PT100 extruder temp mismatch



  • I am am in the process of installing a duet3 6HC board to an AON-M1 printer. It has two independent x-carriages both with pt100 sensors in the hot ends (connected to the pt100 daughterboard mounted on the provided standoff). I just fired them up using 22awg wiring, and on the DWC I got the sensors to show up on the temperature chart. However, one reads ~33C and the other ~46C when the ambient temperature of the chamber is ~27C.

    Any advice on how I can dial it in to give an accurate measure?

    Cheers!



  • The PT100 thermistors are only useable on Duet Boards through the use of a daughterboard https://www.duet3d.com/PT100_DaughterBoard
    Each board can accept two PT100's and 2 boards can be added to each duet board.

    Missed where you mentioned daughter boards


  • administrators

    Assuming the PT100 sensors are good, it sounds like you have too much resistance in the wiring between the daughter board and the sensors. Each ohm of resistance will increase the temperature reading by about 2.5C.

    If the wires to the sensors need to be long then a 4-wire connection is best.



  • @dc42 Right on, might have to switch to 4-wire. Before doing so, I must also mention that there is I believe 2 molex connections one within the printer and one inside the board/power box for the printer. Could the molex connections be problematic?


  • Moderator

    @kroybal said in PT100 extruder temp mismatch:

    Could the molex connections be problematic?

    If it increases resistance, then yes. Going 4 wire should help resolve even that though.


  • administrators

    Yes, for the one that reads 46C I suspect there is a bad connection, possibly a bad crimp.


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