Is this blower connected correctly?

[MaxGyver]

Hey all,

I would like to ask your kind help to triple check my wiring.

I am using a Duet 6HC main board. VCC and GND of the blower are connected directly to the power supply outputs. For the control signals I would like to use the OUT6 pins.

Since VCC and GND are connected to the power supply I recon the blowers' "tachometer output" (green) goes to "out6.tach and "set speed input" goes to "out6" (PWM V-Fan)?

[Phaedrux]

Have you seen this?

https://duet3d.dozuki.com/Wiki/Connecting_and_configuring_fans#Section_Connecting_3_or_4_wire_fans

@maxgyver said in Is this blower connected correctly?:

Since VCC and GND are connected to the power supply I recon the blowers' "tachometer output" (green) goes to "out6.tach and "set speed input" goes to "out6" (PWM V-Fan)?

Sounds reasonable.

[o_lampe]

@maxgyver
let's hope the speed input allows a PWM signal. Maybe have to use a higher 'Q' value in the fan definition (M950)

[MaxGyver]

@phaedrux
Yep, works! Thank you very much for confirming.

@o_lampe
I have set the PWM-Frequency to 6000Hz. The default 500Hz where indeed to low.

How do I configure the tacho readout? For RRF.3.3 /Duet 3 ? I did not find it in the documentation or in the Forum.

[dc42]

@maxgyver how have you configured the fan in the M950 command in config.g?

The usual PWM frequency for fans with a separate speed control input is 25000.

[MaxGyver]

@dc42
Like this:

M950 F0 C"!out6" C"Blower" Q6000		; create fan 0 on pin out6 and set its frequency
M106 P0 S1 B0 L0.5 X0.8 H1:2 T80	; set fan 0 value. Thermostatic control is turned on

[dc42]

@maxgyver use C"!out6+out6.tach" in the M950 command.

[MaxGyver]

@dc42

Thanks! But for the blower, this does not work. According to the data sheet that I have posted above, it creates 3 pulses per revolution. When the blower is starting, the PWM reading jumps to around 40,000 RPM and immediately to zero. The configuration works for my other 4 Wire blower. Here the correct RPM is displayed in the UI.

[dc42]

@maxgyver what RPM is the blower supposed to achieve? Do you get a rpm reading from it if you use lower PWM?

[MaxGyver]

@dc42 the max. RPM of the blower is 39500 RPM. I am running the blower at half power, so I recon the RPM are around 15.000. While running the blower at the lowest possible speed, I do not get a reading as well. According to the data sheet, the tachometer output has 3 pulses per revolution. So for 15,000 RPM this should be 750 Hz?