Dell Latitude LM - Manual (Page 75)

Running the Dell Diagnostics 4-19
If the external device is not properly installed through
software, the device also may not function properly. Try
operating the device from different programs or through
the operating system. If it still does not work, you can
eliminate the software configuration as the cause of the
problem.
Although the following symptoms can be caused by
faulty peripherals or software errors, these symptoms
might also suggest a port problem:
• If a peripheral works intermittently, or produces
intermittent errors, the port may be faulty.
• If the computer displays an error message that is
related to the external device connected to a port, but
corrections to the device do not resolve the error, run
the appropriate subtest in the Serial/Infrared Ports
Test Group.
Subtests
The four subtests in the Serial/Infrared Ports Test Group
confirm the following port functions:
• Serial/IR Baud Rate Test
Checks the baud rate generator in each serial com-
munications chip against the computer’s clock
• Serial/IR Interrupt Test
Checks the serial port’s ability to send IRQs to the
microprocessor
• Serial/IR Internal Transmission Test
Checks several internal functions of the serial port
using the internal loopback mode of the serial com-
munications chip
• Serial External Transmission Test
If a loopback device is attached, checks the line con-
trol bits of the serial port and sends a test pattern at
several baud rates, checking the returned values
P
arallel Ports Test Group
The subtests in the Parallel Ports Test Group check the
computer’s interface with external devices, such as a
printer, that are connected to the computer through the paral-
lel port. The subtests in this test group are not intended as a
diagnostic test for the actual peripheral attached to each port.
Why Run a Parallel Ports Test?
If the diagnostics does not recognize the computer’s par-
allel port, check the
PARALLEL MODE system setup option
to see if the port has been disabled. For instructions, see the
topic titled “Peripherals Menu” in the online System User’s
Guide. The subtests in the Parallel Ports Test Group cannot
test a port unless it is enabled.
When a port is faulty, it may not be immediately evident
that the port, and not the device connected to the port, is
faulty. Instead, the peripheral (such as a printer) might
behave erratically or not operate at all. If the external
device is not properly installed through software, it also
may not function properly. Try operating the peripheral
from different programs or through the operating system.
If it still does not work, you can eliminate the software
setup as the cause of the problem.
Another possible cause for errors is a problem with the
external device itself. Use the documentation that came with
the peripheral to troubleshoot it and confirm that it is work-
ing properly. (Most printers have a self-test.)
After you eliminate incorrect system configuration infor-
mation settings, peripheral malfunctions, and software
errors as potential causes of port problems, you can run
the subtests in the Parallel Ports Test Group to check your
hardware. Although the following symptoms can be
caused by faulty peripherals or software errors, they
might also suggest a port problem:
• If a peripheral works intermittently, or produces
intermittent errors, the port may be faulty.
• If the computer displays an error message that is
related to the external device connected to a port, but
corrections to the device do not resolve the error, run
the appropriate subtest in the Parallel Ports Test
Group.
• If your software and the diagnostics do not recognize
that you have a parallel port, you should check the
PARALLEL MODE system setup option, and if necessary,
run the appropriate subtest in the Parallel Ports Test
Group.