Note: The word "client" refers to the protocol master. The protection relay is referred to as "server" or a slave device.
The protection relay can communicate with several protocol clients simultaneously. Furthermore, it is possible to configure the protection relay to provide different protocol data and data outlook for different clients. A protocol server communication entity which is configured to operate with a specific master or client is called an instance.
There are three server instance scenarios.
- One client - One protocol instance - One protocol mapping. The protection relay is intended to operate toward one protocol client. The default protocol data mapping or data outlook can be modified freely.
- Several clients - Several protocol instances - One protocol mapping. The protection relay is intended to operate toward several protocol clients. All the clients should be able to access exactly similar data or similar data outlook. The default protocol mapping or data outlook can be modified freely.
- Several clients - Several protocol instances - Several protocol mappings. The protection relay is intended to operate toward several protocol clients. Some or all of the clients may want to access protocol data in a different manner. For this purpose, several protocol mappings derived from the default protocol mapping need to be prepared.