AeroComm CL4490-1000 - Manual (Page 11)

CL4490 User’s Manual
1.4 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
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
Figure 6- DCE to DTE Interface
CL4490 Modem OEM Host/PC
DTR
DSR
DCD
DTR
DSR
DCD
GND GND
RXD
TXD
TXD
RXD
CTS CTS
RTS
RTS
DCE
DTE
Straight Through Cable
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