P44x/EN IT/E33 Introduction
Page 22/24
MiCOM P441/P442 & P444
The next cell down the column controls the baud rate to be used:
Baud rate
9600 bits/s
IEC 60870-5-103 communication is asynchronous. Two baud rates are supported by the
relay, ‘9600 bits/s’ and ‘19200 bits/s’. It is important that whatever baud rate is selected on
the relay is the same as that set on the IEC 60870-5-103 master station.
The next cell down controls the period between IEC 60870-5-103 measurements:
Measure’t period
30.00 s
The IEC 60870-5-103 protocol allows the relay to supply measurements at regular intervals.
The interval between measurements is controlled by this cell, and can be set between 1 and
60 seconds.
The next cell down the column controls the physical media used for the communication:
Physical link
EIA(RS)485
The default setting is to select the electrical EIA(RS)485 connection. If the optional fibre optic
connectors are fitted to the relay, then this setting can be changed to ‘Fibre optic’.
The next cell down can be used to define the primary function type for this interface, where
this is not explicitly defined for the application by the IEC 60870-5-103 protocol*.
Function type
226
3.8.4 DNP 3.0 Communication
The DNP 3.0 protocol is defined and administered by the DNP User Group. Information
about the user group, DNP 3.0 in general and protocol specifications can be found on their
website: www.dnp.org
The relay operates as a DNP 3.0 slave and supports subset level 2 of the protocol plus some
of the features from level 3. DNP 3.0 communication is achieved via a twisted pair
connection to the rear port and can be used over a distance of 1000m with up to 32 slave
devices.
To use the rear port with DNP 3.0 communication, the relay’s communication settings must
be configured. To do this use the keypad and LCD user interface. In the relay menu firstly
check that the ‘Comms setting’ cell in the ‘Configuration’ column is set to ‘Visible’, then move
to the ‘Communications’ column. Four settings apply to the rear port using DNP 3.0, which
are described below. Move down the ‘Communications’ column from the column heading to
the first cell which indicates the communications protocol:
Protocol
DNP 3.0
The next cell controls the DNP 3.0 address of the relay:
DNP 3.0 address
232
Upto 32 relays can be connected to one DNP 3.0 spur, and therefore it is necessary for each
relay to have a unique address so that messages from the master control station are
accepted by only one relay. DNP 3.0 uses a decimal number between 1 and 65519 for the
relay address. It is important that no two relays have the same DNP 3.0 address.
The DNP 3.0 address is then used by the master station to communicate with the relay.
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