Dell POWEREDGE 4300, Installation And Troubleshooting Manual

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Running the Dell Diagnostics 5-21
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Serial External Transmission Test
If a loopback device is attached, checks the line control bits of the serial port and
sends a test pattern at several baud rates, checking the returned values
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If the diagnostics does not recognize the computer’s serial ports, enter the System
Setup program and check the Serial Port options to see whether the port has been dis-
abled. (See Chapter 4, “Using the System Setup Program,” in the
User’s Guide for
instructions.) The subtests in the Serial/Infrared 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 might behave erratically
or not operate at all. If the external device is not properly installed through the
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 configuration as the cause of the problem.
Another possible cause for errors is the external device. Use the documentation that
came with the peripheral to troubleshoot the device and confirm that it is working
properly.
After you eliminate incorrect system configuration information settings, peripheral
malfunctions, and software errors as potential causes of port problems, you can run
the subtests in the
Serial/Infrared Ports test group to check the hardware. Although
the following symptoms can be caused by faulty peripherals or software errors, they
might also suggest a port problem:
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If a peripheral works intermittently or produces intermittent errors, the port may
be faulty.
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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.
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If the software and the diagnostics do not recognize that you have a serial or
infrared port, you should check the
Serial/Infrared Port option in the System
Setup program and, if necessary, run the appropriate subtest in the Serial/
Infrared Ports test group.
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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 a par-
allel port. The subtests in this test group are not intended as diagnostic tests for the
actual peripheral attached to each port. (The only exception is a printer, as described in
the following subsection.)