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The IEC 61850 I/O interface allows connecting to various IED through publishing and subscribing of GOOSE and Sampled Values messages. It also permits instantiating MMS servers in the simulator, in order to send reports to clients and to allow them to read or write data. Using a standard network interface card, this protocol can be easily and rapidly integrated into any simulation model.

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This standard extends the use of Sampled Values to customizable data sets and sampling rates. The content of an IEC 61869-9 SV message must be described in an SCL file, similarly to GOOSE messages.

IEC 61850-8-1 MMS

MMS is an international standard dealing with messaging systems for transferring real time process data and supervisory control information between networked devices or computer applications. In the IEC 61850 standard, it is the communication protocol chosen to implement a client-sever TCP/IP communication link.
There are two ways to exchange data between clients and servers: through reporting (initiated by servers) or polling (initiated by clients).
A report is an event based transmission of a data set's contents, according to specific trigger options. Its definition is found in an SCL file, similarly to GOOSE and SV IEC 61869-9. The file contains information about the data set the report uses, what its triggers are and which optional fields to include in the packet. When one of the trigger conditions is met, the server IED will send a report containing all data attributes of the concerned data set to all connected clients.
On the other hand, polling is done by the client by performing a direct read of a data attribute that is part of the server.

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