Dell Dimension XPS D Series, Reference And Troubleshooting Manual, Page: 116 / 191

7-16 Dell Dimension XPS Dxxx Systems Reference and Troubleshooting Guide
If an external loopback connector (a special Dell manufacturing device) is not attached
to a serial port, the External Transmission Test will fail for that port and the results of
this test should therefore be ignored. An external modem connected to the port does
not substitute for an external loopback connector.
3DUDOOHO3RUWV7HVW*URXS
The Parallel Ports Test Group checks the computer’s interface with a device con-
nected to the computer through the parallel port. It does not test the device itself,
except for the Printer Pattern Test. Table 7-10 lists the tests.
If the Dell Diagnostics does not recognize your computer’s parallel port, enter the sys-
tem setup program and verify that the parallel port is enabled. The Parallel Ports Test
Group cannot test a port unless it is enabled.
When a port is faulty, first make sure that the device connected to the port functions
properly. Use the documentation that came with the device to troubleshoot it and
confirm that it is working properly. Try operating the device from different programs or
through the operating system to eliminate the software configuration as the cause of
the problem.
After you eliminate incorrect system configuration settings, device malfunctions, and
software errors as potential causes of port problems, run the Parallel Ports Test Group
to check the system hardware. Although faulty devices or software errors may cause
the following symptoms, they also suggest a port problem:
‡
If a device 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 test in the Parallel Ports Test Group.
7DEOH6HULDO,QIUDUHG3RUWV7HVW*URXS
7HVW 'HVFULSWLRQ
Baud Rate Checks the baud rate generator in each serial commu-
nications chip against the computer’s clock.
Interrupt Checks the serial port’s ability to send IRQs to the
microprocessor.
Internal Transmission Checks several internal functions of the serial port
using the internal loopback mode of the serial commu-
nications chip.
External Transmission If a loopback connector is attached, checks the line
control bits of the serial port and sends a test pattern
at several baud rates, checking the returned values.
NOTE: The Glossary in the Online Guide defines abbreviations and acronyms.