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Command:
Result code:
Here, the test timer is disabled and the modem sets up an internal analog loop as shown in Figure 4-1.
When the loopback is established, the modem goes on-line and the test message (any character you type)
is looped back on the screen for verification. Finally, +++ returns the modem to the command state and
&T0 ends the test and breaks the internal analog loop.
The following command sequence is the same as the previous one except that the test timer is set to 60
seconds. At the end of the test time, the timer expires, the test ends, and the test result is reported.
Example 2 - test timer enabled
Command:
Result:
Test message:
Escape:
Result code:
4.2 Local Analog Loopback with Self-Test
The local analog loopback with self-test checks the integrity of the local modem. In this test, an internally
generated data pattern of alternate binary ones and zeros (reversals) at the selected bit rate is looped
through the internal analog loop inside the local modem to an internal error counter as shown in Figure 4-
2. An error count of 255 indicates that 255 or more errors were detected.
Example-the test timer is disabled and 12 errors are found during the test
Command:
Result:
AT&T0 <CR> (end the test)
OK
AT&Q0<CR>
ATS18=60&T1<CR>
CONNECT 56000
THE QUICK BROWN FOX JUMPS OVER
THE LAZY DOG 1234567890
+++
OK
AT&Q0<CR>
ATS18=0&T8<CR>
OK
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