Sena Promi-SD 101 User Manual page 28

Promi-SD User Manual – 3. Connections
RS232C Interface
 RS232C
In the early 1960s, a standards committee, today known as the Electronic Industries Associatio n, developed a common
interface standard for data communications equipment. At that time, data communications was thought to mean
digital data exchange between a centrally located mainframe computer and a remote computer terminal, or possibly
between two t erminals without a computer involved. These devices were linked by telephone voice lines, and
consequently required a modem at each end for signal translation. While simple in concept, the many opportunities for
data error that occur when transmitting data through an analog channel require a relatively complex design. It was
thought that a standard was needed first to ensure reliable communication, and second to enable the
interconnection of equipment produced by different manufacturers, thereby fostering t he benefits of mass production
and competition. From these ideas, the RS232 standard was born. It specified signal voltages, signal timing, signal
function, a protocol for information exchange, and mechanical connectors. Refer the following site for detail s;
http://www.camiresearch.com/Data_Com_Basics/RS232_standard.html
 DTE/DCE
If the full EIA232 standard is implemented as defined, the equipment at the far end of the connection is named the DTE
device (Data Terminal Equipment, usually a computer or termina l), has a male DB9 connector. Equipment at the near
end of the connection (the telephone line interface) is named the DCE device (Data Circuit -terminating Equipment,
usually a modem), has a female DB9 connector. The cable linking DTE and DCE devices is a p arallel straight-through
cable with no cross -overs or self-connects in the connector hoods. If all devices exactly followed this standard, all
cables would be identical, and there would be no chance that an incorrectly wired cable could be used.
 DB9 Female
Promi -SD is a DCE device compatible with RS232 standard, having DB9 female interface.
Pin #
1
2
3
4
5
6
7
8
9
Signal Direction
CD Output
TxD Output
RxD Input
DSR Input
GND
DTR Output
CTS Input
RTS Output
Vcc Input
Copyright © 2006 Sena Technologies, Inc. All rights reserved.
Description
Received Line Signal Detect
Transmitted Data
Received Data
DTE Ready
-
Signal Ground
DCE Ready
Clear to Send
Request to Send
Ring Indicator
24