Devices in the
Ports class use the INF file msports.inf (in WINDOWS\inf), which contains the
device setup GUID for the Ports class. A USB virtual COM-port device must
also have a device-specific INF file as explained in Chapter 16.
COM Ports on PCs
41
3
For .NET??™s programmers, the SerialPort class provides a convenient way to
access COM-port devices. Other programming options include API functions
such as CreateFile, ReadFile, and WriteFile and software components from
Greenleaf Software, MarshallSoft Computing, Sax.net, and others. Chapter 9
and Chapter 10 have more about .NET programming.
Terminal-emulator utilities can provide a user interface for COM-port communications.
With a typical terminal emulator, you can type data to send, view
received data, and transfer files. Hilgraeve, Inc. (www.hilgraeve.com) provides a
free edition of the Hyperterminal utility for personal use as well as a business
edition of Hyperterminal and a more full-featured emulator called Hyper-
ACCESS. Windows editions through Windows XP include Hyperterminal,
accessed via Start > Programs > Accessories > Communications. Other terminal
emulators are available from a variety of sources. A popular free emulator is Tera
Term Pro.
#
PC programmers sometimes want to know how to access a UART??™s registers
directly.
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