No voltage from OUT 4 or OUT 5



  • Trying to run 24v 2 wire fans for the hot end and part cooler on a Duet3. No voltage between pins 1 and 4(PWM). Voltage jumper set for v_in but no reading from either position. I expected to see the voltage change when I adjust the fan control section on the dashboard in the DWC. What am I missing, here's a copy of my config.g.

    Tia- Mike

    ;General Setup - RailCore RRF on a SBC for Duet3
    G21 ;Work in millimetres
    G90 ;Send absolute coordinates...
    M83 ;...but relative extruder moves

    ; Stepper configuration
    M569 P0 S1 D3 ;Drive 0 X / Rear
    M569 P1 S1 D3 ;Drive 1 Y / Front
    M569 P2 S0 D3 ;Drive 2 Z Front Left
    M569 P3 S0 D3 ;Drive 3 Z Rear Left
    M569 P4 S0 D3 ;Drive 4 Z Right
    M569 P5 S1 D3 ;Drive 5 Extruder

    ;Axis configuration
    M669 K1 ;corexy mode
    M584 X0 Y1 Z2:3:4 E5 ; Map X to drive 0 Y to drive 1, Z to drives 2, 3, 4, and E to drive 5

    ;Leadscrew locations
    M671 X-10:-10:333 Y22.5:277.5:150 S7.5

    M350 X16 Y16 Z16 E16 I1 ;set 16x microstepping for axes with interpolation
    M906 X1400 Y1400 Z1200 E800 I80 ;Set motor currents (mA)
    M201 X2500 Y2500 Z100 E1500 ;Accelerations (mm/s^2)
    M203 X24000 Y24000 Z900 E3600 ;Maximum speeds (mm/min)
    M566 X800 Y800 Z100 E1500 ;Maximum jerk speeds mm/minute
    M208 X290 Y290 Z280 ;set axis maxima and high homing switch positions (adjust to suit your machine)
    M208 X0 Y0 Z0 S1 ;set axis minima and low homing switch positions (adjust to make X=0 and Y=0 the edges of the bed)
    M92 X200 Y200 Z1600 E837 ;steps/mm

    ; End Stops
    M574 X1 S1 P"io1.in" ;Map the X endstop to io1.in
    M574 Y1 S1 P"io2.in" ;May the Y endstop to io2.in

    ; Thermistors
    M308 S0 P"temp0" Y"thermistor" A"bed_heat" T100000 B4240 H0 L0 ;Bed thermistor - connected to temp0
    M308 S1 P"temp1" Y"thermistor" A"e0_heat" T100000 B4725 C7.06e-8 H0 L0 ;duet3 e3d thermistor - connected to e0_heat

    ;Define Heaters
    M950 H0 C"out0" T0 ;Bed heater is on out0
    M950 H1 C"out1" T1 ;Hotend heater is on out1

    ;Define Bed
    M140 H0

    M307 H0 A90.0 C700.0 D10.0 S1.00 B1 ;Keenovo duet 3 configuration
    M307 H1 A310.1 C144.7 D2.6 S1.00 B0 ;E3D Hotend duet 3 configuration

    M570 S360 ;Hot end may be a little slow to heat up so allow it 180 seconds
    M143 S285 ;Set max hotend temperature

    ; Fans
    M950 F0 C"out5" ;Hotend fan on "out5" connector
    M106 P0 S255 H1 T50 ;enable thermostatic mode for hotend fan
    M950 F1 C"out4" ;Layer fan on "out4" connector
    M106 P1 S0 ;Layer Fan

    ; Tool definitions
    M563 P0 D0 H1 F1 ;Define tool 0
    G10 P0 S0 R0 ;Set tool 0 operating and standby temperatures

    ;BLTouch
    M558 P9 C"io7.in" H5 R1 F120 T6000 A5 S0.02 B1 ;define the bltouch input on io7.in
    M950 S0 C"io7.out" ;define the bltouch servo on io7.out
    G31 X-4 Y42 Z2.00 P25 ;set the offsets for the bltouch

    T0 ;select first hot end


  • administrators

    @Malgandalf said in No voltage from OUT 4 or OUT 5:

    Trying to run 24v 2 wire fans for the hot end and part cooler on a Duet3. No voltage between pins 1 and 4(PWM).

    That's as expected, you do not connect 2-wire fans between pins 1 and 4.



  • I was able to figure it out. the PWM breaks the ground not the hot line. I moved the ground wire one pin over and it works great.

    For future reference where could I have found this? I did not see it mentioned anywhere in the documentation that I was able to find.



  • @Malgandalf said in No voltage from OUT 4 or OUT 5:

    I was able to figure it out. the PWM breaks the ground not the hot line. I moved the ground wire one pin over and it works great.

    For future reference where could I have found this? I did not see it mentioned anywhere in the documentation that I was able to find.

    I would like the answer to this also.



  • Is this the correct wiring description for your board?

    Duet3/6HC wiring

    4-pin KK connectors with offset spigot OUT_4 thru OUT_6: these are intended for PWM-controllable fans. The connector fits a standard PC-type 4-pin PWM fan. Alternatively, a 2-pin fan may be connected between the V_OULCn pin (+ve) and the OUT_n_NEG pin (-ve). The positive supply to these connectors is the centre pin of the 3-pin jumper block labeled OUT4-OUT6_Select. A jumper in the top position will power them from the fused VIN supply. Alternatively you can connect a 3-terminal buck regulator to the 3-pin jumper block to supply the required voltage to the centre pin.
    


  • @Malgandalf said in No voltage from OUT 4 or OUT 5:

    I was able to figure it out. the PWM breaks the ground not the hot line. I moved the ground wire one pin over and it works great.

    For future reference where could I have found this? I did not see it mentioned anywhere in the documentation that I was able to find.

    Not sure I've seen it explicitly written out, but maybe you could try to explain what could change on the wiring diagram to make it clearer? Having the same name for the positive pins across each group and tagging the output pins as PWM seems clear enough to me.



  • @bearer People sometimes think of the OUTPUT pin as the one producing the positive voltage, so connecting a fan from OUTPUT to GND would make it run.

    That's not the case here, the fan needs to be connected between OUTPUT and a positive voltage source.

    That can be confusing, and a sentence in the wiring page could help some people have a better experience.


  • Moderator

    Would a better description of fan wiring and PWM switching negative side belong here?

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



  • @Phaedrux Definitely would have helped me. I read that page six times. I'm sure that for someone with more experience reading technical diagrams it's obvious but some of us hobbyists need a little more hand holding. A single line stating that the PWM signal is produced by breaking and making the ground on Pin2 would have been all I needed.
    Pin numbers at all would also be helpful for when you're asking questions FWIW.


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