Thermisors showing wrong temperatures

mendelevium

@mendelevium
I am still struggling and hopefully someone can guide me.
I will explain what I have and what I am trying to achieve.
I have two daughterboards stacked on top of each other MAX31856-based interface boards
I have one heatbed H0 on channel 151, Hotend 0 on channel 150 and Hotend 1 on channel 152
I have type K thermocouples
This is how I configured my confg file.

;Heatbed configuration
M305 P0 X151
M950 H0 C"bedheat" T0 ; create bed heater output on bedheat and map it to sensor 0
M307 H0 B1 S1.00 ; enable 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

;Hotend 0 configuration
M305 P1 X150
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
M143 H1 S280 ; set temperature limit for heater 1 to 280C

;Hotend 1 configuration
M305 P2 X152
M950 H2 C"e1heat" T2 ; create nozzle heater output on e1heat and map it to sensor 2
M307 H2 B0 S1.00 ; disable bang-bang mode for heater and set PWM limit
M143 H2 S280 ; set temperature limit for heater 2 to 280C

Phaedrux

Here's what the config tool outputs when selecting thermocouple.

; Heaters
M308 S0 P"spi.cs2" Y"thermocouple-max31855" ; configure sensor 0 as thermocouple via CS pin spi.cs2
M950 H0 C"bedheat" T0                       ; create bed heater output on bedheat and map it to sensor 0
M307 H0 B1 S1.00                            ; enable 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"spi.cs1" Y"thermocouple-max31855" ; configure sensor 1 as thermocouple via CS pin spi.cs1
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
M143 H1 S280                                ; set temperature limit for heater 1 to 280C
M308 S2 P"spi.cs3" Y"thermocouple-max31855" ; configure sensor 2 as thermocouple via CS pin spi.cs3
M950 H2 C"e1heat" T2                        ; create nozzle heater output on e1heat and map it to sensor 2
M307 H2 B0 S1.00                            ; disable bang-bang mode for heater  and set PWM limit
M143 H2 S280                                ; set temperature limit for heater 2 to 280C

mendelevium

@phaedrux
Thank you, good morning, and I will try it out when I get back home. Stay Safe every one and we hope things get better for everybody.

mendelevium

@phaedrux
HI Still getting unknown sensor.. I have the Max 31856 not 31855
sensors are K type
thanks

mendelevium

@mendelevium
should the sensors read the room temperature? even when switched off??

Phaedrux

@mendelevium said in Thermisors showing wrong temperatures:

@phaedrux
HI Still getting unknown sensor.. I have the Max 31856 not 31855
sensors are K type
thanks

Ok so change it to thermocouple-max31856

dc42

@mendelevium said in Thermisors showing wrong temperatures:

@mendelevium
should the sensors read the room temperature? even when switched off??

Yes, they should read room temperature when the machine has not been heated up.

Please post your entire config.g file, and the result of running M98 P"config.g".

mendelevium

@dc42
The heaters now show a reading but they are spiking to 2000 deg
the bed also registers a fault..
what can I possibly have not right?
many thanks for your reply.

; Heaters
; Heatbed
M308 S0 P"spi.cs1" Y"thermocouple-max31856" ; configure sensor 0 as thermocouple via CS pin spi.cs1 and sensor type
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

; Hotend 1-e0
M308 S1 P"spi.cs2" Y"thermocouple-max31856" ; configure sensor 1 as thermocouple via CS pin spi.cs2 and sensor type
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
M143 H1 S280 ; set temperature limit for heater 1 to 280C

;Hotend 2-e1
M308 S2 P"spi.cs3" Y"thermocouple-max31856" ; configure sensor 2 as thermocouple via CS pin spi.cs3 and sensor type
M950 H2 C"e1heat" T2 ; create nozzle heater output on e1heat and map it to sensor 2
M307 H2 B0 S1.00 ; disable bang-bang mode for heater and set PWM limit
M143 H2 S280 ; set temperature limit for heater 2 to 280C

mendelevium

@dc42 said in Thermisors showing wrong temperatures:

M98 P"config.g
When I ran this command, I got a response too long message

Phaedrux

@mendelevium said in Thermisors showing wrong temperatures:

@dc42 said in Thermisors showing wrong temperatures:

M98 P"config.g
When I ran this command, I got a response too long message

check the console page

Phaedrux

@mendelevium said in Thermisors showing wrong temperatures:

The heaters now show a reading but they are spiking to 2000 deg
the bed also registers a fault..

When do they spike to 2000?

What fault did the bed give?

What does the heater graph look like?

mendelevium

@phaedrux

mendelevium

@phaedrux
The temperature will read 12.9/13 for both and then shoot up to 2000 deg in a flash and return to 12.9/13 but the room ambient temp is 23 deg C. I have read that the daughterboard had an improvement with a capacitor. I had bought it original from Duet around 2 years ago. might be this?

mendelevium

@mendelevium
Please note that I do not have a sensor daughterboard in place for the third heater.

Phaedrux

@mendelevium said in Thermisors showing wrong temperatures:

@mendelevium
Please note that I do not have a sensor daughterboard in place for the third heater.

Does that mean you have a thermocouple connected directly to the board?

Can you post a photo of your board setup?

Are you getting any heater fault messages in the console?

mendelevium

@mendelevium
Could someone explain how I can choose the right sensor as the heatbed has an NTC 100K thermistor and not a thermocouple.
The hot ends have a thermocouple

Phaedrux

@mendelevium said in Thermisors showing wrong temperatures:

@mendelevium
Could someone explain how I can choose the right sensor as the heatbed has an NTC 100K thermistor and not a thermocouple.
The hot ends have a thermocouple

M308 S0 P"bedtemp" Y"thermistor" T100000 B3950 ; 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
M307 H0 B1 S1.00                               ; enable 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

mendelevium

@phaedrux
I have a max31856 daughterboard

mendelevium

@phaedrux
No luck... the heatbed is connected to a MAX31856-based interface daughterboard. The headbed has an NTC 100k thermistor. Thank you.

dc42

@mendelevium said in Thermisors showing wrong temperatures:

@phaedrux
No luck... the heatbed is connected to a MAX31856-based interface daughterboard. The headbed has an NTC 100k thermistor. Thank you.

If the bed heater has a 100K thermistor then you should connect it to the bedtemp connector on the Duet, not to the daughter board. Your original line in config.g is nearly right:

M308 S0 P"bedtemp" Y"thermistor" T100000 B4138 ; configure sensor 0 as thermistor on pin bedtemp

except that B3950 is more likely to be a good match to the thermistor than B4138.

Edit: I just saw that @Phaedrux already gave you the correct config.g commands. But you still need to connect the thermistor to the bedtemp input, not the daughter board.