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Overview
1-4
NET485 User Guide
1.2.2 RS422 Operation
The NET485 can handle both RS485 and RS422 communications. This is done by connecting the processor
(CPU) to a pair of RS485 transceivers. The following schematic demonstrates how the circuit is wired for
RS422.
For RS422 mode, use the four signals produced by the two transceivers plus a signal ground as shown in
Figure 1 – RS422 Wiring
D
R
Vcc
3.3V
DE
DI
RO
RE
GND
8
3
4
1
2
5
7
6
6
D
R
Vcc
3.3V
DE
DI
RO
RE
GND
8
3
4
1
2
5
7
6
TXDA (Pin 7)
TXDB (Pin 6)
RXDA (Pin 5)
RXDB (Pin 4)
3.3V
CP0
TX
4
RX
5
Vcc
3.3V
2
GND
1
3.3V
RS422
Half-Duplex
Mode
SGND (Pin 3)
2
1
3
R13
10K
J2
CPU
TXDA
TXDB
RXDA
RXDB
SGND
Figure 1 – RS422 Wiring
The transmit section of the CPU is labeled TX on pin 4. The receive section of the CPU is labeled RX on
pin 5. Note that the
CP0
pin on the CPU pin 6, which is configured to control the level of RS485_TXEN, is
connected to both transceivers. The transmit section is enabled with a High signal on pin 3, U2 and the
receive section is enabled with a Low signal on pin 2, U4.
There is a jumper option J2 that permits RS485/RS422 Half Duplex or RS422 Full Duplex. With the jumper
in the factory set position between pins 2 and 3, the unit is set for RS485/RS422 Half Duplex.
Summary of Contents for NET485
Page 1: ...NET485 RS422 485 Serial to Ethernet Adapter Revision E October 14 2013 ...
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Page 60: ...Tables 7 2 NET485 User Guide Click Hex The hexadecimal value displays ...
Page 62: ...Tables 8 2 NET485 User Guide 8 1 Certificate of Compliance ...