569 P1 S1 ; Drive 1 goes forwards
    M569 P2 S1 ; Drive 2 goes forwards
    M569 P3 S0 ; Drive 3 goes forwards
    M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation
    M92 X80 Y80 Z400 E100 ; Set steps per mm
    M566 X900 Y900 Z12 E120 ; Set maximum instantaneous speed changes (mm/min)
    M203 X6000 Y6000 Z180 E1200 ; Set maximum speeds (mm/min)
    M201 X500 Y20 Z250 E250 ; Set accelerations (mm/s^2)
    M906 X800 Y800 Z800 E800 I30 ; Set motor currents (mA) and motor idle factor in per cent
    M84 S30 ; Set idle timeout
    
    ; Heaters
    M143 S280 ; Set maximum heater temperature to 280C
    M305 P0 T100000 B4138 C0 R4700 ; Set thermistor + ADC parameters for heater 0
    M305 P1 T100000 B4138 C0 R4700 ; Set thermistor + ADC parameters for heater 1
    M307 H7 A-1 C-1 D-1
    
    ; Tools
    M563 P0 D0 H1 ; Define tool 0
    G10 P0 X0 Y0 Z0 ; Set tool 0 axis offsets
    G10 P0 R0 S0 ; Set initial tool 0 active and standby temperatures to 0C
    
    ; Network
    M550 PJarans HEVO ; Set machine name
    M551 P********** ; Set password
    M552 S1 ; Enable network
    M586 P0 S1 ; Enable HTTP
    M586 P1 S0 ; Disable FTP
    M586 P2 S0 ; Disable Telnet
    
    ; Fans
    M106 P0 S0.3 I0 F500 H-1 ; Set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
    M106 P1 S1 I0 F500 H1 T45 ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on
    M106 P2 S1 I0 F500 H1 T45 ; Set fan 2 value, PWM signal inversion and frequency. Thermostatic control is turned on
    
    ; Custom settings are not configured
    
    

    deployprobe.g marco:

    [[language]]
    M280 P7 S10 I1
    
    

    retractprobe.g macro:

    [[language]]
    M280 P7 S90 I1
    
    

    While sending the deploy and retract macros manually it seems to almost get all the triggers, but ends up skipping one once in a while and then the alarm is triggered. When trying to run the test mode the pin goes up and down while the red LEd is constantly on(is it not supposed to turn off when the pin is down?) until it fails and released the alarm.

    I have not added any resistor to the probe and I can't seems to figure out wether I need one or not. The BLTouch seems to need a 240ohm resistor. When I got my 3DTouch it came with a 10k ohm resistor - which should be needed depending on the board, but I can't find any information on what makes the board need it or not.

    Thanks for any help!



  • Could this be related to signal interference? I got all my wires from the duet wifi and up to the extruder going side by side the whole way.

    When im doing a G29 command while the printer has not started printing anything it usually manages to get through the 9 points without failing. However when a print is started and the heat bed and extruder is active it rarely get past the third or fourth probe point.


  • administrators

    That might be due to interference, especially if it is triggering too early. Unfortunately the BLTouch is closed source, so there is no schematic that I can look at to determine how sensitive to interference it is. But if you have it connected to the Z probe input, adding a resistor of about 10K between the Z probe connector IN and 3V3 pins might help. Increasing the P parameter in the G31 command would also make it less susceptible to interference.



  • @dc42:

    That might be due to interference, especially if it is triggering too early. Unfortunately the BLTouch is closed source, so there is no schematic that I can look at to determine how sensitive to interference it is. But if you have it connected to the Z probe input, adding a resistor of about 10K between the Z probe connector IN and 3V3 pins might help. Increasing the P parameter in the G31 command would also make it less susceptible to interference.

    I have not added the 10k resistor so I can give that a shot. If that does not help then I will try to isolate the cables. Thanks for the input!



  • @dc42:

    That might be due to interference, especially if it is triggering too early. Unfortunately the BLTouch is closed source, so there is no schematic that I can look at to determine how sensitive to interference it is. But if you have it connected to the Z probe input, adding a resistor of about 10K between the Z probe connector IN and 3V3 pins might help. Increasing the P parameter in the G31 command would also make it less susceptible to interference.

    When you say add a 10k resistor to the IN connector, do you mean between the probe itself and the pin or IN between ground?


  • administrators

    I mean between the IN pin and the 3V3 pin.



  • @dc42:

    I mean between the IN pin and the 3V3 pin.

    Oh, was not familiar with "3V3" pin, but a google search said that would be the 3.3v pin. All the pins on the board is 5v that it is connected to, so the resistor would be between z probe IN and the ground next to it? (tried that without any diffrence)

    I also came over this: https://plus.google.com/113792662927481823969/posts/Sfig2jd4bvM

    Seems like the ground on the z probe connector is not attached. Is that a possibility too? I guess I got some more trial and error to do. Will post back as soon as I get somewhere.

    Edit: A little more trial and error has been done. Neither of the resistors I have tried made any diffrence. Earlier I was able to finish probing from time to time, but now it seems like the probe won't manage to even track one hit without failing. I noticed that when I retract the probe I can hear three small buzzes before it releasing the alarm.

    I might try to reset all settings and do it from scratch on another port just to be sure that its not a mistake I have made.



  • Now it seems like my 3DTouch is not tracking any signal what so ever. It can not get through any probing points at all. The z probe value never changes to "1000" upon triggering it. Deploying and retracting works, however when retracting the probe goes into alarm mode. Could my probe be defective?


  • administrators

    Does the Bltouch documentation describe what conditions put it in alarm mode? It's closed source, so otherwise it's hard to know.



  • @dc42:

    Does the Bltouch documentation describe what conditions put it in alarm mode? It's closed source, so otherwise it's hard to know.

    Not as far as I know. Can't seem to find anything on it. As the probe was working from time to time earlier with the same setup I would assume its the probe. Its not triggering at all unless its in the alarm mode.

    Will probably buy a new probe soon ish, and this time an original bltouch. Got too much finals starting in my studies now so it might take some time before I post back with an update!



  • Alright, so it looks like it was an issue with the 3DTouch. I bought a BLTouch and got it installed today. So far no steps have been skipped!


 

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