In contrast, IP communication between the wind farm controller, the ENERCON control center and the PFC200 uses the “dictionary” of IEC 60870-5-104. “For us, the WAGO controller represents the largest communication node in the transformer station, and it manages everything,” explains the project manager. A third protocol, using IEC 60870-5-103, connects the technology within the transformer station. 103 communication represents the official standard in Europe for transmitting messages to digital protective equipment in the station control system. The protective devices can be understood here as slaves that transmit data cyclically or at the request of the master. In addition, signals are also received via digital inputs. Typical signals in a transformer station include door closure contacts, switch monitors and fill level or pressure sensors.