In the mid-nineties, integrated substation automation and protection solutions had become quite popular in Europe. While the station bus communication between bay controllers and the station level devices was mainly based on vendor specific protocols, the German Standardization organization DIN had standardized a SCADA interface to protection relays which later became the IEC 60870-5-103 standard.
In 1994, the scope for IEC 61850 was prepared. It did not only include the well-established communication between protection and control IEDs (bay level) and the station level devices (e.g. gateway or Station HMI). The scope added a communication down to the process level, which was later known as process bus. And some vendors had the first concepts of such communication.