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User Guide
134
Test procedure
1. Arrange to have &T6 set on the remote test modem.
2. Open your communications software and go into terminal mode.
Type AT and press ENTER; you should get an
OK
message. Type
AT\N and press ENTER to disable error correction.
3. Dial the remote modem and establish your online connection.
4. Type the escape sequence +++AT and press ENTER to bring your
modem into online command mode.
5. Type AT&T6 and press ENTER. The local modem responds to this
command by transmitting an unscrambled marking signal, which
causes the remote modem to place itself in digital loopback mode.
Then the local modem exits online command mode and enters data
mode.
6. Enter data from your keyboard. For this test, typing multiple upper-
case
U
characters is a good way to send an alternating test pattern
of binary ones and zeroes. Data received by the remote modem
enters its analog receiver, is converted to digital data, is reconverted
into analog, and then is transmitted back to your modem. Your mo-
dem passes this test if the data received on your monitor is the
same as the data entered from your keyboard.
7. To exit the test, type the escape sequence +++AT and press EN-
TER. This puts the modem in online command mode. The modem
should respond with an
OK
message. If you wish to stay on line with
the remote modem for normal data transmission, type AT&T and
press ENTER to exit the test, then type ATO and press ENTER to
return on line. If you wish to terminate the call, type ATH and press
ENTER to hang up.