Thermisors showing wrong temperatures

[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...

[Phaedrux]

Thermocouples can be very particular about their wiring.

https://duet3d.dozuki.com/Wiki/Connecting_thermocouples#Section_Troubleshooting

[mendelevium]

@phaedrux
I have fitted two 0.01microfarad capacitors on each channel to earth as I had found on the forum however everything remained the same. Now I connected a new thermocouple to the board which is not touching anything and the problem remains.

[dc42]

@mendelevium,

1. Please post a photo showing the wiring between the daughter board and the thermocouple that is not connected to anything.

2. If you connect a wire link between the daughter board thermocouple terminals instead of connecting a thermocouple, what reading do you get?