Capacitive npn sensor

Bravo6

Hi. I have fitted a NPN capacitive sensor to the duet wifi. I have powered it 12v from psu and signalled from z min. it works fine on homing but when I go G29 it either says insufficient points probed or error probe already triggered. If I home and then run a M119 it shows Error: Z probe already triggered before probing move started.
I'm probably an idiot and it's something simple. I have set the probe to mode 7 for the z input.

A Former User

Wiki suggest using mode 5 and adding a diode?

https://duet3d.dozuki.com/Wiki/Connecting_a_Z_probe#Section_NPN_output_normally_open_inductive_or_capacitive_sensor

Stephen6309

@bravo6 Raise the Z enough for it not to be triggered? On my printer, it needs to start at least 5mm above the bed to be not triggered.

A Former User

Maybe i'm readign this wrong, but you're saying you're using mode 7, which is the z-endstop as input for the npn sensor, G29 doesn't work.

You need to run G28/home before G29, and that would rely on the z-endstop, leaving the sensor triggered. So maybe Stephen is right, try raising your Z axis and look at web interface Settings -> Machine configuration -> Endstop hit and keep raising Z until it changes to no, and try again.

If that helps, just add G0 Z5 (or whatever value instead of 5 that your switch no longer triggers) to bottom of homeall.g. Another suggestion is to increase your dive height in the M558 command to see if it will raise Z despite being triggered before probing.

Bravo6

Thanks all for the responces. Will try dropping the bed out of range but the led is off on the sensor. I did g28 then g29 from past marlin experiences..

Phaedrux

What is in you homeall.g?

Bravo6

@phaedrux ; homeall.g
; called to home all axes
;
; generated by RepRapFirmware Configuration Tool v2 on Sun May 12 2019 19:03:49 GMT+0100 (British Summer Time)
G91 ; relative positioning
G1 Z5 F800 S2 ; lift Z relative to current position
G1 S1 X-265 Y-265 F800 ; move quickly to X and Y axis endstops and stop there (first pass)
G1 X5 Y5 F900 ; go back a few mm
G1 S1 X-265 Y-265 F800 ; move slowly to X and Y axis endstops once more (second pass)
G1 S1 Z-355 F800 ; move Z down stopping at the endstop
G90 ; absolute positioning
G92 Z0 ; set Z to axis minimum (you may want to adjust this)

; Uncomment the following lines to lift Z after probing
G91 ; relative positioning
G1 S2 Z5 F100 ; lift Z relative to current position
G90 ; absolute positioning

Bravo6

@phaedrux Just trying new settings with mode 5 selected and M558 i1

Bravo6

@bravo6 yep will do thanks