Fan pwm control is different between fan connectors

  • Im having a problem with my fans

    When i connect a fan to fan2 i can perfectly control it with pwm, when I plug the same fan in for example fan4, it behaves differently and usually stops at 90%

    My guess is the pwm settings are different for both connectors, but I cant find how to change these settings ?

  • administrators

    The PWM frequency of fan ports 3 to 8 is fixed, so any F parameter in the corresponding M106 command will be ignored. It sounds to me that your fan doesn't work using standard PWM frequencies, it only works at very low PWM frequencies.

  • Did the trick

    Whats the reasoning behind this ?

  • administrators

    The fan outputs on the Duet are driven directly by the microcontroller. The fan outputs on the DueX are driven by the I2C expander chip on it, which supports PWM but sadly without control of the frequency.

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