thermistor reading too low.



  • I upgraded to a Duet3 from a Duet2 running RRF3. Everything was working as it should with the Duet2. Since the replacement of the board however, I'm having a odd issue with my thermisistor's. They are reading 15 degrees too low. Right now they should be reading 20 degree's which is the temp in my shop. They are instead reading 5.4 degree's.

    M308 S0 P"temp0" Y"thermistor" T100000 B4138 R4700  A"Bed"; bed thermistor V3
    M308 S1 P"temp1" Y"thermistor" T100000 B4138 R4700   A"Hotend"; e0 temp sensor V3
    M308 S2 P"mcu-temp" Y"mcu-temp" A"Duet"
    M308 S3 P"drivers" Y"drivers" A"Drivers"
    M950 H0 C"out0" T0 ; heater 0 uses the bed_heat pin, sensor 0
    M950 H1 C"out1" T1 ; heater 1 uses the e0_heat pin and sensor 1
    
    M140 H0																		  ; Enable bed heater
    M143 H0 S120                                                                  ; Set temperature limit for heater 0 to 120C
    M143 H1 S340                                                                  ; Set temperature limit for heater 1 to 300C
    
    ; RRF V3
    M307 H0 A46.4 C211.7 D14.8 S1.00 V24.6 B0 ; bed V3
    M307 H1 A230.7 C115.6 D4.9 S0.90 V23.9 B0  ;; V3 e3d 24v hotend
    
    
    

    If I change the R value to about 2200 or so, I can get the temp in range. Same with playing with the H value. This is not ideal however.



  • @Colten said in thermistor reading too low.:

    If I change the R value to about 2200 or so,

    just remove the R parameter, and it will default to the correct value for the board, which i do believe is 2200.



  • perfect. that fixed it. I believe the duet2 uses 4700 as the default. I believe this should be documented somewhere, but I was unable to find it.



  • @Colten said in thermistor reading too low.:

    I believe this should be documented somewhere, but I was unable to find it.

    it is, or was refrenced in the old M305 command, but not the new M308 command.



  • @bearer said in thermistor reading too low.:

    but not the new M308 command.

    probably something @Phaedrux will sprinkle some magic dust on?


  • Moderator

    @bearer consider it sprinkled.


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