Hi guys!
Bridgeport VMC 800 with Heidenhain TNC 426PB.

Get alarms concerning spindle motor encoder amplitude.
I usually try change interface port on the TNC first. Normally the spindle motor encoder is connected to X19 and usually the X20 is free.
At least on TNC 530 You just change values in MP 113, but in this version of the controller MP113 is not present and so isn´t MP112 for the corresponding axes control.
According to the regional Heidenhain office, this feature isn´t available on this version of the controller. The port addressed (or numbers) are somewhat hardwired in the system, so we don´t have the liberty to change inputs as we see fit. Well, this i could accept if it wasn´t for one thing. The spindle motor encoder cable that is supposed to sit at X19 was already put on X20 when I was enrolled to repair the machine, and it has been that way for years - working. I´m pretty sure the normal position is X19 for this machine as that correspond to the schematics and the marking on the cable itself. Now there is a crude piece of tape with marker saying X20 on the cable.
If I knew who made the modification of course I´d ask him HOW? But now... Do anybody have a clue how this was done without changing the nonexisting MP113?