
DS6300 REFERENCE MANUAL
40
4
4.2.2 RS485
Full-Duplex
Interface
The RS485 full-duplex (5 wires + shield) 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 (3940 ft).
The following pins of the 25/26-pin connector are used for RS485 full-duplex interface
connection:
Pin Name
Function
2
TX+
RS485 output (+)
3
RX+
RS485 input (+)
4
TX-
RS485 output (-)
5
RX-
RS485 input (-)
7 GND_ISO
Main
signal
ground
DS6300
7
GND_ISO
TX+
2
TX-
4
RX+
3
RX-
5
+
SGND Main Isolated
USER INTERFACE
RX485
1
Earth
Ground
CHASSIS
-
+
TX485
-
Figure 56 - 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.
DS6300
7
GND_ISO
TX+
2
TX-
4
RX+
3
RX-
5
+
SGND Main Isolated
USER INTERFACE
RX485
1
Earth
Ground
CHASSIS
-
Figure 57 - RS485 Full-Duplex Connections using Only TX Signals