User`s manual

8 Serial Port I/O
8-4
Overview of the Serial Port
This section provides an overview of the serial port. Topics include:
•What is Serial Communication?
•The Serial Port Interface Standard
•Connecting Two Devices with a Serial Cable
•Serial Port Signals and Pin Assignments
•Serial Data Format
•Finding Serial Port Information for Your Platform
For many serial port applications, you can communicate with your device
without detailed knowledge of how the serial port works. If your application is
straightforward, or if you are already familiar with the topics mentioned above,
you may want to begin with “The Serial Port Session” on page 8-19 to see how
to use your serial port device with MATLAB.
What Is Serial Communication?
Serial communication is the most common low-level protocol for
communicating between two or more devices. Normally, one device is a
computer, while the other device can be a modem, a printer, another computer,
or a scientific instrument such as an oscilloscope or a function generator.
As the name suggests, the serial port sends and receives bytes of information
in a serial fashion – one bit at a time. These bytes are transmitted using either
a binary (numerical) format or a text format.
The Serial Port Interface Standard
The serial port interface for connecting two devices is specified by the TIA/
EIA-232C standard published by the Telecommunications Industry
Association.
The original serial port interface standard was given by RS-232, which stands
for Recommended Standard number 232. The term “RS-232” is still in popular
use, and is used in this guide when referring to a serial communication port
that follows the TIA/EIA-232 standard. RS-232 defines these serial port
characteristics:
•The maximum bit transfer rate and cable length