Been dealing with an issue on a heating/automation project I’ve been working on for several months now.
General plan is to heat 14 different zones on a vacuum chamber using 120V AC through high resistance wire regulated by solid state relays controlled by the arduino using a PID loop monitored by the MAX31855 system.
First, we had issues getting all 14 thermocouple boards reading, and ended up finding out that both the DO and CS lines need to be separate when you get above say 5 or so boards since things start to get strange.
At one point we switched to AD8495 analog thermocouple boards, but since we are using RF generated plasma in our chamber, we ran into grounding issues that the digital boards did not have, so we ended going back to digital.
The strange part is that with the analog, heating worked fine but not the thermocouples, but with digital, the thermocouple readings work fine but the heating is extremely delayed. Namely, it takes nearly 30 seconds per heating cycle versus the two seconds it took with analog.
I’m hoping someone can tell me looking at the code, what the issue is. Take in mind, I am not into coding, so please excuse my sloppy code. I am using a web based program to control and display the data by the way, so you might see code for that.
Any help is much appreciated!
PID_Final_3.ino (5.88 KB)