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&T7 Remote digital loopback with self-test. This test
verifies the operation of two connected modems and
the phone channel. It sends an internal test pattern
through the loop and returns a numeric message
that indicates the number of errors that were
counted during the test period. (See &T6.)
For example:
1.
Your modem should be on-hook and in
command mode. Type AT \N0 <Enter>.
2.
Type AT S18=10 <Enter>. This specifies a test
period of 10 seconds.
3.
Establish a connection with the remote
modem by typing AT Dnnn-nnnn <Enter>.
Wait for the CONNECT message.
4.
Issue the escape sequence to put the modem
back into command mode (type +++ without
pressing <Enter>). When you see the OK
message, your modem is in command mode.
5.
Issue the command AT &T7 <Enter>. This
initiates the remote digital loopback with
self-test. Note that the remote modem must
support CCITT V.54 and must be prepared
to accept the request for this test. (See &T4.)
6.
The test will end automatically after 10
seconds. The number of errors that were
counted are displayed on your screen at the
end of the test. 000 means that there were no
errors. 255 means that there were 255 or more
errors.
7.
When your testing is complete, hang up the
line and return your modem to its original
state by typing ATHZ <Enter>.
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