Unsolved Duet 2 Wifi Fan Issues
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Trying to use the fan ports on a Duet 2 wifi to control a 12V electromagnet. I have the fan jumper on the VIN selection and the board is powered at 12V. However, my always-on fans (just as a check) never turn on and I can't turn on the fan0 with M42 either. I checked both sets of pins with a multimeter and didn't get much of a reading, but unsure if you can given the PWM signal (though I thought I had before). M98 on my config yields no issues either. Any help is appreciated
; General preferences G90 ; send absolute coordinates... M83 ; ...but relative extruder moves M550 P"FSR Test Bench" ; set printer name ; Network M552 S1 ; enable network M586 P0 S1 ; enable HTTP M586 P1 S0 ; disable FTP M586 P2 S0 ; disable Telnet ; Drives M569 P0 S1 ; physical drive 0 goes reverse M569 P1 S0 ; physical drive 1 goes forward M584 X0:1 ; set drive mapping M350 X16 I1 ; configure microstepping with interpolation M92 X80.0 ; set steps per mm M906 X1000 I30 ; set motor currents (mA) and motor idle factor in per cent M84 S30 ; set idle timeout ; Axis Limits M208 X0 S1 ; set axis minima M208 X267 S0 ; set axis maxima ; EndStop M574 X1 S3 ; X endstop on low end with sensorless homing M915 X R0 F0 ;Relays M950 F0 C"fan0" Q500 ;tray electromagnets M106 P0 S1 H-1 -
undefined JRCL marked this topic as a question
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my always-on fans (just as a check) never turn on
They are 'always on' as the name implies. Thus, G- or M-Codes have no effect.
I checked both sets of pins with a multimeter and didn't get much of a reading
That's weird: According to these schematics, the V_FAN pins should carry 12V (well, depending on the V FAN JUMPER SELECT jumper position and the voltage supplied to VIN). The PWM fans are different: Here, the FAN# pins are actively switched to GND, the V_FAN pins should always be at 5V or VIN - depending on the V FAN JUMPER SELECT. Check the fuse VIN to Fans MiniBlade (see schematics).
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@JRCL Check the 1A fan fuse, it may be blown. Also check you have a jumper on the 'V FAN JUMPER SELECT' pins. See the wiring diagram: https://docs.duet3d.com/duet_boards/duet_2_wifi_ethernet_maestro/duet2ndgen_connections_v1.0-1.5_d2.1.png
Are you running the electromagnet directly from the fan port (probably way too much current) or via a relay?
Ian
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@infiniteloop @droftarts It was the fan miniblade fuse! Should've checked this sooner but haven't blown many fuses yet, lesson learned. I had even swapped my Duet 2 wifi with another at a point so I thought no way both have a blown fuse....sure enough they both did. I think it was long before I was setting up this machine as the electromagnet has less than 1A draw on 12V, but I'll be double checking
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the electromagnet has less than 1A draw on 12V
How much less? The fuse can take 1A, but the MOSfets of the PWM fans are limited to 800mA IIRC, so you are possibly better off with a relay as @droftarts suggests. Anyway, you should provide a flyback diode.
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@JRCL the medium-current (i.e. fan) outputs on Duet 2 are rated 1A but can handle 1.5A for short periods e.g. when a fan is starting up. However, the entire fan power circuit (2 always-on output and two switched outputs) shares the fuse, which is normally 1A. You can increase it to 2A or even 3A if you are sure that the individual outputs are not overloaded.
Duet 2 boards include flyback diodes on the fan outputs but not on the heater outputs.
