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INSTALLATION
2
RS485 Full-Duplex Interface
The RS485 full-duplex interface is used for non-polled communication protocols in
point-to-point connections over longer distances than those acceptable for RS232
communications or in electrically noisy environments. The overall maximum cable length
should not exceed 1200 m (3937 ft).
The following pins of the 25-pin and 26-pin connector are used for RS485 full-duplex
interface connection:
Pin Name Function
2 TX485 + RS485 output (+)
3 RX485 + RS485 input (+)
4 TX485 - RS485 output (-)
5 RX485 - RS485 input (-)
7 GND_ISO Main signal ground
DX6400
7
GND_ISO
TX485+
2
RX485+
3
TX485-
4
RX485-
5
TX485+
TX485-
SGND Main Isolate
d
USER INTERFACE
RX485-
RX485+
1
Earth
Ground
CHASSIS
Figure 12 - RS485 Full-Duplex Interface Connections
NOTE
For applications that do not use RX485 signals, do not leave these lines
floating but connect them to GND_ISO as shown below.
DX6400
7
GND_ISO
TX485+
2
TX485-
4
RX485+
3
RX485-
5
SGND Main Isolated
USER INTERFACE
RX485-
RX485+
1
Earth
Ground
CHASSIS
Figure 13 - RS485 Full-Duplex Interface Connections Using Only TX Signals
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