DC's IR probe

  • Hi,

    I'm trying to commission my delta to use DC42's IR probe and I'm having some issues for a few days now.

    I have the probe installed and it's flashing 4x on boot up.
    It reports correct values on the PanelDue. Wiring is correct and it works… a little.

    When I command G30, the printer moves down and triggers correctly.
    When I use G32 (bed.g) the probe wont trigger (it turns red) but doesn't stop.

    I want the probe to do my delta calibration and bed leveling, but I need it to function first.
    Any help is greatly appreciated. Can someone post their bed.g or let me know what i'm doing wrong?


    ; bed.g
    ; called to perform automatic delta calibration via G32
    ; generated by RepRapFirmware Configuration Tool on Mon Dec 18 2017 11:48:15 GMT-0600 (Central Standard Time)
    ; Clear any bed transform
    ; Probe the bed at 6 peripheral and 3 halfway points, and perform 6-factor auto compensation
    ; Before running this, you should have set up your Z-probe trigger height to suit your build, in the G31 command in config.g.
    G30 P0 X0 Y124.42 H0 Z-99999
    G30 P1 X100.43 Y57.98 H0 Z-99999
    G30 P2 X100.43 Y-57.98 H0 Z-99999
    G30 P3 X0 Y-124.42 H0 Z-99999
    G30 P4 X-108.25 Y-62.5 H0 Z-99999
    G30 P5 X-108.25 Y62.5 H0 Z-99999
    G30 P6 X0 Y61.46 H0 Z-99999
    G30 P7 X46.77 Y-27 H0 Z-99999
    G30 P8 X-54.13 Y-31.25 H0 Z-99999
    G30 P9 X0 Y0 H0 Z-99999 S6
    ; Use S-1 for measurements only, without calculations. Use S4 for endstop heights and Z-height only. Use S6 for full 6 factors
    ; If your Z probe has significantly different trigger heights depending on XY position, adjust the H parameters in the G30 commands accordingly. The value of each H parameter should be (trigger height at that XY position) - (trigger height at centre of bed)

  • I just tested the following with the same result.

    Probing starts, machine moves towards the bed. As I trigger the sensor by hand the lights come on, but machine continues downward and ignores the sensor trip.

    G30 P0 X10 Y10 X-9999 (doesn't stop)
    G29 S0 (doesn't stop)
    G32 (or from PanelDue) (doesn't stop)

    This is the weird part. If i do a G30 with no parameters… it's stops as expected.

    Please help, my brain hurts now.


  • administrators

    In config.g check that you have set the correct probe type (P1) in the M558 command, and the correct threshold (P500) in the G31 command.

    Which firmware version are you using?

  • Hi David,

    My config.g does have those items in it.

    ; Endstops
    M574 X2 Y2 Z2 S0 ; Define active low and unused microswitches
    M558 P1 X0 Y0 Z0 H5 F1000 T2000 I0 ; Set Z probe type to switch, the axes for which it is used and the probe + travel speeds
    G31  P500 X0 Y0 Z1.5 ; Set Z probe trigger value, offset and trigger height
    M557 R130 S20 ; Define mesh grid

    Firmware is:

    Duet WiFi 1.0
    1.19.2 (2017-09-01) -Firmware
    1.19.2 - WiFi server
    1.19.3 - Web Interface

  • I should mention that I do not have my thermistors or heaters hooked up yet, so they are reading 2000.
    Everything else is operational, machine homes and jogs and can dry run gcode.


  • administrators

    Does the IR sensor trigger reliably (i.e. the LED turns red) before the nozzle touches the bed, at all XY positions of the effector? If you have effector tilt that varies with XY position, then the trigger height will also vary with position.

  • The lights come on when triggered during any probing call but the machine will ignore it.
    The only time I can get it to work correctly is when I send a G30 with nothing else (P… X... Y...)

    with G30, the head moves down and begins to slow as it reaches the bed and then stops and reports the distance to the DWC.
    Like it's supposed to.

    When i send G29 or G32, lights come on, but will not stop...

    When idle i can move a paper under the sensor and I can see the numbers change on the PanelDue and DWC.

    Really scratching my head, Everything looks to be correct, and why it works OK with G30 but not anything else is beyond me.
    This is the last thing I need to do to get the printer running. My boss is starting to give me side eyes.

    Do you think a fresh firmware install is needed??

  • administrators

    Perhaps the probing move isn't starting because you have then M665 H parameter set too high, so that the initial positoining move is positioning the effector too low. Try this:

    1. With all 3 carriage right up against the endstops, measure the height of the nozzle above the bed to an accuracy of +/-5mm. Put this figure in the H parameter of the M665 command.

    2. In your M558 command temporarily increase the H (dive height) parameter to 30. You can put it back to 5 when you have auto-calibrated and you have the correct H and R parameters in your M665 command.

  • You get a biscuit today!!

    That did the trick! thank you so much… I would have never figured that out.


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