I found a setting in KISSlicer, ticked a box for "Fan can do PWM" and added "P0" to the fan on command to specify the layer fan. I'll see how it goes but it seems like the right track. Thanks for the help!

I found a setting in KISSlicer, ticked a box for "Fan can do PWM" and added "P0" to the fan on command to specify the layer fan. I'll see how it goes but it seems like the right track. Thanks for the help!

Interesting, the GCode from KISSlicer just seems to send M106 then M107. I guess the slicer software needs to be configured to send a proper M106 command with parameters?

Tried that just now, it works fine. But during a print the fan doesn't run and the Duet control screen just shows a series of error messages.

It does seem to have been a mechanical issue after all, thanks

Hi,
I've just recently finished a rebuild of my printer, the major change is a 24V high pressure layer fan (BerdAir 24V). The fan takes a PWM signal from the Duet but is powered straight from the PSU. It works flawlessly from the main control but seems to be having issues when instructed by GCode (see picture), basically it won't run during an actual print. If I start it manually it runs for about one second before being stopped.

http://tinypic.com/r/30cq547/9

Any ideas on what's upsetting Duet?

Hi,
I recently updated all my firmware and immediately began getting errors from my temperature sensor. Basically it went from working perfectly to reading 2000, which could be rectified by sending M305 P1 X0, then M305 P1 X200, then M562. I found that wriggling the cables near the effector platform could induce the error.

I tried to nail down the cause: I reconfigured the sensor to be a four wire setup using twisted pair wires, then checked and replaced electrical connections, then finally replaced the PT-100 sensor. It still happens. I think it may be the result of the PT-100 cables being close to one of the other signals coming to the effector platform (hot end fan or IR height sensor) and having some signal induced in them, since I can cause the error to appear by manipulating the cable bundle near the effector (I have checked for damaged insulation and shorts). The problem there is that this happens when the printer is at standby, not just when the hotend and fan are working. I'm about to start disconnecting wires at the Duet to see if I can isolate a set of wires somehow causing interference.

Can anyone suggest to me:
1.) A good way to diagnose the cause.
2.) Why this only started happening after a firmware upgrade?

@dc42:

Are you sure the LEDs still work if you connect them to a 12V supply?

Yep, checked a couple of times, worked my way down from >8kOhm to 100Ohm, no light, but the LED array worked after, so it's not like a bunch of current got through and cooked it during my tests. I'll try again from high resistance values but using a different ground connection, maybe the hotend fan.

The hotend is working nicely as a hotend, which is the most important thing. The hotend LED array is ultimately just bling, so if things get too hard I'll put it in a box somewhere and use it for a later project.

Thanks, I'm tinkering with resistors now, but note that even <100 Ohm doesn't result in the LEDs lighting. I put a multimeter across the hotend wires and it showed ~-8V, not 24 I suppose this is something to do with the PWM on the hotend.

I'm going to try using a resistor from the hotend 24V supply and using the ground wire for the hotend fan (which I have as not using PWM), see if that works. I have other applications in my printer for the buck regulator, so nothing will be wasted.

Thanks, I'm trying to figure out the forward current for the piddly SMD LEDs on this LED module, so that I can test a resistor solution. Out of curiosity, when a hotend is being brought up to a setpoint temperature would PWM be in use, or would it just be constantly on until approaching a the setpoint then rapidly switching to maintain?

Because the regulator blew within two seconds of starting the hotend heating. Trying to develop my understanding of how this stuff works

Though now I think about it, why would rapid switching kill the buck regulator? So long as the voltage on the input side stayed within limits (0-36V for this regulator). Do they just not tolerate rapidly changing loads?