If your machine was delivered without a serial port, or if the built-in port fails,
another option is to downshift directly from a USB port to an old-fashioned
serial port. An example of a USB Serial Adapter is shown in Figure 16-2. The
Keyspan USB Serial Adapter is a plug-and-play device that adds a high-speed
serial port — as fast as 230 Kbps (twice the speed of a standard serial port)
and a device driver that manages the new hardware.
Testing a parallel port........................................................................
If you are still using a parallel port, or a parallel device that you’ve managed to
connect to a modern laptop, what do you do if the device stops responding?
Your first assignment is to determine which of the following is the problem:
The parallel port (or a USB to parallel port converter)
The parallel cable between the computer’s port and the printer or other
device
The device attached to the parallel cable
Figure 16-2:
The
Keyspan
USB Serial
Adapter
bridges
the gap
between a
modern
laptop with
a USB port
(or an
external
hub) and
an older
peripheral
that expects
a standard
RS-232
serial
connection.
Chapter 16: Breaking Out of the Box: PC Cards, USB, and FireWire 249