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10 Communication
10.1 General
This section outlines the remote data communication interfaces of this relay. The relay can support
several protocols: IEC60870-5-103, IEC61850 and DNP3.0. Setting the relevant communication
parameter can select the expected protocol (see Section 7.6).
The EIA RS-485 standardized interfaces are isolated, as well as the Ethernet interfaces, and are
suitable for permanent connection whichever protocol is selected. The advantage of t his type of
connection is that up to 32 relays can be "daisy chained" together using a simple twisted pair
electrical connection.
It should be noted that the descriptions contained within this section do not aim to fully detail the
protocol itself. The relevant documentation for the protocol should be referred to for this
information. This section serves to describe the specific implementation of the protocol in the relay.
10.2 Rear Communication Port Information
10.2.1 RS-485 Interface
This relay provides some rear RS-485 communication ports, and each port has two terminals in
the screw connector located on the back of the relay. This port has a common ground terminal for
the earth shield of the communication cable. See Section 6.5 for details of the connection
terminals. The rear ports provide RS-485 serial data communication and they are intended for use
with a permanently wired connection to a remote control center.
The protocol provided by the relay is indicated in the relay's "Comm Settings" submenu (see
Section 7.6). By using the keypad and LCD, configure the relevant communication protocol
parameters, the corresponding protocol and will be selected.
10.2.1.1 EIA RS-485 Standardized Bus
The EIA RS-485 two-wire connection provides a half-duplex fully isolated serial connection to the
product. The connection is polarized and whilst the product's connection diagrams indicate the
polarization of the connection terminals it should be noted that there is no agreed definition of
which terminal is which. If the master is unable to communicate with the product, and the
communication parameters match, then it is possible that the two-wire connection is reversed.
10.2.1.2 Bus Termination
The EIA RS-485 bus must have 120Ω (Ohm) ½ Watt terminating resistors fitted at either end
across the signal wires (see Figure 10.2-1). Some devices may be able to provide the bus
terminating resistors by different connection or configuration arrangements, in which case
separate external components will not be required. However, this product does not provide such a
facility, so if it is located at the bus terminus then an external termination resistor will be require d.
10-1
PCS-9611 Feeder Relay
Date: 2014-04-08
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