If you don't need actual real time, but small latency (12 ms) is fine: either JOpenShowVar or Kuka Ethernet KRL. The latter is a paid option from Kuka.
RSI is the "hard realtime" option. It can do what you're trying to accomplish, but the timing requirements are very rigid. So your "server" program that RSI is communicating with will need to be fast and robust.
"i cant find that much information about rsi online"
then internet, computers and programming are just not for you. you could read pinned topic READ FIRST and see how and where to get information. lots of it is on this forum and more can be downloaded from KUKA portal called Xpert. yes, 99% of all options are paid options. and RSI is expensive. some 4x the cost of Ethernet KRL but mere peanuts compared to FastSendDriver.
getting ProfiNet card for your PC is one option but you still need ProfiNet for your KRC4 as well. that is a paid option of course and it may or may not work for you. need to check compatibility with any other options that your KRC4 may have.
did you try to google for "rsi"? you won't find related hits. but it you change search to "kuka rsi" you will get bunch of manuals in first few hits.
read first topic contains info where to get info, including download section of this forum and how and where to get manuals from kuka. forum also has search function and RSI returns more than 250 hits.
finally, one can also contact KUKA and ask for advice, quote and manuals. then you know the prices and get exactly what you need - even if you don't end up buying it.
btw communicating with "robot" is really communicating with controller. type of robot arm has nothing to do with this but you may want to check what software is installed. you already mentioned KSS but not installed options. if you are i Europe, ProfiNet is very common. if you are in North America, EthernetIP is much more common. both use same resources and therefore cannot be used at the same time.
also to get selection narrowed down, you need to be more specific about actual needs. is this one way or two way communication, how fast, how much data etc.
there is plenty of responses with things to explore.
Both ProfiNet and EthernetIP use virtual5 of KLI. Therefore they cannot be installed at the same time.
RSI is "realtime" motion control. It can work over a TCP/IP connection, or over any FieldBus (EIP, ProfiNet, DeviceNet, etc) that has been installed and configured on the KRC. The KRC4 can support almost any of the common industry FBs, but they each require adding either software or hardware options. RSI updates every 12ms (4ms for some configurations).
EthernetKRLXML (EKI) is the official KUKA option package to enable KRL programs to use TCP/IP (or UDP) connections. This is non-realtime interface, but a well-written SPS program can crudely approximate an RSI connection. For simple position reporting, this would probably serve.
OpenShowVar is an unofficial 3rd-party option that operates rather like EKI. I've never used it, but my understanding is that it can "expose" global variables on the robot to a remote system over TCP/IP, without needing any paid KUKA options.
OPC Server is a KUKA paid add-on that, in the robot, looks/feels like a FieldBus. The main difference is that OPC can work on regular PCs without requiring special hardware add-ons (unlike, say, ProfiNet). OPC's other big advantage is that it's an open standard that almost all automation brands support, unlike (for example) the Profinet/EIP divide.
Hi Julian
It really depends on "how much realt time" you want.
RSI can cycle at 4 ms, no lower than that.
A much simpler way to do that is using EKI (ethernet Kuka inteface). Program the submit interpreter to read the $AXIS_ACT variable every cycle and send it via TCP.
Clearly this second option is not hard real time. The cycle time of the submit is not fixed, but with few simple commands stays around 12 ms/cycle, but yes, is not fixed as the submit shares cpu resources with the robot interpreter so it may vary
