Duet-Wifi Fans won't turn off

kraegar · 4 Nov 2016, 16:37

Ah, nice, that's even easier. Thanks!

elmoret · 4 Nov 2016, 20:12

So I got this: https://amzn.com/B01J78FX9S

Thinking I could connect it to 12v in, and run the 12v out to the motor, and connect the fan control to the signal / ground on it.

Unfortunately, it's always on when connected that way. Anyone know if I can use a PWM controller like this to accomplish what I'm trying to do?

It looks like that expects the PWM on the high side, not the low side. The Duet switches the low side.

I think you could attach a ~10k resistor between the fan terminals, run - from the fan to the + input of the board you bought and - from the power supply to the - input of the board you bought, but I'd have dc42 confirm that before proceeding.

You'd also need to invert the PWM signal in firmware/g-code if you do that.

kraegar · 4 Nov 2016, 20:56

Yeah, I ordered a different board. I have a workable solution in place for now.

Qdeathstar · 26 Nov 2016, 14:36

Sadly, I too have lost the ablitty to turn off P0 because of the berdAir fan….. Worked fine on the RAMBO board i was using, but not on the duet. I know DC42 said that fan mapping is supported using "F parameter" on the M563 command, so would it be something like:

;M563 P0 D0 H1 //default setting, P0 mosfet damaged, so:
M563 P2 D0 H1 //use P2 output instead

now, Heater one is using fan 2 as the part fan? And, would an SSR be an appropriate way to drive the fan?

T3P3Tony · 26 Nov 2016, 15:16

The way to map the fan to a specific tool:

http://reprap.org/wiki/G-code#M563:_Define_or_remove_a_tool

Is with the specific "F" command.

So for tool 0 but with fan 2:

M563 P0 D0 H1 F2

Qdeathstar · 26 Nov 2016, 17:20

Oh, makes sense now…

Is there any compelling reason to fix the f0 mosfet if I'm not using than many fans?

T3P3Tony · 26 Nov 2016, 19:07

As long as it's not failed in a way that means it is getting hot or causing a short on the board that makes the board misbehave then no need.

kraegar · 29 Nov 2016, 16:01

FYI - it's crazy overkill for this use, but this is what I ended up using: http://a.co/hpcQl1r

Lets me drive the air pump with PWM, works great, and absolutely can handle the draw. A bit spendy compared to other options.

I may actually pick up another for my bed, though. Works great.

Qdeathstar · 1 Dec 2016, 00:34

I just got an SSR, workes fine. But, Mhackney posted that as a suggestion for me to use as well, but specifically recommended against using that for a heated bed, since they fail in the ON postion which might cause a fire.

He recommends this:

http://www.auberins.com/index.php?main_page=product_info&cPath=2_30&products_id=288

kraegar · 1 Dec 2016, 14:34

Interesting note, thanks.