BL Touch questions



  • I have now got the stage of testing Z homing with a BL Touch Smart however I seem to be in the same space as "Peirof" in that I can make the BLT respond correctly to the commands M401, M402 and it runs the M280 test and reset routines so I'm happy that the servo side is set up properly but I cant seem to make any sense of the ZProbe bit.

    When I try to do a G30 or Home Z the Duet stops and reports that the Z probe is triggered before it starts moving the Z axis.

    I followed the instructions in the Wiki and checked the wiring all seems OK however the Zprobe value displayed on the Webpage always stays at 1000 no matter what state the probe is in and is shown on a pink background like there is an error of sorts. Its the same if I remove all connections to the Z-probe and the same if I short "Zstop" to either the "Gnd" or +3.3V on the board. The board does recognise a trigger when I short "Zstop" to "Gnd" as the Z probe endstop LED changes. I can also just barely see the LED flash when the BLT probe is triggered so it looks like the hardware side of things is happy but there's something I'm missing in the config file.

    Grateful for any help trying to sort this out. Here is my config file:

    Configuration file for Duet WiFi (firmware version 1.17 to 1.19)
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool on Wed Nov 01 2017 22:28:59 GMT+0100 (W. Europe Standard Time)

    ; 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
    M307 H3 A-1 C-1 D-1 ;

    M667 S1 ; Select CoreXY mode
    M208 X0 Y0 Z0 S1 ; Set axis minima
    M208 X290 Y290 Z390 S0 ; Set axis maxima

    ; Endstops
    M574 Z0 S0 ; Define active low and unused microswitches
    M574 X2 Y1 S1 ; Define active high microswitches
    M558 P5 X0 Y0 Z1 H5 F100 T2000 ; Set Z probe type to BLTOUCH, the axes for which it is used and the probe + travel speeds
    G31 X0 Y0 Z0 P25 ; Set Z probe trigger value, offset and trigger height
    M557 X15:275 Y15:275 S20 ; 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 S1 ; Drive 3 goes forwards
    M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation
    M92 X80 Y80 Z2000 E420 ; 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 Y500 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 S245 ; Set maximum heater temperature to 245C
    M305 P0 T100000 B4138 C0 R4700 ; Set thermistor + ADC parameters for heater 0
    M305 P1 T100000 B4725 C7.060000E-8 R4700 ; Set thermistor + ADC parameters for heater 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 PH.EVO ; Set machine name
    M552 S1 ; Enable network
    M587 S"" P"********" ; 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

    ; Fans
    M106 P0 S0 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



  • Surely it is the least indicated person to answer you … But I am ideas that you can try...

    First... When you power on Duet, Bltouch makes a self test (deploy, retract, deploy, retract)... And if makes this test... BlTouch, is blinking, or with internal light (on or off), or with internal small blue led power on?



  • On start up the BLT does a self test of deploying and retracting the probe twice. The red internal LED is on and the probe finishes in the retracted position. I have another BLT on my old Tevo Tarantula (running Marlin) that does exactly the same thing on power up so all looks good from that perspective.



  • So I changed M558 P5 X0 Y0 Z1 H5 F100 T2000 to be M558 P4 X0 Y0 Z1 H5 F100 T2000 and used the E0 Stop connector now everything works as it should and I have successfully homed Z for the first time. Is there an issue with the Z Stop connection?


  • administrators

    If you use P5 in your M558 command, the sensor must be connected to the Z Probe connector, not the Z Endstop connector.



  • Thanks all becomes clear now. It was right there in black and white in the wiki but just didn't see it no matter how many times I looked at it. 🙂 (Probably coming from a MKS Base 1.4 where the BLT does connect as a Z Endstop - thats my excuse anyway). Peirof - this might be your solution too!



  • I try later, thanks.. I will post feedback


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