Cabling Requirements; 2-Wire Connections - GE D400 Hardware User Manual

CHAPTER 4: CONNECTING TO DEVICES AND NETWORKS

Cabling requirements

2-Wire connections

To connect RS-485 2-
wire type devices to
the RS-485 Adapter
D400 SUBSTATION GATEWAY USER'S MANUAL
The recommended total maximum length for RS-485 cables is 4000 ft [1300 m] when
operating at 115 kbps. Refer to the manual of the connecting device for its recommended
maximum cable length.
The cables must be shielded and the shield of each RS-485 cable section should be
grounded at one end only. This prevents circulating currents and can reduce surge-
induced current on long communication lines.
The RS-485 Adapter supports a maximum of 32 transceivers of standard unit load per
channel (64 unit loads per RS-485 Adapter card).
Use the following wiring connection:
Before wiring devices, ensure that the RS-485 Adapter is configured to 2-wire mode (see
"RS-485 adapter" on page 37).
Figure 31: RS-485 2-wire devices - wiring connection
Relay
-
+
GND
RS485-
RS485+
Table 11: RS-485 2-Wire Terminal Block Signal Definitions
RS-485 Channel
Channel 1
Position Number 2-Wire
Function
1 TX1+
2 TX1−
3 FGND 1
4 RX1−
5 RX1+
GENERAL
RS-485 CONNECTIONS
Signal Flow
IN/OUT
IN/OUT
Shield
-
-
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