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I have 2 K-type thermocouples running on individual MAX31855 boards on a Raspberry Pi 3. The MAX31855 boards share a CLK pin but have separate CS and DO pins, similar to the set up given here: Multiple thermocouples on raspberry pi

Everything works great until i place both thermocouples on a metal surface which causes both thermocouple readings to be "NAN". I guess its a grounding issue? Is there a way to solve this?

Thanks in advance

rhys_j
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You can glue them with epoxy to the devices you are monitoring. Thermo-couples should not be connected together electrically and it sounds as though you may have grounded them. Also, I don't know how the MAX works precisely, but in order to be able to read negative temperatures, the thermo-couples are probably biased UP slightly (maybe 10mV).

If you ground them this means they will read a voltage that translates as -10mV which would be a temperature lower than absolute zero. Hence, NaN, i.e. not a number.

I do know how the TH7 works and the python code for driving that (its a raspberry pi thing) is here https://github.com/robin48gx/TH7

user50619
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