GE D20 - RS-485 Cable Wiring and Transient Suppression

D20/D200
Installation and Operations Guide
GE Energy
994-0078-2.00-7 General
50
Full
Connections and Configuration, continued
2-Wire RS-485
Cable
Schematic of the cable wiring necessary for 2-wire RS-485 operation. The pin
pattern is as seen from the back of the DB9-F connector.
5
9
4
7
2
6
1
+
–
TX/RX
3
8
4-Wire RS-485
Cable
Schematic of the cable wiring necessary for 4-wire RS-485 operation. The pin
pattern is as seen from the back of the DB9-F connector.
5
9
4
3
7
6
1
+
+
–
–
8
2
RX
TX
Transient
Suppression
The RS-485 port on the D20ME II provides no isolation and offers limited built-in
transient suppression. If you are using the D20ME II in an environment where longer
cable runs with larger transients are expected, installation of an external transient
suppression device is recommended to protect the RTU. In addition, GE
recommends the installation of an external transient suppression device when the
RS-485 communication cable must be run to devices located outside of the RTU
cabinet containing the D20ME II. Contact customer service for additional
inform
ation.