Getting weird ground signals with thermocouple

[diegoterc3]

Hello,

I am trying to make a reflow oven and have already made my first prototype for testing.
I can´t get my MAX6625 to read anything from the K type thermouple. I need help! On the datasheet it said that in order for the cold junction compensation to work the negative side of the thermocouple had to be connected to ground wich I did. When I meassure GND with an oscilloscope I get the negative thermocouple signal ofcourse. Will this make my MCU crazy?

Also I have some questions about the thermocouple wave form. Is it supposed to be this way? (see image).

Thank you!!

[Andy Watson]

I can´t get my MAX6625 to read anything from the K type thermouple.

Cannot read ?
or can read but data is garbage?

[diegoterc3]

Cannot read. I am cheking my code as well and debugging everything line by line to check if everything is ok.

[diegoterc3]

All right I made it work. The thermocouple wasn't making any contact to provide the signal.
But I would still like to know the answer. Would connecting the negative side of the thermocouple affect other digital devices because of the dynamic reference (GND)?

Thank you!