Duet 2 and Duex5 different temperature (Toolchanger)

johonline

If I connect the same temperature sensor to the Duet 2, it shows a temperature that is 15° higher than the temperature connected to the Duex 5.

config.g

;....

M308 S1 P"e0temp" Y"thermistor" A"T0" T100000 B4725 C7.06e-8 	; Set thermistor
M950 H1 C"e0heat" T1						; Extruder 0 heater
M143 H1 S355 							; Set temperature limit for heater 1 

M308 S2 P"e1temp" Y"thermistor" A"T1" T100000 B4725 C7.06e-8 	; Set thermistor
M950 H2 C"e1heat" T2						; Extruder 0 heater
M143 H2 S355 							; Set temperature limit for heater 2

M308 S3 P"e2temp" Y"thermistor" A"T2" T100000 B4725 C7.06e-8	; Set thermistor
M950 H3 C"duex.e2heat" T3					; Extruder 0 heater
M143 H3 S355 							; Set temperature limit for heater 3 

M308 S4 P"e3temp" Y"thermistor" A"T3" T100000 B4725 C7.06e-8	; Set thermistor
M950 H4 C"duex.e3heat" T4					; Extruder 0 heater
M143 H4 S355 							; Set temperature limit for heater 4 

;......

deckingman

@johonline My best guess is that you need a different series resistor (R) value in your M308 for the Duex 5 board. The documentation states that if no R value is given, the default value will be used depending on the board. https://docs.duet3d.com/User_manual/Reference/Gcodes#m308-set-or-report-sensor-parameters

But there are two versions of the Duex5 board. Up to V0.10, the Duex 5 used a series resistor of 4700 which is the same as the Duet 2 main board. But for Duex 5 from V0.11, the series resistor is 2200. https://docs.duet3d.com/User_manual/Connecting_hardware/Temperature_connecting_thermistors_PT1000#the-m305m308-r-parameter

I guess what it comes down to is, "is the firmware clever enough to detect the board version as well as the board type"? If not, then the default value would likely be 4700 whereas if your board is V0.11 or later, it should be 2200.

It might worth adding R2200 to the M308 for the sensor(s) that is/are connected to the Duex5.

droftarts

@johonline as @deckingman said, check what version of Duex5 you are using, and RRF version.

"is the firmware clever enough to detect the board version as well as the board type"?

Yes, but only if you are using RRF 3.4 and later. See https://docs.duet3d.com/Duet3D_hardware/Duet_2_family/DueX2_and_DueX5#pcb-revision-history

Modified the series resistors of the temperature inputs to be 2k2 so they perform better with PT1000 sensors. From RRF3.4 the DueX5 version will be detected and the correct R values set in M308, for RRF 3.3 and earlier use R2200 in the M308 command.

Ian