2.5RS232 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

Description

 

 

 

 

 

 

 

levels

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

 

DCD

 

O

 

> +4 V

 

Data carrier detect

 

 

 

 

 

 

 

 

< –4 V

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2

RD

 

O

> +4 V

Received data

 

 

 

 

 

 

 

< –4 V

 

 

 

 

 

 

 

 

 

 

 

 

 

3

 

TD

 

I

 

> 2 V

Transmitted data

 

 

 

 

 

 

 

< 0.8 V

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4

 

DTR

 

I

 

> 2 V

Data terminal ready

 

 

 

 

 

 

 

< 0.8 V

 

 

 

 

 

 

 

 

 

 

 

 

 

5

 

GND

-

 

0 V

Ground connection

 

 

 

 

 

 

 

 

 

 

 

6

 

DSR

 

O

 

> +4 V

Data set ready

 

 

 

 

 

 

 

< –4 V

 

 

 

 

 

 

 

 

 

 

 

 

 

7

 

RTS

 

I

 

> 2 V

Request to send

 

 

 

 

 

 

 

< 0.8 V

 

 

 

 

 

 

 

 

 

 

 

 

 

 

8

 

CTS

 

O

 

> +4 V

Clear to send

 

 

 

 

 

 

 

< –4 V

 

 

 

 

 

 

 

 

 

 

 

 

 

9

 

RI

 

O

 

> +4 V

Ring indicator

 

 

 

 

 

 

 

< –4 V

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Owner’s Manual

 

 

 

 

Rev 1.0

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