Z probe already triggered (with I0 and I1)

megaloduet

Dear Friends,
i hope it is a small issue and anyone has a advice for me.
I use a NPN Normally Open sensor but it always gives me the error:

G28 Z
Error: Z probe already triggered at start of probing move
Error: Homing failed

Hardware: Duet 2 Wifi
Board: Duet 2 WiFi (2WiFi)
Firmware: RepRapFirmware for Duet 2 WiFi/Ethernet 3.1.1 (2020-05-19b2)
Duet WiFi Server Version: 1.23

Probe: lj12a3-4-z/bx-5v

connected as described in: https://duet3d.dozuki.com/Wiki/Connecting_a_Z_probe#Section_NPN_output_normally_open_inductive_or_capacitive_sensor

No matter if I invert the probe via M558 or not. (If I start homing with a piece of metal below the sensor it starts)

See my Tests and config:

config:

; Z-Probe
;M558 P1 C"zprobe.in" H5 F120 T6000
M558 P5 C"zprobe.in" H5 F120 T6000 I1         ; set Z probe type to unmodulated and the dive height + speed
;G31 P500 X0 Y0 Z2.5   
G31 X0 Y0 Z2.5                           ; set Z probe trigger value, offset and trigger height
M557 X15:215 Y15:195 S20                       ; define mesh grid

Homez.g

; homez.g
; called to home the Z axis
;
; generated by RepRapFirmware Configuration Tool v3.1.3 on Mon Jun 22 2020 09:53:01 GMT+0200 (Mitteleuropäische Sommerzeit)
G91              ; relative positioning
G1 H2 Z5 F6000   ; lift Z relative to current position
G90              ; absolute positioning
G1 X15 Y15 F6000 ; go to first probe point
G30              ; home Z by probing the bed

The web Ui confirmes that the probe is connected and reads the values.
Default : ZPROBE 1000
With piece of metal below: ZPROBE 0

Tests:
Results with I0/I1 when homing:

G31 Readings with I0 and I1

aidar

From wiki - Invert the input by prefixing the input pin (C parameter) with ! character, when using an NPN output inductive or capacitive sensor or using an NO switch (not recommended, use a NC switch instead).

I1 parameter does not work for firmware 3.x, so try M558 P5 C"!zprobe.in" H5 F120 T6000

megaloduet

Thank you, you are a wizard! It works perfectly!

aidar

You welcome, but for future reference the icon that looks like book on top of your screen (Duet3d documentation) makes you a wizard as well, if you read it.