user manual

EIA-232-D Interconnections

A-6

Figure A-2 shows a way of wiring an EIA-232-D connector to enable

a computer to connect to a basic terminal with only three lines. This

is feasible because most terminals have a DTR signal that is ON,

and which can be used to pull up the CTS, DCD, and DSR signals.

Two of these connectors wired back-to-back can be used. In this

implementation, however, diagnostic messages that might

otherwise be generated do not occur because all the handshaking is

bypassed. In addition, the TX and RX lines may have to be crossed

since TX from a terminal is outgoing but the TX line on a modem is

an incoming signal.

Figure A-2. Minimum EIA-232-D Connection

GND 1

TxD 2

RxD 3

GND 7

RTS 4

CTS 5

DSR 6

DCD 8

EIA-232-D CONNECTOR

DTR 20

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