Specifications

7-1
Chapter 7
Troubleshooting
Overview
Malfunctions in your communications network can range in severity from an
unacceptably high error rate (more than one error per 100,000 bits) to a complete system
failure (no data transfer). To eliminate costly downtime, you need to act quickly when
any such malfunction occurs. The Excalibur Multirate DAP provides a full complement
of built-in diagnostic tests that help you to quickly and accurately isolate the source of the
problem. This chapter explains how to use these tests to effectively troubleshoot your
network.
Initial Checks
When a malfunction occurs, there are several checks you should perform before you
begin using the DAP's built-in diagnostic tests:
❏ Visually inspect each DAP. Check that the DAP is plugged in and that all cables
are in good condition and connected securely.
❏ Verify that the AC power outlet is providing the proper amount of voltage.
❏ Verify that each DAP's operating parameters are set correctly. Check for any
parameter changes that were made shortly before the malfunction began, as these
may have triggered the problem.
❏ Check the current status of the DTE interface signals. (See Chapter 6 for details.)
An abnormal signal status can point you towards the faulty component. For
example, a constantly low RTS signal points to a terminal problem while a
constantly low CTS signal points to either a network or a DAP problem.
Fault Isolation Strategy
A typical communications network consists of the following basic components: the local
and remote DTEs, the local and remote DAPs, and the interconnecting DDS lines. When
a malfunction occurs, the source of the problem can usually be isolated to one of these
components.
To isolate the defective component, you must systematically check the entire network.
The object is to eliminate components by verifying that they are operating properly. As
you verify that each component is operating properly, one component eventually stands
out as the source of the problem.