Thermisors showing wrong temperatures

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.

mendelevium

@dc42
So the thermistor is plugged directly into the board while the thermocouples into the daughterboard right?

dc42

@mendelevium said in Thermisors showing wrong temperatures:

@dc42
So the thermistor is plugged directly into the board while the thermocouples into the daughterboard right?

Yes, correct.

mendelevium

@dc42
Thank you the bed sensor is working and reading a reasonable temperature
the hot end temperatures are not well... One is reading 2000deg all the time. The other spikes at 2000deg for a split second then goes to a low unrealistic temperature.

Phaedrux

Are you using extension wires on the thermocouples?

mendelevium

@phaedrux
yes of course but i have over 2 m of wireing. may try to connect a thermocouple directly and see the reading...