103
MINIMODEM USB
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 uppercase 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 modem
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 ENTER. 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.
