Hey there,
PC communication with the Sunrise OS is quite possible and not too bad if you are familiar with Socket programming.
On the Java side, you will need a synchronous server up and running waiting for incoming commands from the PC. On the PC side, you will need a synchronous client that will connect to the KUKA with its IP address and a Port of 30000. Make sure that the port number is the one stated or communication via TCP/IP is not possible. The basic idea of this communication is that the PC will send strings to the KUKA, these strings will be parsed and treated as commands for the KUKA to use.
If you have furthur questions on how to figure this out shoot me a private message, and I'd be happy to show you further