MikeCF (Customer) asked a question.
I have two different systems that are having the same issue. Randomly the P1-04THM type-k temperature readings will start bouncing all over - from negative to very positive numbers. I have verified the system grounding. I'm using all the thermocouple inputs. Ungrounded type. Shielded cable. I've run the thermocouples to a process controller and the readings are stable. I've tried powering the P1-540 CPU with 120V and then with 24VDC with the same result. There are some times where it will on be one channel and then eventually all channels are bouncing. I put a small cooling fan over the cards and that seemed to help - although the panel temperature never gets above 95F. I ended up putting thermocouple to mA converters in and it's working fine. Something is pointing at those thermocouple cards, but I'm not sure what. Any comments are welcome.
I have experienced the same but with the P2-08THM modules on a P2K PLC. How I solved this was by using just one channel per module. Not exactly a cost effective solution but the only way I found to work around this issue. Hopefully tech support can provide a better recommendation.