Configure Honeywell 712-U-0-12 (1kOhm) thermistor

General Discussion
1

Basic Information:

Printer Model: Custom
MCU / Printerboard: RPI3B+7inch LCD + Arduino 2560 + Ramps
log: klippy.log (7.5 MB)

Hi! :wave:

First of all, I would like to thank the developers of this project! I really like this solution!

However, I ran into a problem when setting up the Honewell 712-U-0-12 thermistor in Klipper. Namely, I can’t correct the error in mathematical calculations using my values in the config.

So what I did:
I found technical information for my thermistor (sps-siot-c15-138-ciid-50024.pdf (93.8 KB)). I created my custom thermistor block in printer.cfg:

 # Calibrate 1k Honeywell 712-U-0-12 thermistor
[thermistor my_custom_thermistor]
temperature1: 20
resistance1: 1075.96
temperature2: 160
resistance2: 1594.22
temperature3: 300
resistance3: 2088.89

After rebooting I get the error: ValueError: math domain error
Namely in:

File "/home/pi/klipper/klippy/extras/thermistor.py", line 64, in calc_adc
     ln_r = math.pow(x - y, 1./3.) - math.pow(x + y, 1./3.)

Is there any solution to this problem? :pray:

2

Yes, even a fairly simple: Do not connect a PT1000 sensor as NTC → Configuration reference - Klipper documentation

1 Like
3

Thanks for the answer. Are you suggesting that I replace the thermistor? This thermistor was included with the printer, which operated under the control of a Repetier-Host. I thought it was still possible to somehow configure it in the Klipper.

4

In the 3D printing environment, a thermistor typically is a NTC. The settings you are playing with are only applicable to these NTCs

You are trying to connect a PTC, specifically a PT1000 PTC and the settings are neither applicable nor needed.

Delete them from your config and follow the information in the link above.

5

I tried setting up the PT1000 again. With a pull-up resistor resistance of 4.7 kOhm, the sensor shows a temperature of 921 Celsius degrees :smile:, with the actual extruder temperature being about 27 degrees.

Next, I played with the resistance value of the pull-up resistor in the config (I don’t know the real value yet) and got a more or less real temperature reading. But when I turned on the heater, the temperature sensor began to show it lower and lower. Maybe somehow can invert the ADC readings using “!” sign?

It looks like you need to install an NTC thermistor…

[extruder]
step_pin: PA4
dir_pin: PA6
enable_pin: !PA2
microsteps: 16
rotation_distance: 37.172
nozzle_diameter: 0.400
filament_diameter: 1.750
heater_pin: PB4
sensor_type: PT1000
sensor_pin: PK5
pullup_resistor: 1230  # 4700 - show 921 degress
# inline_resistor: 1000
control: pid
pid_Kp: 3
pid_Ki: 0.2
pid_Kd: 10
min_temp: -273.15  # increased ranges for debugging temperature readings
max_temp: 2750  # increased ranges for debugging temperature readings
min_extrude_temp: 190
6

The decrease in temperature readings while the extruder was heating up gave me an idea - it looks like I have an NTC thermistor. Only the data in the technical documentation is different (graph for PTC). Therefore, I decided to get the temperature values from the Repetier-Host config, on which the printer was working before the upgrade to Klipper.

And it looks like I was right. I sketched out a table in Excel and built a graph from the values that were written in Configuration.h and this is what came out:

img-2023-10-30-16-50-13
img-2023-10-30-16-50-13713Ă—414 17.3 KB

There is one pair of strange values at the beginning and end. I think they are not correct.

It turns out that I can create a custom thermistor block and use these values, since judging by the graph I have an NTC thermistor?

7

Well, then your sensor is not a HEL-707-U-0-12 :man_shrugging:

In case the NTC type is unknown, I’d recommend to use Generic 3950 as sensor type

8

To add:
The values in your graph do not match to any temperature sensor I would be aware of. So, no clue what this is supposed to be.

Without knowing the sensor type, it will be quite difficult to provide further guidance.

9

Maybe these ADC values ​​will help someone to use the Honeywell 712-U-0-12 1kOhm sensor:

# Calibrate 1k Honeywell 712-U-0-12
[adc_temperature custom_sensor]
temperature1: -35
voltage1: 5
temperature2: -30
voltage2: 2.65259
temperature3: -20
voltage3: 2.59888
temperature4: -10
voltage4: 2.54883
temperature5: 0
voltage5: 2.5
temperature6: 6
voltage6: 2.45361
temperature7: 16
voltage7: 2.40845
temperature8: 26
voltage8: 2.36572
temperature9: 36
voltage9: 2.32422
temperature10: 46
voltage10: 2.28394
temperature11: 56
voltage11: 2.24609
temperature12: 66
voltage12: 2.20825
temperature13: 76
voltage13: 2.17285
temperature14: 86
voltage14: 2.13867
temperature15: 96
voltage15: 2.10571
temperature16: 106
voltage16: 2.07275
temperature17: 115
voltage17: 2.04224
temperature18: 125
voltage18: 2.01172
temperature19: 135
voltage19: 1.98242
temperature20: 145
voltage20: 1.95435
temperature21: 154
voltage21: 1.92749
temperature22: 164
voltage22: 1.90063
temperature23: 168
voltage23: 1.88843
temperature24: 173
voltage24: 1.875
temperature25: 178
voltage25: 1.86279
temperature26: 183
voltage26: 1.85059
temperature27: 188
voltage27: 1.83838
temperature28: 193
voltage28: 1.82617
temperature29: 198
voltage29: 1.81396
temperature30: 203
voltage30: 1.80298
temperature31: 208
voltage31: 1.79077
temperature32: 213
voltage32: 1.77979
temperature33: 218
voltage33: 1.7688
temperature34: 223
voltage34: 1.75781
temperature35: 228
voltage35: 1.74683
temperature36: 233
voltage36: 1.73584
temperature37: 238
voltage37: 1.72607
temperature38: 243
voltage38: 1.71509
temperature39: 247
voltage39: 1.70532
temperature40: 252
voltage40: 1.69556
temperature41: 257
voltage41: 1.68457
temperature42: 262
voltage42: 1.6748
temperature43: 267
voltage43: 1.66504
temperature44: 272
voltage44: 1.65527
temperature45: 277
voltage45: 1.64673
temperature46: 282
voltage46: 1.63696
temperature47: 287
voltage47: 1.62842
temperature48: 292
voltage48: 1.61865
temperature49: 302
voltage49: 1.60034
temperature50: 312
voltage50: 1.58325
temperature51: 322
voltage51: 1.56616
temperature52: 332
voltage52: 1.55029
temperature53: 342
voltage53: 1.53442
temperature54: 352
voltage54: 1.51855
temperature55: 362
voltage55: 1.50269
temperature56: 372
voltage56: 1.48804
temperature57: 382
voltage57: 1.47339
temperature58: 392
voltage58: 1.45874
temperature59: 402
voltage59: 1.44531
temperature60: 412
voltage60: 1.43066
temperature61: 422
voltage61: 1.41724
temperature62: 432
voltage62: 1.40503
temperature63: 442
voltage63: 1.3916
temperature64: 492
voltage64: 1.33179
10

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