Siemens Argus 7SR22 - Page 391

Chapter 4 - Data Communications Definitions
© 2017 Siemens Protection Devices Limited Chapter 4 - Page 11 of 96
• Receiver sensitivity. The light power at the receiver must be above the sensitivity of the
receiver in order that effective communication can occur.
• A 3dB safety margin is usually allowed after the budget calculation is performed.
Following installation and prior to putting into service the actual losses should be measured for each fibre using a
calibrated light source and meter. Measured and calculated values can be compared.
The following table can be used to record budget calculations:
A Launch power
dB
B Fibre Type
C
D
Loss (dB/km)
Length
dB/km
km
E Total fibre loss (CxD)
dB
F No. of Splices
G Loss at each splice
dB
H
I
Total loss at splices (FxG)
No. of connectors
dB
J Loss per connector
dB
K Total loss at connectors (IxJ)
dB
L Total losses (E+H+K)
dB
M
N
Receive power budget (A-L)
Safety Margin
dB
dB
O Device Receive Sensitivity
dB
The following settings, on the COMMUNICATIONS MENU, must be configured when using the fibre Optic Com3
interface.
Setting Name Range/Options Default Setting Notes
COM3
Protocol
OFF
IEC60870-5-103
MODBUS-RTU
DNP3
IEC60870-5-103
The protocol used
to communicate on
the standard RS485
connection.
COM3
Station
Address
0 - 254 for IEC60870-5-103
1 - 247 for Modbus RTU
0 - 65534 for DNP3.0
0
An address within the
range of the relevant
protocol must be
given to identify the
relay. Each relay in a
network must have a
unique address.
COM3
75 110 150 300
The baud rate set
on all of the relays
600 1200 2400 4800
19200
connected to the
control system must
Baud Rate
9600 19200 38400
be the same as the
57600 115200 one set on the master
device.
The parity set on
all of the relays
COM3
Parity
NONE
ODD
EVEN
EVEN
connected to the
control system must
be the same and in
accordance with the
master device.