Is it possible to control a fan by a thermistor not a heater?



  • Hello,
    Just as the title reads.
    Is it possible to have a Thermostatic controlled fan triggered by a thermistor and not a heater.
    I have a thermistor reading the temperature in the 3D printer that is enclosed by 3 walls a door and bottom but the top is open, yet the temperature with the door closed can get to warm for printing PLA. So I wanted to install an exhaust fan triggered by the chamber temperature which has no heater. From what I been reading the Thermostatic controlled fan is associated by a heater or did I read that wrong.

    /quadcells



  • @Quadcells said in Is it possible to control a fan by a thermistor not a heater?:

    Hello,
    Just as the title reads.
    Is it possible to have a Thermostatic controlled fan triggered by a thermistor and not a heater.
    I have a thermistor reading the temperature in the 3D printer that is enclosed by 3 walls a door and bottom but the top is open, yet the temperature with the door closed can get to warm for printing PLA. So I wanted to install an exhaust fan triggered by the chamber temperature which has no heater. From what I been reading the Thermostatic controlled fan is associated by a heater or did I read that wrong.

    /quadcells

    Quick answer is yes. Longer answer is that depending on your firmware version, you might need to create a virtual heater, first. https://duet3d.dozuki.com/Wiki/Gcode#Section_M305_Set_temperature_sensor_parameters

    or https://duet3d.dozuki.com/Wiki/Gcode#Section_M308_Set_or_report_sensor_parameters

    and https://duet3d.dozuki.com/Wiki/Gcode#Section_M106_Fan_On



  • Thank you for you reply.

    If I have this already in my code and works:

    M305 P2 S"Chamber Temp" T100000 B3950 R4700 H0 L0 ; Chamber Temperature sensor connected to Duex5 board

    M305 P101 X1001 S"Duet Drivers"
    M305 P102 X1002 S"Duex5 Drivers"

    M305 P103 X405 T22 S"Filament DryBox Temperature"
    M305 P104 X455 T22 S"Filament DryBox Humidity [%]"

    By adding this work as a virtual heater?

    M305 P105 X103

    then control the fan:

    M106 P3 S1 T35 H103 ; Chamber fans



  • @Quadcells Yes, I think that should work.



  • @deckingman thank you. As soon as I get a chance to implement this and works I will report back and mark as solved.
    /quadcells



  • Under 'Sensors' I see "Chamber Temperature" but the reading is 2000.0 C which usually means that the thermistor is not connected. I confirmed that the thermistor works.
    this is what I have:

    ; Heaters and thermistors
    M307 H0 A215.7 C711.5 D0.8 S1.00 B0
    M307 H1 A270.7 C90.4 D6.7 B0 S1.0 ; Kraegars Heater 1. You should set the model parameters by auto tuning (using M303) for your setup.
    M307 H2 A270.7 C90.4 D6.7 B0 S1.0 ; Kraegars Heater 2. You should set the model parameters by auto tuning (using M303) for your setup.
    M143 H0 S120 ; Set temperature limit for heater 0 to 120C
    M143 H1 S280 ; Set temperature limit for heater 1 to 280C
    M143 H2 S280 ; Set temperature limit for heater 2 to 280C
    M305 P0 S"Bed" T100000 B3950 R4700 H0 L0 ; BOM thermistor values. Put your own H and/or L values here to set the bed thermistor ADC correction
    M305 P1 S"E0" T100000 B4725 C7.06e-8 R4700 H0 L0 ; E3D Semitec 104GT2 thermistor values. Put your own H and/or L values here to set the first nozzle thermistor ADC correction
    M305 P2 S"E1" T100000 B4725 C7.06e-8 R4700 H0 L0 ; E3D Semitec 104GT2 thermistor values. Put your own H and/or L values here to set the first nozzle thermistor ADC correction
    M305 P101 X1001 S"Duet Drivers"
    M305 P102 X1002 S"Duex5 Drivers"

    M305 P105 X103 T100000 B4725 C7.06e-8 R4700 H0 L0 S"Chamber Temperature"

    M305 P103 X405 T22 S"Filament DryBox Temperature"
    M305 P104 X455 T22 S"Filament DryBox Humidity [%]"


  • administrators

    @Quadcells said in Is it possible to control a fan by a thermistor not a heater?:

    M305 P105 X103 T100000 B4725 C7.06e-8 R4700 H0 L0 S"Chamber Temperature"

    If it's a thermistor then X103 is wrong in that command. Look up M305 in the GCodes wiki page.



  • @dc42
    The 'Chamber Temperature' thermistor is connected to E2 of the Duex5 board.
    Sorry I miss read the wiki page.
    Does this look correct?
    M305 P105 X2 T100000 B4725 C7.06e-8 R4700 H0 L0 S"Chamber Temperature"
    If so I'll try this when I get back to my printer later today.


  • administrators

    @Quadcells, I think you want P103 for the E2 thermistor, not P105.



  • @dc42 but P103 is used with x405 and P104 used with x455. Should I change X405 and X455 to go with P104 and P105?



  • This is what I did and it all works. Thank you for the help.

    M305 P103 X3 T100000 B4725 C7.06e-8 R4700 H0 L0 S"Chamber Temperature"

    M305 P104 X405 T22 S"Filament DryBox Temperature"
    M305 P105 X455 T22 S"Filament DryBox Humidity [%]"



  • so the sensor works now and I can read the Chamber Temp in DWC but when the temp reaches 35 C (that's what I set it for) the fans do not turn on.
    I must of missed something.

    M305 P103 X3 T100000 B4725 C7.06e-8 R4700 H0 L0 S"Chamber Temperature"
    M106 P3 S1 I0 T35 H3



  • Ok I figured it out.
    below is part of my gcode with the last bold to show where my error was, I had M106 H3 and should of been H103.
    Now it all works as it should.

    M305 P0 S"Bed" T100000 B3950 R4700 H0 L0 ; BOM thermistor values. Put your own H and/or L values here to set the bed thermistor ADC correction
    M305 P1 S"E0" T100000 B4725 C7.06e-8 R4700 H0 L0 ; E3D Semitec 104GT2 thermistor values. Put your own H and/or L values here to set the first nozzle thermistor ADC correction
    M305 P2 S"E1" T100000 B4725 C7.06e-8 R4700 H0 L0 ; E3D Semitec 104GT2 thermistor values. Put your own H and/or L values here to set the first nozzle thermistor ADC correction

    M305 P101 X1001 S"Duet Drivers"
    M305 P102 X1002 S"Duex5 Drivers"

    M305 P103 X3 T100000 B4725 C7.06e-8 R4700 H0 L0 S"Chamber Temperature" ; Chamber Temperature sensor connected to Duex5 board

    M305 P104 X405 T22 S"Filament DryBox Temperature"
    M305 P105 X455 T22 S"Filament DryBox Humidity [%]"

    M106 P3 S1 I0 T25 H103 ; Chamber fans 0.24amps 12v.


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