You're right, @droftarts! I was told it was a PT100 but in reality is a 100k thermistor. Now is finally reading well! Thank you!!

@Phaedrux this helped with the Paneldue thanks!

I still have problems with the heater 1, though. It is no longer reading -273, but it returned to 2000 °C. Connecting a 100Ω resistor, it reads -1.5°C. My wiring looks ok, and I have tried different things on my config.g, but I can not get it right. My PT100 thermistor has a 108KΩ resistance at room temperature.

This is my config.g of the H1
; HotEnd
M308 S1 P"spi.cs1" Y"rtd-max31865" ; configure sensor 1 as PT100 on pin spi.cs1
M950 H1 C"e0heat" T1 ; create heater and map sensor 1
M307 H1 B0 S1.00 ; disable bang-bang mode for heater and set PWM limit
M143 H1 S295 ; set temperature limit for heater 1 to 295C

Sorry for the inconvenience, could anyone help me here? Thanks in advance!

Hello, @chrishamm and @dc42

I updated the firmware 3.4.6 version. Also updated my config.g file parameters.
But I have a couple of troubles. First, Heater 1 is still not reading correctly. It is reading -273.1 C with or without the thermistor connected. The thermistor does work, it has a 110KΩ resistance at room temperature.

; HotEnd
M308 S1 P"e0temp" Y"thermistor" T100000 B4680 C6.455513e-8
M950 H1 C"e0heat" T1
M307 H1 A216.0 C139.3 D1.0 S0.57 V24.3 B0 ; Disable bang-bang for heater and set PWM limit
M143 H1 S300 ; Set temp limit for heater 1

2nd problem: The interface is no longer reading anything, is a PanelDue 7i. It turns on as always but won't send a command to the printer, nor read temperatures or coordinates.

I appreciate the help!

Hello everyone,

I have problems with the PT100 from my Heater 1. It has been reading 2000°C and I have tried some of the previous solutions in this forum but with no success yet.

I am using a Duet 2 WiFi/Ethernet board and a RRF version 2.03. Also using the TP100 daughterboard. I used the 100Ω resistance on the TP100 cables and is giving me -1.5 (close to 0, which I think is good). I tried with two different PT100 thermistors, a 300°C one and a 500°C one with the respective config.g changes, but couldn't get it. The 300°C resistance reads 103KΩ and the 500 reds 4MΩ (so I think both work).

These are my 300°C lines:

; Heaters
M307 H0 B0 S1.00 ; Disable bang-bang mode for the bed heater and set PWM limit
M305 P0 T100000 B4138 C0 R4700 ; Set thermistor + ADC parameters for heater 0
M143 H0 S115 ; Set temperature limit for heater 0 to 110C
M305 P1 X200 S0.55 ; PT100 Chanel 1
M143 H1 S295 ; Set temp limit for heater 1
M570 H1 P20 T25 ; Adjust heater parameters - 10-second threshold over 25C

500°C lines:

; Heaters
M307 H0 B0 S1.00
M305 P0 T100000 B4138 C0 R4700
M143 H0 S115
M305 P1 R4700 H0 L0
M305 P1 T4606017 B5848 C5.548428e-8 R4700 H0 L0
M307 H1 A580.4 C256.6 D6.4 S0.50
M143 H1 S493
M570 H1 P20 T25

Can anyone help me figure it out? I really would appreciate it. Thank you!