The USB (Universal Serial Bus) Solution
A new computer finally arrives. It has
lightning speed, the latest operating system, and a RWCD.
Then you notice the manufacturer has shipped the computer
without the standard DB-9 serial ports. If a serial port is
being used on the computer this is replacing, what can be
done? There is an easy solution to this, the USB to Serial
converter.
Most computers today will ship with at
least two USB ports. For a lot of individuals, this will not
be enough to handle all the devices that need to connect to
the computer. For example a USB mouse and keyboard are common,
and when a printer and Personal Data Assistant is added it
can be seen that more ports are needed.
The easiest solution to this is to add
a USB hub. Most hubs will support the addition of four or
more peripheral devices. Hubs can be added to extend the distance
a USB device can be away from the computer, along with adding
ports. The maximum distance a standard USB cable should be
is 5 meters. With the addition of USB hubs the distance can
be extended to 30 meters using a 5-meter cable between each
hub.
Windows operating systems that support
USB (Windows 98 SE, ME, 2000 and XP) will automatically detect
the USB peripheral device when connected to the USB port.
The setup wizard steps through the installation asking for
the drivers and setting up the Com Port when installing USB
to serial converters. After a USB device is configured in
an operating system the device can be connected and disconnected
at any time.
USB also provides a solution for parallel
printers that are currently connected to parallel ports and
do not have USB support. These are designed to work exclusively
with printers. Standard USB to parallel converters are also
available.
A lot of development is underway to allow
an easy transition to USB by many companies. One example would
be USB devices that are now available allowing Windows NT
4.0 operating systems, which normally will not support USB,
access to USB ports. The purpose of this is to facilitate
the addition of several serial ports or a printer port to
the computer with a single USB connection. A single USB device
may contain four serial ports or two serial ports and a parallel
printer port. For most users this may be easier than the traditional
methods of adding ports to a computer.
Most USB to serial converters will load
in the operating system and show up in the device manager
as a new Com Port. Most install on the next available Com
Port in the operating system. At this time the USB to serial
converters include a RS-232 or RS-422/485 interface. Converters
can also include optical isolation for use in harsh environments.
To incorporate USB with currently used
software is a workable solution for most users. Only programs
designed to communicate to an I/O address and IRQ are the
exception. Most programs that have been written and use the
normal Windows API call will be able to access a USB port.
RS-232 converters can include full hand shaking capabilities
if supported by the software being run on the computer. Hyper
Terminal is an example of a program found commonly on Windows
operating systems which will support any USB or serial COM
Port that loads on COM 1-4. Other software programs will commonly
support most USB COM Port numbers that load above COM 4.
The introduction of USB may seem a little
confusing but with the correct support from manufacturers
the users will find it a useful and easy transition.
For more information on USB, we recommend
USB
Complete, USB
Hardware and Sofware, and USB
Explained.
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