Using PWM fan on Duet3



  • Hello,

    I can't make my PWM fan work properly. I have an up to date Duet 3 and I plugged the 4 pin connector of a NF-A4x10 PWM Noctua fan directly on OUT_4.

    Here is the configuration I used for this fan:

    M950 F0 C"!out4" Q25000  ; create fan 0 on pin !out4 and set its frequency
    M106 P0 S0 H-1           ; set fan 0 value. Thermostatic control is turned off
    

    On DWC if I set the FAN0's speed to 5% the fan starts for 1 second and then stops. If I increase the speed the fan won't start until I reach 100%. At 100% the fan spin but at a speed way slower than it's full speed.

    I tried to change the frequency but the result is always the same.

    Wasn't I supposed to plug the fan directly on OUT_4? Or did I missed something in the configuration?

    Thanks


  • Moderator

    @Lucas said in Using PWM fan on Duet3:

    I tried to change the frequency but the result is always the same.

    What frequency have you tried?

    The Noctua is a 12v fan, are you configured to supply 12v?



  • Thank you for your reply!
    I tried multiple frequency values between 500Hz to 40000Hz all with a similar result. And I checked the voltage, it's ok.
    I figured out that If I start the fan at 100% and reduce the speed I can go down to 30% and then the fan stops.

    I tried to plug only the red and black cable of the fan to 12V and it doesn't seems to spin faster than in PWM mode at 100%. Maybe the Noctua fan is just too slow for my needs.

    Does anyone use this fan as a part cooling fan with good results?



  • @Lucas said in Using PWM fan on Duet3:

    Maybe the Noctua fan is just too slow for my needs.

    if its a 4-pin fan it will have a tachometer output the Duet can read the RPM and you can compare to the specs of the fan. Likely its just too slow, its the trade off for low noise.

    if you used io4 change M950 F2 C"!io4.out" to M950 F2 C"!io4.out+^io4.in" f.ex.
    (correct for typos as needed)



  • Thanks, I'll try to read the tachometer value to see if it matches the specs



  • @bearer Hello, I managed to get the fan speed with this command: M950 F0 C"!out4+out4.tach"
    The value reported by DWC is around 4670 RPM which corresponds to the (+/- 10%) 5000 RPM announced in the specs.
    So this Noctua seems to be too slow for my needs, I'll change the design of my printer to use a PWM radial fan instead.

    Anyway, thanks @bearer & @Phaedrux for your help.

    Have a nice day,


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