Controlling IO_0 on Duet 3 MB6HC

[JRCL]

My "io0.out" pin on my Duet 3 MB6HC board with 3.4.6. seems to always be set to high regardless of my M42 designation. I figure this has to do with the fact it's used for PanelDue usually, but I can't seem to figure out a way around this. My config.g is free of errors and the IO_0 is defined like so:

M950 P4 C"0.io0.out"
M42 P4 S0

and have tried inverting the S variable as well as using a leading !, but the IO pin always seems to stay high. What can I do to fix this?

[dc42]

@JRCL check that you don't have a M575 command to switch the port to serial mode in config.g.

[JRCL]

@dc42 no M575 in my config, but here is the whole thing in case

; Enable network
G4 S5													;wait for board to start
if {network.interfaces[0].type = "ethernet"}
    M552 P192.168.1.14 S1
else
    M552 S1

;General Prefrences
G90                             						; send absolute coordinates...
M83                             						; ...but relative extruder moves
M550 P"RL1 V3"                  						; set printer name
M669 K1													; switch to CoreXY mode

; Drives
M569 P0.0 S1											; X motor runs 
M569 P0.1 S0											; Y motor runs 
M569 P0.2 S1											; Z1 motor runs 
M569 P0.4 S1											; Z2 motor runs
M569 P0.5 S1											; Z3 motor runs
M569 P20.0 S0											; E moves
M569 P0.3 S0											; U motor runs
M207 S1.5 F7200 Z0.2

M584 X0.0 Y0.1 Z0.2:0.4:0.5 E20.0 U0.3    				; Set drive mapping

M350 X16 Y16 Z16 E16 U16 I1             				; configure microstepping with interpolation
M92 X80.00 Y80.00 Z400.00 E676.47059 U100       			; set steps per mm
M566 X900.00 Y900.00 Z60.00 E300 U900.00   				; set maximum instantaneous speed changes (mm/min)
M203 X6000.00 Y6000.00 Z180.00 E7200 U17000.0			; set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z20.00 E3000 U500.0   				; set accelerations (mm/s^2)
M906 X800 Y800 Z800 U3800 I30       					; set motor currents (mA) and motor idle factor in per cent
M906 E1200 I10											; extruder current and idle factor
M572 D0 S0.02											; pressure advance-to be calibrated
M84 S30                         						; Set idle timeout

; Axis Limits
M208 X0 Y0 Z-1 U0 S1                    												;set axis minima
M208 X100 Y100 Z38.45 U330 S0              												;set axis maxima
M671 X-67.2193:182.5338:182.5338 Y54.4915:-72.3045:181.2875 S2 					; position of leadscrew/bed pivot point at front left, rear middle and front right

; Endstops
M574 X1 S1 P"0.io1.in" 									; configure switch-type (e.g. microswitch) endstop for low end on X via pin io0.in
M574 Y2 S1 P"20.io2.in" 									; configure switch-type (e.g. microswitch) endstop for high end on Y via pin io1.in
M574 Z2 S1 P"0.io3.in+0.io4.in+0.io5.in"						; configure switch-type (e.g. microswitch) endstop for high end on Z
M574 U2 S1 P"0.io6.in"									; configure switch-type (e.g. microwswitch) endstop

; Z-Probe
M950 S0 C"20.io0.out"              						; create servo pin 0 for BLTouch (use IO_4/5/7 for 6HC)
M558 P9 C"20.io0.in" H5 F120 T6000 						; set Z probe type to bltouch and the dive height + speeds
G31 P500 X-19.14 Y0 Z2.555            					; set Z probe trigger value, offset and trigger height
M557 X0:80 Y12:100 P3        							; define mesh grid

; Heaters
M308 S0 P"temp0" Y"thermistor" T100000 B3950         	; configure sensor 0 as thermistor on pin temp0
M950 H0 C"0.out0" T0                                   	; create bed heater output on out0 and map it to sensor 0
M307 H0 R0.075 K0.178:0.000 D3.39 E1.35 S1.00 B0
M140 H0                                               	; map heated bed to heater 0
M308 S1 P"20.temp0" Y"thermistor" 							; configure sensor 1 as thermistor on pin temp1
M950 H1 C"20.out0" T1                                  	; create nozzle heater output on out1 and map it to sensor 1
M307 H1 R4.766 K0.817:0.135 D4.61 E1.35 S1.00 B0 V24.4 	; disable bang-bang mode for heater  and set PWM limit
M143 H1 S280                                          	; set temperature limit for heater 1 to 280C

; Fans
M950 F0 C"20.out1" Q500 								; create fan 0 on toolboard out1 and set its frequency
M106 P0 S0 H-1       									; set fan 0 value. Thermostatic control is turned off
M950 F1 C"20.out2" Q500 								; create fan 1 on toolboard out2 and set its frequency
M106 P1 S1 H1 T45    									; set fan 2 value. Thermostatic control is turned on

;Relays
M950 P2 C"0.io_7.out"									;Clamps FWD
M42 P2 S0												;Start in off position
M950 P3 C"0.io_8.out"										;Clamps REV
M42 P3 S0												;Start in off position
M950 P4 C"0.io_0.out"										;IPV DWN
M42 P4 S0												;Start in off position
M950 P5 C"0.io2.out"										;IPV UP
M42 P5 S0												;Start in off position
M950 P6 C"0.out9"										;Forming-element
M42 P6 S0												;Start in off position



;Tool Definitions
M563 P0 D0 H1 F0										; tool 0 uses extruder drive 0 and heater 1. Fan 0 and Fan 1 are mapped to tool 0
G10 P0 X0 Y0 Z0  										; set tool 0 axis offsets
G10 P0 R0 S0     										; set initial tool 0 active and standby temperatures to 0C

; Epilogue
M556 S100 X0 Y0 Z0                                 		; Put your axis compensation here
M912 P0 S0                                        		; Put your CPU temperature sensor correction here
M501                                               		; load saved parameters from non-volatile memory
M911 S10 R11 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000" 		; set voltage thresholds and actions to run on power loss
T0