Redundant thermistors?



  • Hi,

    After an unpleasant thermal runaway experience where an ATMEGA had a defect that made it keep sensing room temperature while continuously heating the bed (500W),
    I thought that I want to add a 2nd redundant bed temperature sensor.

    What is the recommend way to do that in RRF3.1.1?

    Thanks
    Michael



  • on the duet that does not happen.

    if the temperature does not rise fast enough, the duet stops.

    however as a safety feature, you could add a thermal fuse.
    https://de.aliexpress.com/item/32885492280.html


  • administrators

    You can set up multiple heater protection items for a heater, see M143. Before you can use it you must set up an extra sensor with M950 and M308.

    As Veti already said RRF stops heating if the temperature doesn't rise at a given rate or if the thermistor is disconnected.



  • @mh You can add second thermistor and use it to set max temperature monitor, which will shut down the heater if exceeded. However it will not be used for normal temperature regulation. Also can switch printer off in such case by PS_ON signal if You have PSU with remote on/off control.



  • Thank you for all the suggestions!
    And yes, I will add a thermal fuse as well.


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