Reading negative temperature and N/A temp



  • Hello,
    After wiring all (duet 2 wifi v1.04) i get the following temp reading:
    image
    what whould it be? i already changed the B value from the gcode, re-wire, it doesn't change.
    Thank you



  • -273.1 is the "magic number" that indicates a totally open circuit on an input configured for a thermistor. So you have a broken wire, are plugged into the wrong input, or similar.



  • @Danal Thank you for your help; even without anything plugged i get the "magic number", what should this indicate?
    What about the n/a one?
    Thank you



  • @johny said in Reading negative temperature and N/A temp:

    even without anything plugged i get the "magic number", what should this indicate?

    that your thermistor isn't properly connected when you think its connected.



  • @johny said in Reading negative temperature and N/A temp:

    @Danal Thank you for your help; even without anything plugged i get the "magic number", what should this indicate?
    What about the n/a one?
    Thank you

    even without anything plugged i get the "magic number"

    That is exactly what it means: Open circuit; nothing plugged in.

    Not sure about the N/A



  • @johny
    What type of thermistors are you connecting and where are you connecting them?

    Please also post your config.g file



  • Hello,
    For the heat bed it is the standard thermistors from Chinese heat beds, for the hot end its the one: ATC Semitec 104GT-2/104NT-4-R025H42G (http://www.atcsemitec.co.uk/gt-2-glass-thermistors.html )

    Gcode:

    ; Heaters
    M307 H0 B0 S1.00
    M305 P0 R4700 T100000 B4267 C0.0000000706
    M143 H0 S130
    M305 P1 R4700 T100000 B4267 C0.0000000706
    M305 P2 R4700 T100000 B4725 C0.0000000706
    M143 H1 S275

    ; Fans
    M106 P0 S0 I0 F500 H-1
    M106 P1 S1 I0 F500 H1 T45
    M106 P2 S1 I0 F500 H-1

    ; Tools
    M563 P0 D0 H1 F0 ; define tool 0
    G10 P0 X0 Y0 Z0 ; set tool 0 axis offsets
    G10 P0 R0 S0 ; set initial tool 0 active and standby temperatures to 0C

    ; Custom settings are not defined

    ; Miscellaneous
    M911 S10 R11 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000"
    T0 ; select first tool



  • @johny

    Apart from having 3 thermistors setup with only 2 heaters, nothing jumps out at me as being odd.
    Could you take a photo of where you are connecting the thermistors?



  • Regarding to where i am connecting them its according to the wiring, also it is printed in the board E0 temp and bed heater :

    bead heater

    hot end heater

    Edit: i tried to connect to the E1 thermistor as well to check if it works that's why it have 3 thermistors setup



  • @johny

    Is the second image correct? that you are attaching the thermistor to the green terminals?



  • no sorry! In that i plug the heater, the thermistor is bellow
    alt text



  • I would set the values to the following

    M305 P0 T10000 B3950 R4700               ; set thermistor + ADC parameters for heater 0
    M143 H0 S120                             ; set temperature limit for heater 0 to 120C
    M305 P1 T100000 B4725 C7.060000e-8 R4700 ; set thermistor + ADC parameters for heater 1
    M143 H1 S280                             ; set temperature limit for heater 1 to 280C
    

    The P0 is a generic 3950 which is what tends to be used by chinese suppliers.
    The P1 is correct for a 104GT

    I would remove the P2 as this is probably confusing things.

    If you're still getting no values, I would revisit your crimping



  • I did those changes and i even solder a pair of wires directly to the bed thermistor to bypass any broken cable, the magic number is still there.
    Probably is something burn in the board, what could it be?
    Thank you



  • You could try remapping the bed thermistor to P2 and connecting to the e1 temp header and see if you get a reading



  • I did it, no luck, still same error :S
    I unplugged a thermistor from another printer to check it if was the thermistor and the same result.



  • (Don't think there is one)


  • @bearer said in Reading negative temperature and N/A temp:

    (Don't think there is one)

    Well i measure between the vssa and gnd and i got 3 ohms.
    I just checked that my heat bed had a short between the +12v and gnd but i got no readings even before plugging it.



  • What version of the firmware does M115 report? Might be useful in troubleshooting.



  • @blt3dp said in Reading negative temperature and N/A temp:

    M115

    M115
    FIRMWARE_NAME: RepRapFirmware for Duet 2 WiFi/Ethernet FIRMWARE_VERSION: 3.0 ELECTRONICS: Duet WiFi 1.02 or later FIRMWARE_DATE: 2020-01-03b3



  • @johny said in Reading negative temperature and N/A temp:

    FIRMWARE_VERSION: 3.0

    That's why you're not getting a reading, you need have to define the pin that it's using.



  • @johny

    Use

    ; Bed Heater
    M308 S0 P"bedtemp" Y"thermistor" T100000 B3950 C0 R4700				; Set thermistor + ADC parameters for heater 0
    M950 H0 C"bedheat" T0                               		; create bed heater output on bedheat and map it to sensor 0
    M307 H0 B0 S1.00
    M140 H0
    M143 H0 S130                               					; Set temperature limit for heater 0 to 120C
    
    ; Extruder Heater
    M308 S0 P"eotemp" Y"thermistor" T100000 B4275 C7.060000e-8  R4700							;
    M950 H1 C"e0heat" T1                                		; create nozzle heater output on e0heat and map it to sensor 1
    M143 H1 S400     
    


  • @jay_s_uk said in Reading negative temperature and N/A temp:

    @johny

    Use

    ; Bed Heater
    M308 S0 P"bedtemp" Y"thermistor" T100000 B3950 C0 R4700				; Set thermistor + ADC parameters for heater 0
    M950 H0 C"bedheat" T0                               		; create bed heater output on bedheat and map it to sensor 0
    M307 H0 B0 S1.00
    M140 H0
    M143 H0 S130                               					; Set temperature limit for heater 0 to 120C
    
    ; Extruder Heater
    M308 S0 P"eotemp" Y"thermistor" T100000 B4275 C7.060000e-8  R4700							;
    M950 H1 C"e0heat" T1                                		; create nozzle heater output on e0heat and map it to sensor 1
    M143 H1 S400     
    

    Yep, use that. In fact, looks like you're either modifying or creating a new config file based off of a RRF2x one. You might want to run through the web configurator and generate one for RRF3



  • I used and got a different error!
    fault on thermistor



  • cant detect sensor



  • Most likely your tool settings. Update these secttions.

    ; Heaters
    M308 S0 P"bedtemp" Y"thermistor" T100000 B4267 C7.06e-8 ; configure sensor 0 as thermistor on pin bedtemp
    M950 H0 C"bedheat" T0                                   ; create bed heater output on bedheat and map it to sensor 0
    M143 H0 S130                                            ; set temperature limit for heater 0 to 130C
    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
    M308 S1 P"e0temp" Y"thermistor" T100000 B4267 C7.06e-8  ; configure sensor 1 as thermistor on pin e0temp
    M950 H1 C"e0heat" T1                                    ; create nozzle heater output on e0heat and map it to sensor 1
    M143 H1 S275                                            ; set temperature limit for heater 1 to 275C
    M307 H1 B0 S1.00                                        ; disable bang-bang mode for heater  and set PWM limit
    
    ; Tools
    M563 P0 D0 H1 F0                                        ; define tool 0
    G10 P0 X0 Y0 Z0                                         ; set tool 0 axis offsets
    G10 P0 R0 S0                                            ; set initial tool 0 active and standby temperatures to 0C
    

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