https://docs.duet3d.com/User_manual/Reference/Gcodes#m591-configure-filament-sensing
depending on type of filament sensor you are using things change . If its a switch, you need to know if it is normally open or closed that determines whether you have filament or you don't. if you want it to detect and pause during print.
for normally open switch
M591 P1 C"e0stop" S1 D0 ; filament sensing during print
if that didnt work just try P2
you can also setup sensor to detect filament and auto load in new firmware, which you need to make trigger file for. i suggest you get this covered first.

@nightowl999 When you use a massive ups the power doesn't drop so duet doesn't detect anything until ups is dead at that point what is the point of using ups. but ups can detect the powerloss and trigger the board on a pin.

@nightowl999 I just skimmed your thread. CNC machine is very power hungry I assume. my application is 3d printer, a small china ups is pretty massive for a BTT or MKS. i think you need a 5v ups for duet board.
the config is pretty well laid out in wiki
https://docs.duet3d.com/User_manual/Reference/Gcodes#m911-configure-auto-save-on-loss-of-power

"For Duet + SBC, a solid external 5V supply is recommended for the Duet + SBC for this feature to work. When power to the Duet + SBC is cut, the SBC may turn off before the Duet can inform the SBC about the content of resurrect.g, or the SBC may lose power while it's trying to write the content of resurrect.g to the microSD card. An external 5V buck regulator may be sufficient to keep a Duet 3 Mini 5+ and SBC on long enough. For Duet 3 MB6HC, the on-board 5V regulator might not endure long enough for resurrect.g to be written to persistent storage if the Duet powers an SBC as well. Hence we recommend using an external 5V PSU if this feature is configured. "

@nightowl999 well looks like if you have a ups module you can manage the power recovery very well even without M911. in trigger file you can pause the printer or cnc with G25 and it makes sys/resurrect.g
after that you can just recover with m916. I will write guide if it works, I think you can use it. those ups are very cheap.

@nightowl999 not really but it should be a misprint, i should actually try that.

@phaedrux v3.4.1 I think. I copy and paste them inside config, I don't like 2 config files. I'm OCD like that lol. i stumbled on M570 Im about to test some stuff.

@fcwilt thanks, so if the move is long it wont trigger on time to save the print.

@gloomyandy I put it there ill add it here too maybe it helps someone some day
m122.txt
m955 p0
Accelerometer 0 type LIS3DH with orientation 41 samples at 1344Hz with 10-bit resolution, SPI frequency 1000000

well I tried everything, I dont think this is wire issue, acclerometer is being detected but It doesn't stert recording.

"m955 p0
Accelerometer 0 type LIS3DH with orientation 41 samples at 1344Hz with 10-bit resolution, SPI frequency 2000000"

M956 P0 S1000 A0 F"4-X64-191-0-none.csv" G1 X191 F12000
Error: M956: Failed to start accelerometer data collection

in recorded file:
Sample,X,Y,Z
Failed to start accelerometer

@mandragora I appriciate you sending me this link, I need to use a usb wire for cs that is running in a separate jacket looks like. I understand what could go wrong now.

@mandragora I red I should add 1k resistor on SDO. are you sure its SDA? I do home my printer before readings , it still says: M400 M956 P0 S1000 A0 F"1-X64-191-0-none.csv" G1 X191 F12000
Error: M956: Failed to start accelerometer data collection

I have the same issue, did you find a solution? not a beta firmware though

@norder
thank you, I am trying lots of stuff, ill add that to the list.
My theory is that my sensor is faulty. I used very very short USB cable and have same result.
some people add a resistor SDO I think.

@norder ye, the setup is not for a duet board but I spoke with people on teamglumy actually gloomyandy himself, looks like the problem is the cable that I am using, a lot of people are having success with quality shielded usb cables and apparently it helps to reduce frequency. thank you for trying to help.

@norder

; Configuration file for BTT SKR 2 (firmware version 3)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.4.0-LPC-STM32+2 on Thu May 26 2022 15:28:29 GMT-0700 (Pacific Daylight Time)

; General preferences
M80 C"pson" ;PSON
G90 ; send absolute coordinates...
M83 ; ...but relative extruder moves
M550 P"Sinole3D1" ; set printer name
M575 P1 S2 B57600

; Network
M552 S1 ; enable network
M586 P0 S1 ; enable HTTP
M586 P1 S1 ; disable FTP
M586 P2 S0 ; disable Telnet
;

;Screen Setting
;M918 P1 E4 F100000 ;LCD
M575 P1 S2 B57600 ;set tft

; Drives
M569 P0 S1 D3 V4000 ; physical drive 1 goes forwards - x-axis
M569 P1 S0 D3 V4000 ; physical drive 1 goes backwards - y-axis
M569 P2 S1 D3 V40 ; physical drive 2 goes backwards - z - left
M569 P3 S1 D3 V40 ; physical drive 3 goes forwards - Extruder
M569 P4 S1 D3 V40 ; physical drive 4 goes backwards - z righ

;
M584 X0 Y1 Z2:4 E3 ; set drive mapping
M671 X-39:291 Y0:0 S1.00 ; leadscrews at left (connected to Z) and right (connected to E1) of X axis
;
M350 X16 Y16 Z16:16 E16 I1 ; configure microstepping with interpolation
M92 X100.00 Y200.00 Z400.00:400.00 E830.00 ; set steps per mm
;speed
M566 X600.00 Y600.00 Z24.00:24.00 E270.00 ; set maximum instantaneous speed changes (mm/min)
M203 X12000.00 Y12000.00 Z720.00:720.00 E7200.00 ; set maximum speeds (mm/min)
M201 X3000.00 Y3000.00 Z200.00:200.00 E1250.00 ; set accelerations (mm/s^2)
M204 P3000.0 T3000.0 ; set print and travel accelerations (mm(s^2)
;M201 X500.00 Y500.00 Z100.00 E500.00 ; set accelerations (mm/s^2)
;M203 X12000.00 Y12000.00 Z1200.00:1200.00 E7200.00 ; set maximum speeds (mm/min)
;M204 P500.0 T500.0 ; set print and travel accelerations (mm(s^2)
;M566 X600.00 Y600.00 Z48.00 E270.00 ; set maximum instantaneous speed changes (mm/min)
;
M906 X1200 Y1700 Z400:400 E800 I30 ; set motor currents (mA) and motor idle factor in per cent
M84 S50 ; Set idle timeout
;
; Axis Limits
M208 X0 Y-4 Z0 S1 ; set axis minima
M208 X255 Y212.5 Z210 S0 ; set axis maxima

; Endstops
M574 X1 S3 ; configure sensorless endstop for low end on X
M574 Y1 S3 ; configure sensorless endstop for low end on Y
M574 Z1 S2 ; configure Z-probe endstop for low end on Z
;M574 Z2 S3 ; configure sensorless endstop for high end on z

; Z-Probe
M558 P5 C"zstop" H1 F600 T8000 A3 S0.03 ; set z probe to super pinda
;M308 S2 P"e1temp" A"Pinda V2" Y"thermistor" T100000 B3950 ; temperature of PINDA2
;G31 H2 S30 T0.005 X23 Y5 Z0.5 ; set Z probe trigger value, offset and trigger height
;G31 P1000 H2 S30 T0.005 X23 Y5 Z0.55 ; set Z probe trigger value, offset and trigger height super pinda
;
M557 X25:250 Y5:200 S35 ; define mesh grid
M574 Z1 S2 ; set endstops controlled by prob
;
; Stallguard Sensitivy
;
M915 X S2 H200 R0 ; set X axis Sensitivity
;M915 X S2 R0
M915 Y S1 H400 R0 ; set Y axis Sensitivity
;M915 Y S1 R0
;M915 Z S0 H150 R0 ; set Z axis Sensitivity

; Heaters
M308 S0 P"bedtemp" Y"thermistor" T100000 B4092 ; configure sensor 0 as thermistor on pin bedtemp
M950 H0 C"bed" T0 ; create bed heater output on bed and map it to sensor 0
M307 H0 R0.239 K0.525:0.000 D7.19 E1.35 S1.00 B0 ; disable bang-bang mode for the bed heater and set PWM limit
;M570 H0 S60 T2
M140 H0 ; map heated bed to heater 0
M143 H0 S120 ; set temperature limit for heater 0 to 120C
M308 S1 P"e0temp" Y"thermistor" C7.060000e-8 T100000 B4725 ; configure sensor 1 as thermistor on pin e0temp
M950 H1 C"e0heat" T1 ; create nozzle heater output on e0heat and map it to sensor 1
M307 H1 R2.623 K0.287:0.000 D7.21 E1.35 S1.00 B0 V24.0 ; 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"fan0" Q500 ; create fan 0 on pin fan0 and set its frequency
M106 P0 S0 H-1 ; set fan 0 value. Thermostatic control is turned off
M950 F1 C"fan1" Q500 ; create fan 1 on pin fan1 and set its frequency
M106 P1 S0 H1 T45 ; set fan 1 value. Thermostatic control is turned on and set to 50% duty
M950 F2 C"fan2" Q500 ; create fan 2 on pin fan2 and set its frequency
M106 P2 S0 H-1 ; set fan 2 value. Thermostatic control is turned off

; Tools
M563 P0 D0 H1 F0 ; define 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
M302 S180 R180 ; allow extrusion starting from 180°C and retractions already from 180°C

; Custom settings
;
; =========================================================================================================
; other settings
; =========================================================================================================
;
M18 XY ; release / unlock x, y
M501 ; use config-override (for Thermistor Parameters and other settings)
G90 ; send absolute coordinates...
M83 ; ... but relative extruder moves
;
; =========================================================================================================
; filament handling
; =========================================================================================================
;
; execute macros that determine the status of the filament sensor
;
M98 P"0:/sys/00-Functions/FilamentsensorStatus"
;
; =========================================================================================================
;
; =========================================================================================================
;
; Offsets - place off-sets for x and y here. z-offsets are handled in the print sheet macros
;
G31 P1000 X23 Y5
;
; =========================================================================================================
;
M950 J3 C"nil"
M950 J3 C"PWRDET" ; input 1 e0 filament sensor
M581 P3 T3 S0 R1 ; PLR sensor P1 triggers Trigger3.g always (R0) TRIGGER OFF
M669 S1 t1
; =========================================================================================================
; Neopixel LED
; =========================================================================================================
M150 X2
M150 R255 U0 B0 P255
G4 P600
M150 R0 U255 B0 P255
G4 P600
M150 R0 U0 B255 P255
G4 P600
M150 R255 U255 B255 P255
; =========================================================================================================
; accelratometer
; =========================================================================================================
M955 P0 C"E.9+E.10" I41
;M918 P1 E4 F100000 ;LCD

My printer ca detect the accelerometer
"m955 p0
Accelerometer 0 type LIS3DH with orientation 41 samples at 1344Hz with 10-bit resolution, SPI frequency 2000000"
but I every time I try to record motion , i get this error:
Error: M956: Failed to start accelerometer data collection
can anyone tell me what is going wrong?
appriciate the hlep

if I want to write a "if" function how should I address endstop swtich status. like

if {endstop.swtich[n] == 1}

it want to just do everything in pause.g and not write a trigger that addresses pause. according to gloomyandy that doesn't work great. with the "if" I can make pause.g to also turn of bed and motors when switch is triggered. and in case of normal pause just pauses.