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SERIES II INTELLIGENT DATA/FAX MODEMS
To initiate the Local Analog Loopback Test, with the modem in
Synchronous mode:
1. Enter AT&M1U. This first switches your modem form asynchro-
nous to synchronous mode, and places it into the Analog Loop-
back/Originate mode. The modem is now out of the Command
mode and in the pseudo On-Line mode.
2. Once you receive a connect message (if responses are enabled), 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
ones and zeros.
3. For a more complete test, you should also test the modem in
Answer mode. To do this, Type the Escape Sequence (+++AT<CR>
or <BREAK>AT<CR>) which brings your modem into Command
mode, while still maintaining the connection. Then type
AT&M1U1 and hit ENTER to place the modem in Analog
Loopback mode, in the Answer mode. Then repeat step 2.
Figure 8-5. Synchronous Mode Local Analog Loopback Test
8.8 Digital Loopback Test (Local/Manual)
(Synchronous Mode)
This test must be run when you have a data connection with another
modem. If a Local Analog Loopback Test resulted in errors, and this
test passes without errors, then the problem exists in your computer-to-
modem connection. In Digital Loopback Test (local/manual) mode,
UUUUU
UUUUU
Type ATU0 or ATU1; hit ENTER
Computer or
Terminal
Local Series II Modem
digital
analog