Duet3 Monitor PWM fan operation?

zemlin

I have a few printers running Duet2 boards. I have heated enclosures on an independent temperature controller.

There is one aspect of my heated enclosure setup that can cause damage in the event of a fan failure, so I'm wondering if I moved the enclosure temp control to a Duet3 board and add the fans to the PMW outputs, would it be possible to monitor the fan operation with the tach lead on 3-wire fans?

I have ceramic heaters with 12V 80mm fans blowing on them to heat the enclosure. If those fans fail, things melt from the heaters. Trying to figure out how I can shut down the heaters if those fans stop spinning. I have had two fan failures - one resulted in more melty stuff than the other. Neither was severe, but since my machines are often running unattended ... having the control board able to monitor the fan condition and make that a requirement for firing the heaters would be a great feature.

That's not the only reason I'm considering a Duet3 - the control board would be great for cutting down the mass of wires going to the print head too.

gloomyandy

@zemlin You might want to consider installing a thermal fuse of some sort to cut the fans off it things start to get too hot. Although "active systems" are great to control and monitor things, it is always good to have a simple backup system.

dc42

@zemlin if you want to vary the fan speed using PWM and also monitor its speed using the tacho, use a 4-wire fan.

Sevimuelli

@dc42 Hi, I am working on a similar issue. I have a chamber heater with a 4-wire fan. I have one temp sensor in the chamber for regulating heating and one temp sensor on the heater itself, which shuts down the heater if it exceeds 100 Degrees. I also have a thermal fuse on the heater just in case. So its already pretty safe. I would like to monitor the fan and if it stops working or goes below a certain threshold, I get a fan failure and with that a heater failure. Thus the 4-wire fan. I think this would really help safety. Is there any possibility to do so?

If not, I imagine this would be a nice addition.

dc42

@Sevimuelli if you have a reading from the fan tacho then you can use the daemon.g file to monitor it.