Client/Server

Client/Server services are one-to-one type communication. The communication is initiated by the client request, followed by the server answering with a response. Typical and often used group of client/server services are

• Association

• Discovery

• DataSets

• Setting Group

• Report

• LOG

• Control

• File transfer

For the most, the Client/Server services in the ACSI is a definition of requests a client can send to the server and the according response for this request.

Report

The report is a special case Client/Server service. It is spontaneous, because the server is sending a report on defined trigger events. It is still a Client/Server service because it is based on TCP/IP. For a report to work, the client must once enable the report and reserve it for the client. Then the client is waiting for reports coming in triggered by configured events.

Mapping to MMS

Services defined in the ACSI is abstract. In the substation domain, those are mapped to the manufacturer massaging specification. It must be mapped because you cannot assume both are the same in all details. Take e.g. the series of control services: Operate, Chancel, SelectWithValue. MMS does not any of such thing. The mapping is done with the MMS write request, which is capable of writing not only basic values but also a complete data structure. To be able to map an extra data structure was designed called Oper, Chancel and SBOw. Its data is not reflecting any data in the IED, but is there only to allow control service operation through MMS. In other words, when control services are applied through mapping to MMS it is done by writing a very specific data structure in the data model of the IED.