Can you not use a custom thermistor for a temperature_fan?

General Discussion
1

I get Unknown temperature sensor 'CMFB103F3950FANT' for the following config.

[temperature_fan exhaust_fan]
pin: PD14
sensor_type: CMFB103F3950FANT
sensor_pin: PF5
min_temp: 0
max_temp: 100
control: watermark

[thermistor CMFB103F3950FANT]
temperature1: 0.0
resistance1: 32116.0
temperature2: 40.0
resistance2: 5309.0
temperature3: 80.0
resistance3: 1228.0

But I can use it just as a temp sensor without error.

[temperature_sensor chamber]
## Chamber Temperature - T1
sensor_type: CMFB103F3950FANT
sensor_pin: PF5
min_temp: 0
max_temp: 100
gcode_id: chamber_th

I obviously comment out that when I try to use temperature_fan so I am not using the pin twice.
https://www.klipper3d.org/Config_Reference.html#thermistor

2

The order of definitions in the config is important. You need to define the thermistor before you use it elsewhere in the config. Simply moving the thermistor above the temperature_fan should fix it.

1 Like
3

That did the trick. Documentation should probably remind users of this in the custom thermistor section.

4

It’s already there:

“Be sure to place the thermistor section in the config file above its first use in a heater section.”

5

Ah, I see my thought process. It says “heater section” and I am using it in the fan section and I didn’t put two and two together. Then I guess it should be changed to something like…

“Be sure to place the thermistor section in the config file above its first reference as a sensor type or it won’t be recognized as a known sensor.”

… for idiots like myself. :upside_down_face: