P0 default for M106 (Fan On) does not work in RRF3.1.1



  • In RRF3.3.1, "M106 S80" does not result in turning on the part fan like it did in 2.x, but "M106 P0 S80" does. Conclusion: the default P0 is not being properly applied in RR3.1.1. Consequently, gcode code control over part cooling is not working as the slicer sends M106 Sxx to turn on the part cooling fan (with an implied P0). Here is the config:
    M950 F0 C"fan1" Q50
    M106 P0 H-1 X255
    Did I miss something?


  • Moderator

    What have you defined as the part cooling fan in your tool definition?



  • @charames Also, try adding S1 to your M106



  • @Phaedrux Ah, thanks. Your question helped me solve it. For some reason my printer manufacturer chose not to follow the recommendation in the Duet documentation whereby it is stated “our intention is that in a 3D printer with a single print head, you use the Fan0 output for the print cooling fan and the Fan1 output for the heatsink fan. This is the easiest configuration to use because it's what the firmware expects by default." Rather, they wired the part cooling fan up to Fan1 and the tool fan up to Fan0. In any case, I swapped them in the M950/M106 config commands and it works, now. The only thing that is mysterious to me is why it worked previously when I explicitly provided P0 in the M106 command.


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