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

dc42

@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.

Quadcells

@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.

dc42

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

Quadcells

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

Quadcells

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 [%]"

Quadcells

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

Quadcells

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.

Tinchus

@dc42 I post here since it is the same question but for reprap 3.3 and duet3 board:

Im trying to make work a fan with a thermistor but I think I dont know all details about virtual heaters. Reading the docs on reprap 3.3 virtual heater are not needed anymore in order to use a temp sensor. It is a fan that I want to turn on when the temp on the electronics case reaches certain temperature

I Im using this codes:

M308 S5 P"temp3" Y"thermistor" T100000 B4138 A"electronics chamber" : I create the sensor
M950 F2 C"out4" T5 ; create the fan and map it to use sensor5
M106 P2 S50 T40 H2 ; I turn on the fan 2 created before, at a low speed of 50, to be triggered at t atemp of 40 degrees by "heater"2 (sensor 2)

This last line is not working. The M950 ceated the fan and till that point I can turn on and off the fan manually with DWC or using a M106 P2 SXXX.
But the triggered by temperature seems to no be working. I can read on the screen a temp of 32 degrees on the sensor, but as soon as I execute M106 P2 S50 T40 H2, the fan starts working. Since the temperature is 32, it shouldnt

What Im doing wrong?

And I have a question: the M106 will make the fan to stop when temperature is below the trigger value T?

Thanks in advance

T3P3Tony

@tinchus this is what I did on my setup and it appears to be working as expected:

M308 S5 P"temp3" Y"thermistor" T100000 B4138 A"electronics chamber"
M950 F10 C"out8" T5
M106 P10 T40:50 H5

Try changing your M106 to the following:
M106 P2 T40 H5

As its thermostatic you don't use the "S" parameter to control the speed. Its controlled by the temperature of the sensor. In your case 0ff under 40C, on over 40C. In my example I have a ramp from 40 to 60C, fully off under 40, fully on over 60.

If you want to limit the max speed of the fan the use the "X" parameter in your M106 line like this:

M106 P2 X50 T40 H5

See the documentation for more info.
https://duet3d.dozuki.com/Wiki/M106

Tinchus

@t3p3tony thanks for the extra info. I found my error:

I was using M106 P2 S50 T40 H2, The H2 was wrong, since my sensor was number 5.
I changed that before reading your message and it works. I will add the temperature range, but I have to say that using the S parameter to control the speed works too despite it is a thermostatic fan.