pt100



  • Hey. I have a problem with my pt100 sensors.

    IMG_20200826_184515.jpg
    As shown I use 2-wire pt100 and jumper on the left and soldered them in pairs and wrapped them to the right.

    temparatur fejl 2.PNG

    As shown in the picture I get an MCU temperature that is only about 10 degrees too much but on the extruder and the bed I get the absolute zero point. And when I press the unit I get the error that can be seen in the bottom right corner of the image. I have tried and read everything I could find on Duet3D's website and have not been able to solve it, but this is also the first time I try this so it's probably me who does not understand it but I would greatly appreciate some help so I can move on.
    Here is the code I use for my heaters.

    ; Heaters
    M308 S0 P"bedtemp" Y"thermistor" T100000 B4138 ; configure sensor 0 as thermocouple via CS pin spi.cs1
    M950 H0 C"bedheat" T0 ; create bed heater output on bedheat and map it to sensor 0
    M307 H0 B0 S1.00 ; disable bang-bang mode for the bed heater and set PWM limit
    M140 H0 ; map heated bed to heater 0
    M143 H0 S120 ; set temperature limit for heater 0 to 120C
    M308 S1 P"e0temp" Y"thermistor" T100000 B4138 ; configure sensor 1 as thermocouple via CS pin spi.cs2
    M950 H1 C"e0heat" T1 ; create nozzle heater output on e0heat and map it to sensor 1
    M307 H1 B0 S1.00 ; disable bang-bang mode for heater and set PWM limit


  • Moderator

    @Bak first, you’ve got a config.g for RepRapFirmware v3, but what firmware have you actually got on the Duet? Send M115 and post the response.

    Next, if you are using RRF3, you have the temp sensors defined as thermistors, connected to the bedtemp and e0temp pins. Should be:

    M308 S0 P"spi.cs1" Y"rtd-max31865"      ; configure sensor 0 as thermocouple via CS pin spi.cs1
    M308 S1 P"spi.cs2" Y"rtd-max31865"      ; configure sensor 1 as thermocouple via CS pin spi.cs2
    

    See https://duet3d.dozuki.com/Wiki/Connecting_PT100_temperature_sensors

    Ian



  • FIRMWARE_NAME: RepRapFirmware for Duet 2 WiFi/Ethernet FIRMWARE_VERSION: 3.1.1 ELECTRONICS: Duet WiFi 1.0 or 1.01 FIRMWARE_DATE: 2020-05-19b2

    I have tried with that code but this is the result
    promblem.PNG


  • Moderator

    @Bak Please post your current config.g. At least something has changed, going from -273 to +2000! Have you had this working before, perhaps with RRF2? If so, can you post the working config.g.

    If not, are you sure they are PT100 sensors, not thermocouples? Check the resistance. You can find a resistance table for PT100 sensors here: https://www.sterlingsensors.co.uk/pt100-resistance-table

    You should have a 100 ohm test resistor, supplied with the daughterboard. Can you wire that in? It should then report around 0C.

    Ian



  • I made it work on the extruder, I could measure that there was a loose connection on that end and the other is probably completely finished. Thank you very much for the resistance table and your help. Without that I think it would have taken me a very long time before I had found the problem.


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