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7 Diagnostic Facilities
7.1 Introduction
Operational problems may be caused by any of the following:
Faulty local, or remote, DTE.
Faulty local, or remote, modem.
Faulty telephone line.
Communications software set up incorrectly.
The modem can run the following diagnostic tests to help locate the source
of operational problems, when in V.22bis or V.22 modes:
Local Analogue Loopback, with or without self-test (Section 7.2.1).
Remote Digital Loopback, with or without self-test (Section 7.2.2).
The self-test feature allows a pattern generator to send test sequences
through the modem. These are error-checked and, when the test is
terminated, the modem responds with the number of errors encountered.
Tests can be activated by:
The front panel buttons (Section 7.3).
AT commands (Section 7.4).
Signals in the DTE interface (Section 7.5).
Sequence of Testing
The Local Analogue Loopback test should always be activated first, as this
test checks the connection between the local DTE and the local modem's
modulator/demodulator.
The Remote Digital Loopback test should be activated next. This test
checks the connection from the local DTE, over the telephone line, to the
remote modem's modulator/demodulator.
Analysis of each test result should indicate the source of possible faults.
X460-306851 Issue 1 7-1 Rev.0