Calculating average temperature using 2 pt1000 sensors

meki05

Hello.

I have a large-format COREXY printer, and due to the large bed size, I thought I'd use two PT1000 thermostats to more accurately measure the average surface temperature.

I've tried a number of methods, but haven't found a solution. I get this error:
Error in start-up file macro line 78: Unknown sensor type name "mavg".

file config.g

; Configuration file for RepRapFirmware on Duet 3 Main Board 6HC
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.5.8 on Thu Jan 09 2025 09:36:34 GMT-0800 (Pacific Standard Time)

; General
G90 ; absolute coordinates
M83 ; relative extruder moves
M550 P"Duet 3" ; set hostname

; Accessories
M575 P2 S0 B57600 ; configure PanelDue support

; Network
M552 P0.0.0.0 S1 ; configure Ethernet adapter
M586 P0 S1 ; configure HTTP

; Wait a moment for the CAN expansion boards to become available
G4 S2

; Accelerometers
M955 P121.0 I20 ; configure accelerometer on board #121

; Kinematics
M669 K1 ; configure CoreXY kinematics

M98 P"bed_average.g"

; Smart Drivers
M569 P0.0 S1 D2 ; driver 0.0 goes forwards (X axis)
M569 P0.1 S1 D2 ; driver 0.1 goes forwards (Y axis)
M569 P0.2 S1 D2 ; driver 0.2 goes forwards (Z axis)
M569 P0.3 S1 D2 ; driver 0.3 goes forwards (Z axis)
M569 P0.4 S1 D2 ; driver 0.4 goes forwards (Z axis)
M569 P0.5 S1 D2 ; driver 0.5 goes forwards (Z axis)
M569 P121.0 S1 D2 ; driver 121.0 goes forwards (extruder 0)

; Motor Idle Current Reduction
M906 I30 ; set motor current idle factor
M84 S30 ; set motor current idle timeout

; Axes
; Define positions of Z motors
M584 X0.0 Y0.1 Z0.2:0.3:0.4:0.5 ; map Z to drivers 0.2, 0.3, 0.4, 0.5
M350 X16 Y16 Z16 I1 ; configure microstepping with interpolation
M906 X2500 Y2500 Z2500 ; set axis driver currents
M92 X20 Y20 Z6400 ; configure steps per mm
M208 X0 Y0 Z0 S1 ; set minimum axis limits
M208 X1110 Y1110 Z2005 S0 ; set maximum axis limits
M566 X1200 Y1200 Z200 ; set maximum instantaneous speed changes (mm/min)
M203 X12000 Y12000 Z300 ; set maximum speeds (mm/min)
M201 X1500 Y1500 Z300 ; set accelerations (mm/s^2)
M557 X50:1060 Y50:1060 S60 ; define mesh grid for compensation

; Extruders
M584 E121.0 ; set extruder mapping
M350 E16 I1 ; configure microstepping with interpolation
M906 E800 I30; set extruder driver current
M92 E420 ; configure steps per mm
M566 E120 ; set maximum instantaneous speed changes (mm/min)
M203 E3600 ; set maximum speeds (mm/min)
M201 E250 ; set accelerations (mm/s^2)

; Probes
M558 K0 P9 C"^121.io0.in" H5 F120 T6000 A5 S0.02 ; configure BLTouch probe
G31 P500 X0 Y0 Z0.7 ; set Z probe trigger value, offset and trigger height
M950 S0 C"121.io0.out" ; create servo for BLtouch

; Endstops
M574 X1 P"121.io1.in" S1 ; configure X endstop
M574 Y1 P"io0.in" S1 ; configure Y endstop
M574 Z1 S2 ; configure Z endstop

; Sensors
M308 S1 P"121.temp0" Y"pt1000" A"Nozzle" ; configure nozzle sensor
M308 S2 P"temp0" Y"pt1000" A"Heated Bed1" ; configure bed sensor 1
M308 S3 P"temp1" Y"pt1000" A"Heated Bed2" ; configure bed sensor 2
M308 S4 Y"mavg" A"Average Bed Temp" S"1:2" ; حساب المتوسط بين الحساس S1 و S2


; Heaters
M950 H0 C"out1" T4 ; create heater 0 for bed
M140 H0 ; assign bed to heater 0
M143 H0 S140 ; configure heater monitor for heater 0
M307 H0 R2.43 D5.5 E1.35 K0.56 B1 ; configure heater model

M950 H1 C"121.out0" T1 ; create heater 1 for extruder
M143 H1 S285 ; configure heater monitor for heater 1
M307 H1 R2.43 D5.5 E1.35 K0.56 B0 ; configure heater model



; Fans
M950 F0 C"121.out1" ; create fan 0
M106 P0 C"Tool Fan" S0 B0.1 H1 T50 ; configure tool fan
M950 F1 C"121.out2" ; create fan 1
M106 P1 C"Part Fan" S0 L0 X1 B0.1 ; configure part fan

; Tools
M563 P0 S"Tool 0" D0 H1 F0 ; create tool 0
G10 P0 X0 Y0 Z0 ; set tool offsets
G10 P0 R0 S0 ; set tool temperatures

; Miscellaneous
T0 ; select tool 0
M591 D0 P1 C"121.io2.in" S1 ; custom setting

file calculate_average.g

var temp1 = sensors.analog[2].lastReading
var temp2 = sensors.analog[3].lastReading
var avgTemp = (var.temp1 + var.temp2) / 2

echo "Bed Temp Average:", var.avgTemp

M568 P0 S{var.avgTemp}

Phaedrux

@meki05 said in Calculating average temperature using 2 pt1000 sensors:

Error in start-up file macro line 78: Unknown sensor type name "mavg".

@meki05 said in Calculating average temperature using 2 pt1000 sensors:

M308 S4 Y"mavg" A"Average Bed Temp" S"1:2"

mavg is not a valid type of sensor for the Y parameter.

https://docs.duet3d.com/en/User_manual/Reference/Gcodes#m308-set-or-report-sensor-parameters

You can create the sensors independently and take the average as you are doing and use that in other calculations, but you can't feed that back into the config as another sensor itself. You'd have to use some custom logic in daemon.g to deal with that average value as needed.

dc42

@meki05 if you don't want to read those sensors independently then you could connect both in parallel to a single temperature sensor input, and set the R parameter in the M308 command to double the standard value to compensate for that. The standard value is 2200 on Duet 3 boards.