Thermostatic controlled fans not working
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Based on the Duet documentation the chips do have a temperature sensor that can be referenced in code as a temp sensor.
I've been doing that and the fans do seem to be working as expected.
Frederick
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the chips do have a temperature sensor that can be referenced in code as a temp sensor.
Thermostatic control only works with the MCU sensor (that's what you do). The stepper drivers just provide a flag to signal overheating (when it's too late to start a fan).
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True but it is still useful.
Sure it is, depending on the circumstances - which brings me back to the start of our conversation: under specific conditions, the idea to use a proxy (as per @Phaedrux' post) makes sense. BTW: in my printer, I just engage a static fan for this purpose - poor thing, it is heavily undervolted
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@Phaedrux Yes, on different boards. The reason I am trying to do this, is when I heat the chamber, I want to make sure that the electronics on the head are sufficiently cooled, more than just the Duet electronics, I also have a webcam on the head. I may try adding an if statement to the daemon.g to turn this fan on/off depending on the chamber temp if the thermostatic control is not an option.
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What firmware version are you using?
https://docs.duet3d.com/en/User_manual/RepRapFirmware/CAN_limitations
A thermostatically-controlled fan on an expansion board can only be controlled by a temperature sensor on the same expansion board.
But that should be resolved in firmware after 3.3
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@Phaedrux 3.5.4
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Can you test if a fan on the mainboard will work thermostatically with those heaters?
You may also want to test with 3.6 RC1 as it is nearing release.
https://forum.duet3d.com/topic/37591/firmware-bundle-3-6-0-release-candidate-1-available
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@Phaedrux Not easily, it's in a deployed system. The fact that it only doesn't work (runs all the time regardless of temp) when I assign it to the bed or chamber sensors seems telling though.
Edit: I did get it to work with daemon.g with an if statement, but it'd be cool if I didn't have to do that.
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undefined Phaedrux marked this topic as a question 4 Mar 2025, 19:26
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@dc42 Are you aware of any issues using chamber or bed associated sensors for thermostatically controlled fans in the latest firmware?
Thanks
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@p8blr I am not aware of any such issues. However, I note that you are trying to control a fan connected to an expansion board using a sensor on the main board. Perhaps that combination doesn't work. Can you do some more tests to find out, e.g. try moving the sensor to an expansion board?
