PT100 temp questionable

  • Hey all,

    PT100 ? brand new showing 100C higher than it is at the nozzle any ideas on a smart effector 22g wire seem to be good connection at effector and screw connector on Duet daughter board ?

    Duet 3 3.0 firmware

    ; Heaters
    M308 S0 P"temp0" Y"thermistor" T100000 B4138 ; configure sensor 0 as thermistor on pin temp0
    M950 H0 C"out0" T0 ; create bed heater output on out0 and map it to sensor 0
    M143 H0 S120 ; set temperature limit for heater 0 to 120C
    M307 H0 A122.0 C513.7 D0.5 S1.00 V24.0 B0 ; disable bang-bang mode for the bed heater and set PWM limit
    M140 H0 ; map heated bed to heater 0
    M308 S1 P"spi.cs0" Y"rtd-max31865" ; configure sensor 1 as thermocouple via CS pin spi.cs0
    M950 H1 C"out1" T1 ; create nozzle heater output on out1 and map it to sensor 1
    M143 H1 S450 ; set temperature limit for heater 1 to 450C
    M307 H1 A809.1 C335.5 D3.7 S1.00 V24.0 B0 ; disable bang-bang mode for heater and set PWM limit

  • @Carlo
    I should say though a PT1000 was having the same issue as to why I changed it last night but only now upped the temp all the way to 290c to print PLA

  • administrators

    What reading do you get from the PT100 at room temperature?

  • @dc42


    Appears normal same as the bed

  • administrators

    In that case, if the indicated temperature rises smoothly as you heat up the hot end, it's likely that it is giving the correct reading for the temperature at the PT100 sensor. That won't be quite the same as the nozzle temperature, however if you are using the standard E3D hot end and you have a silicone sock over the heater block, it shouldn't be very different. OTOH if you see a sudden temperature jump then you probably have a bad connection.

  • @dc42

    I’m using the sock with the coated copper heater block and it does rise smoothly

  • administrators

    You can test the accuracy of the PT100 interface by connecting fixed resistors in place of the PT100. Search the web for "PT100 table" to find how resistance relates to temperature. For example, a 180 ohm resistor should give a reading just over 211C.

  • @dc42

    Yeah laser thermometer show 180c when at 290 DWC and has to be that Hi to print PLA
    I’ll check with a resistor but then why would the PT1000 be showing the same error as it connects to the board and the pt100 to the daughter board?

    Unless connection at the effector is iffy

  • administrators

    @Carlo said in PT100 temp questionable:

    Yeah laser thermometer show 180c when at 290 DWC and has to be that Hi to print PLA

    If you mean an IR thermometer, those are useless for measuring the temperature of a small area such as a nozzle, or even a heater block.

  • @dc42

    Thanks... so would 100 equal 0 ?

  • @Carlo
    Cheers DC
    put 100 in shows 3.9c
    put 220 in shows 324.5c bang on ish.0011100 something.
    I'm just thrown by printing that very roll of PLA at 195c on my other printer and this one previously always at 210c and it would ooze at that now having to up it to 290c and ideally it needs to be a little hotter even

  • @dc42 it was the heater block but didn't expect over 100c error tbf using the ir

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