I'm at a customer and they have bought a machine "as is" and it has a ge 90-30 siries plc with a 10 slot rack. In slot 10 there is a Horner 8 chanel thermocouple card. The problem is that none of the temps register in the plc memory. I can go online and change the value of a temp input and it will stay there.I can remove and/or short out the thermocouple and there is no change. It seem as if the back plane is bad but I'm not sure and could use some help determaning this. I have also replaced the input card with a new one with no change. The rest of the machine works well.