Sony Ericsson TT4031 (SE-GM29) Manual

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Owner’s Manual Rev 1.0 Page 34 of 34

2.5 RS232 Serial Port

The modem supports a standard RS232 serial interface (EIA/TIA 574) via

its 9 pin Sub-D connector, shown below. In line with serial communication

terminology the TT4031 (SE-GM29) serial modem should be considered as

the data circuit-terminating equipment (DCE) and the external application

or computer as the data terminating equipment (DTE).

The electrical characteristics of the serial port signals are shown below:

Pin Signal Dir Voltage

levels

Description

1 DCD O > +4 V

< –4 V

Data carrier detect

2 RD O > +4 V

< –4 V

Received data

3 TD I > 2 V

< 0.8 V

Transmitted data

4 DTR I > 2 V

< 0.8 V

Data terminal ready

5 GND - 0 V Ground connection

6 DSR O > +4 V

< –4 V

Data set ready

7 RTS I > 2 V

< 0.8 V

Request to send

8 CTS O > +4 V

< –4 V

Clear to send

9 RI O > +4 V

< –4 V

Ring indicator