Interface X56.1

hey guys

I'm working on a spot welding project. I plugged all cables but one of them which is writes X56.1 and XPP1 on it. I don't even know what it is for.

I know where to plug X56.1 but I can't find the other pin (XPP1).

I made some research about these pins but I couldnt find anything but name of X56.1 interface that I saw it on the documantation for spot welding application from kuka xpert. unfortunatelly there is nothing else but the name of X56.1

here's the the components:

kr 210 r 3100-2

krc4

kuka technology cabinet

control panel

this is the url for that cable :

https://xpert.kuka.com/service-express/portal/project1_p/document/kuka-project1_p-basic_AR44297_en?context=%7B"filter"%3A%7B%7D,"text"%3A"00213772","useExpertQuery"%3A0%7D

thanks in advence..