Mini Height Sensor crashes into bed during homing

Good evening. I bought one of the dc42 mini height sensor boards to use with my Duet 0.8.5 and I have followed the setup instructions David's page.

When I run the initial G30 S-1 everything works well and I get a height of 2.52mm. I entered that into my G31 command as: G31 Z2.52 P500

When I use the button on the web portal to home Z, the head moves to the center of the bed, moves down, and crashes into the bed. It never stops, so I have to hit emergency stop.


Here is my Config file:

; Ormerod 1 config file for dc42 Duet firmware
M111 S0 ; Debug off
M550 PQ	; Machine name (can be anything you like)
M551 XXXXXXXX ; Machine password (currently not used)
M540 P0xBE:0xEF:0xDE:0xAD:0xFE:0xED ; MAC Address
;*** Adjust the IP address and gateway in the following 2 lines to suit your network
M552 PXXXXXXX	; IP address (0 = use DHCP)
M554 PXXXXXXX; Gateway
M553 PXXXXXXXX ; Netmask
M555 P2 ; Set output to look like Marlin
M575 P1 B57600 S1	; Comms parameters for PanelDue

G21 ; Work in millimetres
G90 ; Send absolute coordinates...
M83 ; ...but relative extruder moves
M574 X1 Y1 Z0 S1;	; set endstop configuration (Y endstop only, at high end, active high)
M906 X800 Y800 Z2000 E800 ; Set motor currents (mA)
M563 P0 D0 H1 ; Define tool 0
G10 P0 S0 R0 ; Set tool 0 operating and standby temperatures
M92 X79.023194 Y79.207920 Z400.00 E417.00 ; Set extruder steps per mm (single nozzle) and steps for all axis
;*** If you have a dual-nozzle build, remove or comment out the previous line, and un-comment the following 3 lines
;M563 P1 D1 H2 ; Define tool 1
;G10 P1 S0 R0 ; Set tool 1 operating and standby temperatures
;M92 E420:420	; Set extruder steps/mm (dual nozzle)
;*** If you have a modulated IR probe without on-board microcontroller, change P1 to P2 in the following
M558 P1 X0 Z1 ; Use an unmodulated Z probe or an intelligent Z probe
G31 Z2.52 P500 ; Set the probe height and threshold (put your own values here)
;*** If you have a Duet board with 4.7K thermistor series resistors, change R1000 to R4700 to the following M305 commands
M305 P0 T100000 R4700 H0 L0	; Put your own H and/or L values here to set the bed thermistor ADC correction
M305 P1 T100000 B4388 R4700 H0 L0	; Put your own H and/or L values here to set the first nozzle thermistor ADC correction
;M305 P2 R4700 H0 L0	; Put your own H and/or L values here to set the second nozzle thermistor ADC correction
;*** Adjust the XY coordinates in the following M557 commands to suit your build and the position of the IR sensor
;M557 P0 X60 Y0 ; Four... 
;M557 P1 X60 Y165 ; ...probe points...
;M557 P2 X222 Y165 ; ...for bed...
;M557 P3 X222 Y0 ; ...levelling
;M557 P4 X141 Y82.5 ; 5th probe point for levelling (un-comment this if you are using a dc42 differential IR probe)
;*** if you are using axis compensation, put the figures in the following command
M556 S78 X0 Y0 Z0 ; Axis compensation here
M201 X200 Y200 Z3 E1000 ; Accelerations (mm/s^2)
M203 X7500 Y7500 Z50 E3600 ; Maximum speeds (mm/min)
M566 X600 Y600 Z30 E20 ; Minimum speeds mm/minute
M208 X210 Y260 Z190	; set axis maxima (adjust to suit your machine)
M208 X0 Y0 Z0 S1	; set axis minimum (adjust to make X=0 the edge of the bed)
M569 P0 S1
M569 P1 S1
M569 P2 S1
M569 P3 S0
;
T0	; select first hot end

And here is my Home Z file:

G91
G1 Z4 F50
G1 Y120 F1000 
G1 X110 F1000 
G1 Z-180 F50 P1
G1 Z4 F50
G1 Z-4 F50 P1
G1 Y0 F1000 S1
G1X0 F1000 S1
G90

Just as a side note, I need to move to the center of the bed to level because at the home X and Y position, the sensor is hanging off the bed. It needs to move to the middle to be able to hit the bed.

Any help would be greatly appreciated!

Your homez.g file is suitable for a microswitch, not a Z probe. See [duet3d.com].

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].