Some have suggested: to check if the state.status is "processing" when homing.

Problem: It is always "processing" the moment the print is started, so homing never occurs during the print. Which means, you start the print and then get many not homed errors.

I set a global variable in config.g and checkit in the homing files. Call the enable/disable in the slicer's start gcode and a enabie in the end gcode.
Note: you will get homing failed errors when homing is disabled in the homing files.

In config.g:

if !exists(global.DisableHoming)
 global DisableHoming=false  ;create variable for use in homing
else
 set global.DisableHoming=false ;reset variable for use in homing

In the homeing files add at the beginning:

if global.DisableHoming
 M99

EnableHoming macro:

set global.DisableHoming=false

DisableHoming macro:

set global.DisableHoming=true

In the slicer's start gcode:

M98 P"EnableHoming"
G28                            ; home all axes
M98 P"DisableHoming"

Add M98 P"EnableHoming" in the end gocde in the slicer

This finally works.
Lights up 4 red leds when above 40C, green <=40
Bed and T0 heater are set to 4 leds each.

Make sure each if and elif M150 conmmend has a beginning space

; dameon.g
; Adafruit #1426 8 led neopixel
G4 P500 ; 500ms delay
if heat.heaters[0].current > 40     ; temp
 M150 R255 P10 S4 F1     ; set first 4 red
elif heat.heaters[0].current <= 40
 M150 U255 P10 S4 F1     ; set first 4 green
if  heat.heaters[1].current > 40    ; temp
 M150 R255 P10 S4 F0     ; set second 4 red, and done
elif heat.heaters[1].current <= 40
 M150 U255 P10 S4 F0     ; set second 4 green and done

This is in my config.g to make sure the NEOPixels are off

M150 R0 U0 B0 P5 S8 F0                                   ; shut off neopixel

@westech Increasing the Z offset gets it closer to the bed, decreasing is farther away. I added this as a comment the the G31, so I wouldn't forget.

Go to System and use the "upload system files button" in DWC2.

@uca I dont't one. One way is when you home one, make sure the other isn't triggered. For example: in the homeall.g file: home x, move x away from the endstop so it's not triggered, home z. Just put a move away form the endstop for one, to use the other. You may have to connect them to both endstop connectors until the firmware can freely assign endstops.

@tomw When using a Raspberry PI. all updates must be doen with sudo apt update and sudp apt upgrade. To use the current beta version switch to unstable. I use PuTTY to acces the PI.
https://duet3d.dozuki.com/Wiki/Getting_Started_With_Duet_3#Section_Software_Installation

@TLAS For number 4. You could use this https://www.amazon.com/gp/product/B01HU7BX42 on the supplied wire connector.

@Roy Remove the bang, !, in front of the zprobe.in the M558.

@peirof Change the io7 in M558&M950 to the connections you have, io2.

@fcwilt M83 is for relative extruder mode.

@SANJR Yes they can. You'll have test them to see what the minimum speed you can run them at. For some you have run them at max speed for a second before you can run them at a low speed.

@Proschi78 I used to show if the hotend and bed is above 40C in daemon.g. I use a 8 led adafruit neopixel.

; dameon.g
while global.RunDaemon ; set to true in config.g
	G4 P500 ; 500ms delay
	if heat.heaters[1].current > 40 ; temp
		M150 R255 P10 S4 F1 ; set right 4 red, and done
	elif heat.heaters[1].current <= 40
		M150 U255 P10 S4 F1 ; set right 4 green and done
	if heat.heaters[0].current > 40 ; temp
		M150 R255 P10 S4 F0 ; set left 4 red
	elif heat.heaters[0].current <= 40
		M150 U255 P10 S4 F0 ; set left 4 green

@moth4017 I inclose mine within a while loop:
Set global.RunDaemon to true in config.g.

In deamon.g:
while global.RunDaemon
; stuff goes here

I have macros to set while RunDaemon true or false (on/off)

It's better than the rename method, since my keyboard likes to misspell words.

@cthulhulabs I use these on my 5vdc power supply: https://www.amazon.com/gp/product/B081JGZK14 and a usb cable to the PI.

@cthulhulabs With the 6HC off, the Pi will try multiple times to connect to the Duet.

@gabi68 Do you have the correct Z offset in your G31?

@tinchus To make sure the printer is homed. I also have this in start.g, so it shouldn't run in G32 during a print, but the G28 Z is in there, since the bed is heated up before running G32 and G29/mesh.g for a print. It also allows testing of the G32 without additional steps.

@tinchus Make sure you home Z before leveling, that should get rid of the warning about the Z offset.

Here's my bed.g:

; bed.g
; called to perform automatic bed compensation via G32
M561						; clear any bed transform
while iterations < #move.axes & move.axes[iterations].visible
	if !move.axes[iterations].homed
		G28
		break
G28 Z						; home Z for Z0
M290 R0 S0					;  clear baby stepping
G30 P0 X10 Y150 Z-99999		; probe near a leadscrew, half way along Y axis
G30 P1 X275 Y150 Z-99999 S2	; probe near a leadscrew and calibrate 2 motors

@fusedeep On the duet, do you have a SSID/password set up for the wifi connection and does that work?

@adamfilip I use this code to check homing:

while iterations < #move.axes & move.axes[iterations].visible
	if !move.axes[iterations].homed
		G28
		break