thermistor error 2000 degree

piatra

@piatra said in thermistor error 2000 degree:

Hello and many thanks in advance for your help
My ex nozzle thermistor was down and I have replaced it with a new one and now I get 2000 degree fault at its reading

I am running duet 3.4.1 firmare

Please advice and thanks

pS: and I have just replaced the thermistor, nothing else

infiniteloop

@piatra

My ex nozzle thermistor was down and I have replaced it with a new one and now I get 2000 degree fault at its reading

You have a decent short somewhere between the Duet and thermistor. Check your lines.

piatra

I have double checked, hardly to be a short
Now I am trying to figure it out if error is related with the reason that i had a pt100 before and now I have a ordinary one (not sure even the resistance. In my config.g is set for senzor pt100…
M308 S1 P"spi.cs1" Y"rtd-max31865" ; create sensor number 1 as a PT100 sensor in the first position on the Duet 2 daughter board connector
M950 H1 C"e0heat" T1 ; create nozzle heater output on e0heat and map it to sensor 1
M143 H1 S280 ; set temperature limit for heater 1 to 280C
M307 H1 B0 S1.00 ; disable bang-bang mode for heater and set PWM limit

deckingman

@piatra To expand on what @infiniteloop has said, the thermistors that we use in our printers are NTC = Negative Temperature Coefficient. Which means that as the temperature increases, the resistance decreases. So if you are seeing a very high temperature (2000) deg C, then it means that the resistance is very low = a short circuit. It's possible that the thermistor itself is faulty but the usual cause is a wiring fault. If you have a multimeter, then you could check the resistance which, for a "normal" thermistor should be 100KOhms @25 deg C.

piatra

Thanks, but if I am buying any sensor, but not pt100 and the measurements are good should I live the config file as it is? With pt100?

deckingman

@piatra said in thermistor error 2000 degree:

I have double checked, hardly to be a short
Now I am trying to figure it out if error is related with the reason that i had a pt100 before and now I have a ordinary one (not sure even the resistance. In my config.g is set for senzor pt100…
M308 S1 P"spi.cs1" Y"rtd-max31865" ; create sensor number 1 as a PT100 sensor in the first position on the Duet 2 daughter board connector
M950 H1 C"e0heat" T1 ; create nozzle heater output on e0heat and map it to sensor 1
M143 H1 S280 ; set temperature limit for heater 1 to 280C
M307 H1 B0 S1.00 ; disable bang-bang mode for heater and set PWM limit

You need to change that M308 line https://docs.duet3d.com/User_manual/Reference/Gcodes#m308-set-or-report-sensor-parameters

Also, you can't connect a thermistor to a PT100 daughter board.

Edit. This might help too https://docs.duet3d.com/en/User_manual/Connecting_hardware/Temperature_connecting_thermistors_PT1000

infiniteloop

@piatra To expand on what @deckingman has said, you need to connect the thermistor to E0_TEMP or E1_TEMP as described here. Further reading: Configuring RepRapFirmware…

piatra

Now it is clear. Many thanks all. First step is to find out what thermistor is or buy one with specs

Thanks a lot folks

infiniteloop

@piatra said in thermistor error 2000 degree:

First step is to find out what thermistor is or buy one with specs

Measured at room temperature, you should see a resistance of several kOhm up to 100 kOhm. Round that, and you have your T parameter for M308. Good luck!

piatra

Thanks for the tip