6.3 Using the Test Timer
S18
Register S18 determines all selftest duration’s, and the modem
automatically ends tests and returns to command state when the S18
time expires. The S18 default is zero, to disable the test timer.
6.4 Ending a Test
&T0
A test can be terminated at any time by issuing the escape sequence,
causing the modem to enter command state and then issue AT&T0.
Any command following &T0 in a command line is ignored.
6.5 Local Analog Loopback Test
&T1
The local loopback test (LAL) verifies the path between the computer
and the modem. Everything you type on the keyboard during the test
will be echoed by the modem back to the computer.
To initialize an LAL test, issue AT&T1. The test begins after the
modem responds with a carriage return and a line feed. Type any
character string on the keyboard, and the string should appear correctly
on the screen. If errors are found, the modem, computer or path might
be at fault.
Telephone Line
Receiver
Transmitter
Analog Loop
Local Computer
Figure 6-1 Local Digital Loopback Test
6.6 Local Digital Loopback Test
&T3
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