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Chapter 4—Connections 63230-216-207/A3
Connecting 4-Wire Devices as 2-Wire 9/2002
© 2002 Schneider Electric All Rights Reserved
14
Biasing and Termination Each RS-485 port has built-in communications signal biasing and
termination circuitry. Thus, a multipoint communications adapter is not
needed. However, an end-of-line terminator (Square D part no. MCT-485 or
MCTAS-485) is required on the last device of each daisy chain. Refer to the
instruction bulletin for the last device on the daisy chain.
CONNECTING 4-WIRE DEVICES
AS 2-WIRE
Two DB9-to-terminal block adapters (female) [Square D part no. DB9F2TB]
are included with the Power Server. Use an adapter to connect a 4-wire
device as 2-wire to the Power Server. Refer to Figure 4–7 and follow these
steps:
1. On the DB9F2TB adapter, jumper the Rx+ and Tx+ terminals together,
and jumper the Rx– and Tx– terminals together.
2. Connect the Rx+/Tx+ terminals to the L+ line.
3. Connect the Rx–/Tx– terminals to the L– line.
4. Plug the DB9F2TB adapter into the RS-485 port on the Power Server.
Figure 4–7: Typical 2-wire POWERLOGIC device connection to Power
Server
L –
L +
Shield
1
2
3
4
5
6
7
8
9
Typical 2-wire
POWERLOGIC device
DB9F2TB to
Power Server
Tx –
Rx +
Shield
Tx +
Rx –
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