Specifications

30 Chapter 6 EIA-422 asynchronous interface
Digi EIA-422 connector wiring
A terminal, a serial printer, or a serial port for another computer usually
functions as a DTE device. A Digi adapter is also a DTE device. To connect
a DTE device to another DTE device a null modem cable or adapter must
be used.
Two wires (one twisted pair) are required for each signal: a positive lead
(“+”), and a negative lead (“-”). The “+” leads at one end of the cable must
be connected to the “+” leads at the other end, and the “-” leads at one end
must be connected to the “-” leads at the other end.
Caution: Incorrect wiring could result in damage to the connected devices.
The following table shows the pin configurations for the EIA-422 versions
of Digi DB-9, DB-25, and RJ-45 connectors.
Signal Description DB-9 pin DB-25 pin
RJ-45
10-pin
Optional
RJ-45
8-pin
(2 wire)
TxD+ Transmitted Data (+) 8 2 5 N/A
TxD- Transmitted Data (-) 9 14 1 1 (Data -)
RxD+ Received Data (+) 6 3 6 5 (Data +)
RxD- Received Data (-) 7 16 2 N/A
RTS+ Request To Send (+) 2 4 3 N/A
RTS- Request To Send (-) 3 19 9 N/A
CTS+ Clear To Send (+) 4 5 8 N/A
CTS- Clear To Send (-) 5 13 10 N/A
GND Chassis Ground Shell Shell 4 N/A
SG Signal Ground -
-
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