Bot is an ABB 6400 w/S4 controller.
On a cold start, I immediately get fault lights on the power supply and I/O boards, axis drive boards don't do anything.
Teach pendant says TPU lost contact.
First I checked voltages, power coming in is good, power to and out of the power supply is correct.
Anyone ever seen this error? and what exactly is the controller referring to as the TPU?
I will keep researching, if anyone has any insight it would be greatly appreciated, thanks.