User's Manual

ManualsBrandsStandard Horizon ManualsModemsStandard Horizon Standard Horizon Modem GM29

2. ELECTRICAL DESCRIPTION

LZT 123 7361 R1A

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

1 DCD

2RD

3TD

4 DTR

5 GND

6 DSR

7RTS

8 CTS

9RI

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