One heater using 2 outputs?

  • I have a chamber heater that has 2 sections - 24V 5A each. I am using Duet3 and I would like to configure it so the out2 and out3 drive each section, but I always end up with only one output working.

    Is there any way to define single chamber heater, that uses 2 outputs in parallel in RRF 3.1.1?
    Or map 2 heaters as a chamber heaters...

    And yes, I know that I can use external mosfet, but I am trying no to.

  • administrators

    You can define multiple chamber heaters, e.g. M141 P0 H2 for the first and M141 P1 H3 for the second. However, if they both heat the same area then the PIDs may fight with each other if you don't get the settings just right.

    Are you using the bed heater output already?

  • Two chamber heaters might, and probably will, cause PID related issues.

    I am using bed heater output, just as intended - for bed heater, but I have to measure the current it takes. Perhaps it is possible to move it to out2/3.
    EDIT: it takes about 10A, so no go for out2/3 for bed heater.

    I tried something like M950 H2 C"out2+out3", but only one output works. Also M141 H2:3 is not a way to go.

  • @dc42 What if I use on/off instead of PID? Should this skip the PID issues ?

  • administrators

    I would use PID. If you use exactly the same PID constants for both and don't have the I term set too high then they should stay in step. But you can use bang-bang if you prefer.

  • @dc42 I will try solution with 2 heaters defined.

    But in general there is no way to define one heater using more than one outputs, and mosfet appears to be the only solution to make it less workaround-ish.

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