The mini star-coupler allows SIPROTEC relays to be centrally accessed or remotely interrogated with DIGSI via optical interfaces.The component is cascadable, so that star topologies or ring topologies can be configured. A ring structure ensures that all four outputs are used. The ministar-coupler has a local RS232 interface socket. By connecting a PC to this interface and using the 7XV5100-4 cable, the optical input is disconnected to avoid data collision due to local and remote access concurring at the same time.