ABB RELION Series, Communication Protocol Manual

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The COM port connection type, optical ST or EIA-485 connection,
star or loop topology, idle state (light on or light off) and the bias and
bus termination are selected with the COM port jumpers.
3.2.2 TCP/IP mode
DNP3 TCP/IP link mode is supported by the protection relay.
The protection relay listens for a connection from a DNP3 client on port specified by
the user. Default values for TCP port number range from 20000...20004 depending on
instance number. A different port can be selected with the
TCP Port parameter.
DNP3 TCP/IP link mode and UDP broadcast are supported by the protection relay.
UDP broadcast requires that there is an active TCP connection by the client.
Documentation on DNP3 TCP/IP communication is available on www.dnp.org .
3.3 Communication setup
3.3.1 Communication modes
DNP3 communication can be set up in two alternative modes.
• Polled mode, called also “polled report by exception”. In this mode the DNP3
client always initiates the transaction with a read or write request to the DNP3
server. The server must reply with a response message.
• Unsolicited mode, called also “Unsolicited reporting mode”. In this mode the
DNP3 server may spontaneously send changed class events to the client. The
client can yet make additional read or write requests to the server.
By default, DNP3 operates in polled mode. Unsolicited reporting mode can be
activated with the
UR mode parameter.
3.3.2 DNP3 layer acknowledgements, retries and timeouts
It is possible to set up acknowledgements on both DNP3 link layer and application
layer. The settings should be equal on both the client and the server sides of the
communication. The timeouts must be set so that the other side has enough time to
prepare a positive acknowledgement. If an acknowledgement is received after the
configured timeout, it is discarded.
Confirmations, retries and timeouts can be configured via parameters.
Section 3
1MRS758757 A
Vendor-specific implementation
12 REC615 and RER615
Communication Protocol Manual