Problems with 90-30 PLC

Hi, I have a 90-30 CPU 374 PLUS PLC. On that rack in slot 3 is a HE693RTD601M RTD module. Once or twice a week, we have faults show up in the Fault Table saying that there is a "Loss of I/O module" followed by a "Addition of I/O module" for that RTD module only. This happens really fast, and occurs 5-10 times a second, then resumes normal operation. Does anyone know what might be the cause of this?

I am also looking for an interim fix to this. Right now the module monitors coolant temperature, and turns fans on/off based on temperature. However, when there is that loss of module, the temperature reads 800 degrees C, and turns all the fans on, then when the module is found again, shuts the fans off. We can hear the fans turning on and off rapidly. Is there a way to hold the last value if a fault is detected?

Thanks

Have you tried to replace the rack sounds like a bad connection. Have you pulled out the card and reseated it?

I have pulled the card out and reseated it, but the problem still occurs. I will be replacing the backplane to see if it makes a difference.

I have seen this before with the same module, we ended up replacing the module to fix it. But I would first trade it and the module in slot 1 or 2 and see if that helps.