PT100 Wiring



  • Hey guys,

    I have wired a Wanhao D6 with a Duet 2 Wifi and I am new to wiring printers. My heater power and 2-wire PT100 hot-end sensor are wired using a shielded 4-wire cable. Going through Step 3.9 of the setup guide (Configuration: Check Heater Functionality), as soon as I enable heat to the hot-end, the temp reading spikes and then faults and cuts power.

    I was following a wiring write-up from someone who went through the same upgrade, and they noticed that the PT100 signal would go off the scale whenever the extruder stepper moved. They then re-wired the PT100 with it's own dedicated shielded wire. I didn't expect this would be an issue for a heater vs a stepper, but do you think this is an interference issue that can only be solved by dedicated shielded wiring for the PT100?

    Thanks for any help!
    Matt



  • The heater is usually driven by a PWM output and as such about as noisy as a stepper driver, infact more as the Trinamic stepper drivers output a fairly smooth sinusoidal signal to the motor.

    But I'd start by verifying the wiring is correct as it could be a short between the heater and the pt100.



  • @bearer ok thank you!


  • administrators

    If the temperature reading errors are caused by interference then it's possible to add capacitors to the PT100 daughterboard to suppress it, similar to the way it was done for older thermocouple daughter boards as described here https://forum.duet3d.com/topic/1270/thermocouple-issues/11. The capacitors should be connected between each of the two inner pins of the terminal block and the ground plane of the PCB.


 

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