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7.
TROUBLESHOOTING
7.1
General Approach
When troubleshooting problems, a rational plan can save you many
hours of frustration. The following is a brief outline of standard
troubleshooting procedures.
1.
Gather the facts to determine the exact nature of the problem.
2.
Draw a picture of the system showing the equipment at both
the host and remote ends and the phone lines or in-house
wiring. Use this as a reference to note your observations, test
steps and test results. A picture keeps you focused and often
saves duplicate effort.
3.
Record the front panel indications before changing anything.
This is an important part of fact gathering
4.
If you change anything, change only one thing at a time.
5.
Use the built-in test functions, especially the loopback tests and
record your results.
7.2
Loopback Tests
It is best to begin loopback testing at the remote terminal and work
toward the host. If all the loopbacks are successful, the data
communications equipment and the terminal are working correctly.
Put the SPL Drop multiplexer port in loopback and have someone type
alpha characters on the keyboard of the affected terminal. If the data
appears correctly on the screen, the port is working. Next loop the
associated port of the SRX host multiplexer. If data again appears
correctly, the communications link and the ports on both multiplexers
are working correctly. The problem then is with the host computer port
or the cable between the host computer and the multiplexer.
Loopbacks can be turned on and off from the Network Management port
of the SRX multiplexer. See paragraphs 5.4.3 and 5.4.4 for details. If a
NMP terminal is not available, drop multiplexer port loopback can be
enabled using a DIP switch on the multiplexer. Refer to Figure 1 and
paragraph 4.1.2.1 of the SPL Multidrop manual for switch location and
operation.
