Hi V !
I think first of all you have to be sure that your robot is a safe version. That means a bigger RDC box and more cables to connect between RDC and controller. To my robot there is a cable which connect X40 from RDC to X21.2 on controller,there is also a X41 which connect to X21.1 and X31 to X21 which is for external axis , signal cable controller to RDC X21to X31 then from RDC to 7-th axis servomotor resolver.
If is safe robot I think you should have these two cables X40-X21.2 and X41-X21.2.
If the diagram you attached for controller sockets is like your real KRC2 , is not same with mine.
I only have X11 for standalone use made by diagram I sent you on email.
I am sending you also by email photos with my X11 bridges wiring but will not be easy to fallow each cable being many and close.
If you made X 11 ok is possible for robot, if safe, to need maybe two more cables between RDC and controller.
Check that.
Signum