Remote Digital Loopback L2 - &T6
Remote digital loopback verifies the operation of both modems, the local
computer, and the telephone circuit, by commanding the remote modem to loop
data sent to the remote system back to the local modem.
Note: This test may be performed with a V.22 or V.22bis connection
and &Q0 mode selected.
Before initiating remote digital loopback, establish a connection with a
remote modem. Then, enter the command state and issue the &T6 command to
begin the test.
Type a few sentences; they are looped back to the local computer without
appearing on the remote screen. If the modem echoes your keyboard input
to the screen as you typed it, the modem is operating correctly. If the
received data does not match what you typed, one of the modems or the local
communication link is not functioning properly. To end the test, enter the
command state and issue the &T0 command.
Note: The local modem requests a digital loopback with the remote
modem through a special ITU-T standard handshake sequence. The remote modem
automatically acknowledges the request if it has been conditioned to do
so with the &T4 command. (See &T4 and &T5
commands) If the remote modem is not Hayes-compatible, it may not permit
this test to be executed from the local modem (response is ERROR). However,
if the remote user can put the modem into local digital loopback or an equivalent
state, the test can be performed from the local modem.
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