Siemens 7SR21 Manual page 9

There are two optional ports, com3 and com4, and when fitted the associated settings are available in the Data
Communication menu. To allow communication using either or both of these ports the relay settings must be
changed, via the fascia, in accordance with the method of connection and master device.
Setting name Range
1 – 254 for IEC60870-5-103
0 – 247 for Modbus RTU
Station Address
0 – 65520 for DNP3.0
OFF, IEC60870-5-103,
COM3 Protocol
MODBUS-RTU, DNP3.0
75 110 150 300 600 1200
2400 4800 9600 19200
COM3 Baud Rate
38400 57600 115200
NONE, ODD, EVEN
COM3 Parity
LIGHT ON, LIGHT OFF
COM3 Line Idle*
ON,OFF
COM3 Data Echo*
OFF, IEC60870-5-103,
COM4 Protocol**
MODBUS-RTU, DNP3.0
75 110 150 300 600 1200
2400 4800 9600 19200
COM4 Baud Rate**
38400
NONE, ODD, EVEN
COM4 Parity**
LIGHT ON, LIGHT OFF
COM4 Line Idle**
ON,OFF
COM4 Data Echo**
*Not applicable for RS 485 or RS 232 options
**COM 4 is fibre optic only
©2010 Siemens Protection Devices Limited
7SR21 & 7SR22 Data Communications
Default Setting
0 As Required
IEC60870-5-
As Required
103
57600 As Required
EVEN As Required
LIGHT OFF As Required
OFF As Required
IEC60870-5-
As Required
103
57600 As Required
EVEN As Required
LIGHT OFF As Required
OFF As Required
Notes
An address within the range of
the relevant protocol must be
given to identify the relay. Each
relay must have a unique
address.
Sets the protocol used to
communicate on the connection
– Com3
The baud rate set on all of the
relays connected to the control
system must be the same as
the one set on the master
device.
The parity set on all of the
relays connected to the control
system must be the same and
in accordance with the master
device.
Sets the idle state of the line in
accordance with master device
Set to ON when relays are
connected in a ring
configuration.
Sets the protocol used to
communicate on the connection
– Com4.
The baud rate set on all of the
relays connected to the control
system must be the same as
the one set on the master
device.
The parity set on all of the
relays connected to the control
system must be the same and
in accordance with the master
device.
Sets the idle state of the line in
accordance with master device
Set to ON when relays are
connected in a ring
configuration.
Chapter 4 Page 9 of 15