Cl4424 user’s manual, 1 rs-232 – AeroComm CL4424 User Manual

Page 11

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CL4424 User’s Manual

6/21/2005

11

2.1

RS-232

RS-232 is a single ended data transmission protocol. The RS-232 signals are represented by
voltage levels with respect to a system common (power / logic ground). The "idle" state (MARK)
has the signal level negative with respect to common, and the "active" state (SPACE) has the
signal level positive with respect to common. RS-232 has numerous handshaking lines (primarily
used with modems), and also specifies a communications protocol.

Figure 5- RS-232 Male/Female Connector Pin out

RS-232 DB9 Female Connector

RS-232 DB9 Male Connector


Figure 6- DCE to DTE Interface


Pin

Description

1

DCD

2 RxD
3 TxD
4 DTR
5 GND
6 DSR
7 RTS
8 CTS
9 RI

Pin

Description

NC

DCD

2

TxD

3

RxD

4

DSR

5

GND

6

DTR

7

CTS

8

RTS

NC

RI

CTS

DTE

DCE

Straight Through Cable

CTS

RTS

RTS

RXD

TXD

TXD

RXD

GND

GND

DCD

DCD

DSR

DSR

DTR

DTR

OEM Host/PC

CL4424 Modem

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