Z-PROBE Triggers properly, but does not turn off

  • I have an NPN resistive z probe that triggers properly on my aluminum bed, but as soon as it is triggered, it stays on, both the DWC reading and the LED on the sensor stay on until manually reset.

    wired as described in wiki (mode4, bat43 w cathode line toward sensor connected to black output wire, grounded blue wire, brown wired directly to 24v. Both EO and ZPROBE tried)

    Once the Duet is reset, it shows as untriggered and reads correctly (0 for away, 1000 for close). It will stay off until triggered again and then stays on for good. This is repeated every time, I tried and have the same problem with both E0 and Z Probe pin positions, and it happened the same with both BAT43 and 1N4148. If I1 is used (0 when off, 1000 when triggered, stays at 1000 when it is off bed) If I0 (default) is used (1000 when off, 0 when triggered, stays at 0 when it is off bed).

    I also have a mechanical z switch. but that seems to work fine and it does not stay on or change due to z probe hookup. I use the mechanical z stop to homeall and homez. I was able to print without the probe, so all other hardware/settings seem to be working.

    Previously worked on zonestar zrib board. Board fried, not sure why, bought a duet wifi.
    using 1.21 firmware.


    G90 ; Send absolute coordinates...
    M83 ; ...but relative extruder moves

    ; Network
    M550 PNinjaD ; Set machine name
    M552 S1 ; Enable network
    M587 S"XXXXXXXX" P"XXXXXXXX" ; Configure access point. You can delete this line once connected
    M586 P0 S1 ; Enable HTTP
    M586 P1 S0 ; Disable FTP
    M586 P2 S0 ; Disable Telnet

    ; Drives
    M569 P0 S0 ; Drive 0 goes forwards (X)
    M569 P1 S0 ; Drive 1 goes backwards (Y)
    M569 P2 S1 ; Drive 2 goes forwards (Z)
    M569 P3 S0 ; Drive 3 goes back (E0)
    M569 P4 S0 ; Drive 4 goes back (E1)
    M350 X16 Y16 Z16 E16:16 I1 ; Configure microstepping with interpolation
    M92 X80 Y80 Z400 E96:96 ; Set steps per mm
    M566 X900 Y900 Z12 E120:120 ; Set maximum instantaneous speed changes (mm/min)
    M203 X6000 Y6000 Z3000 E1200:1200 ; Set maximum speeds (mm/min)
    M201 X400 Y350 Z250 E250:250 ; Set accelerations (mm/s^2)
    M906 X800 Y800 Z800 E800:800 I30 ; Set motor currents (mA) and motor idle factor in per cent
    M84 S30 ; Set idle timeout

    ; Axis Limits
    M208 X-30 Y-8 Z0 S1 ; Set axis minima
    M208 X300 Y300 Z400 S0 ; Set axis maxima

    ; Endstops
    M574 X1 Y1 Z1 E0 S0 ; Set active low endstop

    ;Pre-Z Probe
    M671 X-18:-18:250:250 Y20:287:287:20 S1.0 P0.5 ;adj screw locations - if this is z probe or nozzle, I don't know.

    ; Z-Probe
    M558 P4 H6 X0 Y0 Z1 I1 F150 T3500 ; Set Z probe type to switch and the dive height + speeds ------ I1
    M557 X-18:250 Y25:287 S25 ; Define mesh grid
    G31 P600 X0 Y0 Z2.5 ; Set Z probe trigger value, offset and trigger height

    ; Heaters
    M305 P0 T100000 B4138 C0 R4700 ; Set thermistor + ADC parameters for heater 0
    M143 H0 S120 ; Set temperature limit for heater 0 to 120C
    M305 P1 T100000 B4138 C0 R4700 ; Set thermistor + ADC parameters for heater 1
    M143 H1 S280 ; Set temperature limit for heater 1 to 280C

    ; Fans
    M106 P1 S1 I0 F500 H1 T45 ; Set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off -M106 P0 S0.3 I0 F500 H-1
    M106 P1 S1 I0 F500 H1 T45 ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on M106 P1 T45 H1
    M106 P2 S1 I0 F500 H1 T45 ; Set fan 2 value, PWM signal inversion and frequency. Thermostatic control is turned on

    ; Tools
    M563 P0 D0 H1 ; Define tool 0
    G10 P0 X0 Y0 Z0 ; Set tool 0 axis offsets
    G10 P0 R0 S20 ; Set initial tool 0 active and standby temperatures to 20C
    M563 P1 D1 H1 ; Define tool 1
    G10 P1 X0 Y0 Z0 ; Set tool 1 axis offsets
    G10 P1 R0 S20 ; Set initial tool 1 active and standby temperatures to 20C

    ; Automatic saving after power loss is not enabled
    M911 S20.0 R23.0 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000"

    ; Custom settings are not configured

    ; Miscellaneous
    T0 ; Select first tool

  • administrators

    If you disconnect the sensor output wire from the Duet, does the sensor LED still remain on for good after it has been triggered once? If so, that would confirm that it is a problem with the sensor. Did your old board also use 24V power, or is this the first time you have run the sensor from 24V?

  • As per your description, it IS a problem with the sensor (npn z probe).

    I had both wires connected to E0, homed Z, and LED came on.
    I pulled the black wire (z probe output wire) off duet wifi, zprobe LED stayed on. I raised the z high. Still the LED was on.

    Would this failure be why the reading is either 0 or 1000. I would assume there should be different values if it were working properly. Is that correct?

    Yes my old board was 24v zonestar zrib and the sensor worked properly. Although that board fried for an unknown reason, so maybe the frying caused it's zprobe failure, or the z probe failure caused the frying of my mainboard.

  • administrators

    If the Z probe produced a digital output, the only readings you will get will bge 0 and 1000. It's only for analog-output sensors that you can get readings in between.

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