Duet2 Wifi & Always On (+24V) & exp.heater(?) (gnd)
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HERE'S the document describing how to connect and control fans.
HERE'S the M106 description.
The gcode command to set the fan speed is M106 Pnn Svv where nn is the fan number (default 0 if the P parameter is not present) and vv is the required speed. The speed can be expressed either in the range 0 to 1, or in the range 0 to 255. A value of 1 or less will be assumed to be in the range 0 to 1. A value of 0 corresponds to off, and a value of 1 or 255 corresponds to full speed.So, it seems like you're configuring things correctly.
Maybe you need to invert your PWM?
From HERE:
M950 F2 C"!fan2+^pb6" ; Fan 2 uses the Fan2 output, but we are using a PWM fan so the output needs to be inverted ... -
@alankilian Thank you for the reply. I have tried, with no luck so far. The fan is on, and there is no change at all in speed, irrelevant of what I attempt....
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@alankilian Thanx! Will try, and revert back!
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@alankilian Nope, no joy.
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The only thing else I can think of is to check your wiring and make sure you are connected to the signal you think you are.
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@alankilian Did double check. Not the issue...
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@Reefwarrior said in Duet2 Wifi & Always On (+24V) & exp.heater(?) (gnd):
Now I would like to use the PWM signal from one of the expansion headers (eg. exp.heater3 or exp.heater6).
is this a 4 wire fan or a mosfet module? not sure how much current the pwm signal would need but the duet is offering around 2mA
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@bearer It's a normal 2 wire fan - one red; one black wire. 24V, 0.04A
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Can't run that off the expansion port pins without a mosfet module or something else to drive the fan. (0.04A is (much) more than 0.002A)
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Alternatively, will it work if I just add a resistor between the fan and the ground terminal? I have another fan connected on one of the PWM pins (Fan02); and it is much more quiet than this fan on the 'always on'. I have swapped out fans, and it is definitely not the fan itself.
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@bearer Thanx didn't know. Any other suggestions then?
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The only other buffered pin is the z probe modulate thing, but iirc the 74125 is only good for +-20mA so nowhere near enough.
You need some sort of external components like a mosfet or anything else that can drive the fan from the 2mA available from the expansion port.
(edit: Or possibly look into how much current you need to to drive the PWM signal for a 4-wire fan, the whole point of the 4-wire fan is to control the fan speed with a small signal, but how small idk)
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you can run the fan off the second heater port.
edit nevermind its in use i see.
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@bearer Thanx!
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it says signal range 3.3v so if that is true it will work; if not for the real possibility that your order is shipped with a different mosfet than the one I've got here I'd test it and report back.
(edit: it says dual mosfet, but it can only control one fan btw - it just mean there are two mosfet in parallel to control large loads)
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@Reefwarrior said in Duet2 Wifi & Always On (+24V) & exp.heater(?) (gnd):
Can I connect the + of the fan to the + of the always on, and the - to the exp.heater6?
No, that will probably damage the processor. You would be applying 24V through the fan to a pin that is tolerant of about 3.8V max. You need to use an external mosfet driven from the exp.heater6 to switch the fan.
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Thank you for the help! Working like a charm!
