It is recommended to enable biasing only at one end of the bus.
It is recommended to enable termination at each end of the bus.
It is recommended to ground the signal directly to earth from one node
using a GND pin and through capacitor from other nodes using a GNDC
pin.
Signal grounding should be used with all devices in RS-485 bus having an
isolated communication port. Grounding ensures that different RS-485
nodes have the same signal reference ground. Without grounding the
differential RS-485 signal might be superimposed between different
nodes with respect to the node's local ground. For signal grounding it is
recommended to connect to AGND pin in RS-485 connector an additional
ground wire which runs inside the shielded serial cable.
The optional communication modules include support for EIA-485 serial communication
(X5 connector). Depending on the configuration, the communication modules can host
either two 2-wire ports or one 4-wire port.
The two 2-wire ports are called COM1 and COM2. Alternatively, if there is only one 4-
wire port configured, the port is called COM2. The fiber optic ST connection uses the
COM1 port.
Table 959:
EIA-485 connections for COMB01A-COMB014A
Pin
2-wire mode
4-wire mode
10
COM1
A/+
COM2
Rx/+
9
B/-
Rx/-
8
COM2
A/+
Tx/+
7
B/-
Tx/-
6
AGND (isolated ground)
5
IRIG-B +
4
IRIG-B -
3
-
2
GNDC (case via capacitor)
1
GND (case)
1MAC059074-MB A
Section 13
Protection relay's physical connections
615 series ANSI
1153
Technical Manual
Summary of Contents for Relion 615 series
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