How to connect 3 wires fan to Mini5+?

zapta

Hi all,

I have two Noctua A6x25 12V fans that I want to use to cool the electronic may of my printer. My plan is to connect them in parallel (three wires: (+), (-) and fan's PWM inputs) to connector Out3 of the Mini5+, leaving the the fans' tacho outputs stay disconnected. Fans 0, 1 are already defined so this can be fan 2.

How do I set this in config.g and how do I set the fan speed via a g-command? I looked at M950 in the documentation but was not sure how to use it.

https://noctua.at/en/nf-a6x25-pwm/specification

dc42

@zapta yes you can connect them in parallel to one of the Duet 3 Mini 4-pin OUT connectors; except connect only one of the two tacho wires. The pin ordering on the Duet connectors is the same as in your diagram. So blue goes to OUT_n_NEG, green (from one fan only) to OUT_n_TACHO, yellow to V_OUTLC1 and black to GND.

In M950 set the PWM frequency to 25kHz and invert the PWM output. Example:

M950 F2 C"!out3+out3.tach" F25000

Use M106 to set the fan speed or to control it thermostatically.

zapta

Thanks @dc42, I followed your instructions and a single 4-wires fan works as expected. Will connect the secondone in parallel once it will arrive.

A couple related questions

What difference does the tacho signal make from user perspective? Is the RPM reading visible anywhere? Is it possible to set alerts if the fan fails? Anything else?
is it reasonably possible to connect to the Mini5+ more than two 3-wires or 4-wires, independently controlled, fans? E.g. using outs 5,6 and PWM signals from other connectors (e.g. IO3 or IO4 which are currently free)

dc42

@zapta said in How to connect 3 wires fan to Mini5+?:

What difference does the tacho signal make from user perspective? Is the RPM reading visible anywhere? Is it possible to set alerts if the fan fails? Anything else?

The RPM can be viewed in DWC. It is also available on the object model, so you can write commands that depend on it.

is it reasonably possible to connect to the Mini5+ more than two 3-wires or 4-wires, independently controlled, fans? E.g. using outs 5,6 and PWM signals from other connectors (e.g. IO3 or IO4 which are currently free)

Yes you can do that. For a 3 wire fan, connect red to the VOUTLC pin and blue to the OUT- pin of the 2-pin OUT connector, and connect black to ground. If you want the tacho reading, connect yellow to a IOx.IN pin.

zapta

@dc42 said in How to connect 3 wires fan to Mini5+?:

Yes you can do that

I will give it a try. Thanks.