Sony Ericsson GM29, Integrator'S Manual, Page: 33 / 264

2. ELECTRICAL DESCRIPTION
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LZT 123 7361 R1B
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 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 > +4V
< –4V
Data carrier detect
2 RD O > +4V
< –4V
Received data
3 TD I > 2V
< 0.8V
Transmitted data
4 DTR I > 2V
< 0.8V
Data terminal ready
5 GND - 0V Ground connection
6 DSR O > +4V
< –4V
Data set ready
7 RTS I > 2V
< 0.8V
Request to send
8 CTS O > +4V
< –4V
Clear to send
9 RI O > +4V
< –4V
Ring indicator
9
1 DCD
2 RD
3 TD
4 DTR
5 GND
6 DSR
7 RTS
8 CTS
9 RI
7 6
5 4 3 2 1
8