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Group
Jumper connection
Description
2-3
EIA-232
To ensure fail-safe operation, the bus is to be biased at one end using the pull-up
and pull-down resistors on the communication module. In the 4-wire connection,
the pull-up and pull-down resistors are selected by setting jumpers X5, X6, X8, X9
to enabled position. The bus termination is selected by setting jumpers X7, X11 to
enabled position.
The jumpers have been set to no termination and no biasing as default.
Table 741: 2-wire EIA-485 jumper connectors for COM1
Group
Jumper
connection
Description
Notes
X5
1-2
2-3
A+ bias enabled
A+ bias disabled
1
COM1
Rear connector X6 2-
wire connection
X6
1-2
2-3
B- bias enabled
B- bias disabled
1
X7
1-2
2-3
Bus termination enabled
Bus termination disabled
1
Table 742: 4-wire EIA-485 jumper connectors for COM1
Group
Jumper
connection
Description
Notes
X5
1-2
2-3
A+ bias enabled
A+ bias disabled
1
COM1
Rear connector X6 4-
wire TX channel
X6
1-2
2-3
B- bias enabled
B- bias disabled
1
X7
1-2
2-3
Bus termination enabled
Bus termination disabled
1
X9
1-2
2-3
A+ bias enabled
A+ bias disabled
1
4-wire RX channel
X8
1-2
2-3
B- bias enabled
B- bias disabled
1
X11
1-2
2-3
Bus termination enabled
Bus termination disabled
1
COM2 port connection can be either EIA-485 or optical ST. Connection type is
selected by setting jumpers X27 and X28.
1
Default setting
Protection relay's physical connections
1MRS758755 C
846
REC615 & RER615
Technical Manual