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Chapter 5 - Testing the Modem
5.4 Local Analog Loopback Test (Synchronous Mode)
To initiate the Local Analog Loopback Test, with the modem in
Synchronous mode:
1. Enter AT&M1U. This first switches your modem from asynchronous to
synchronous mode, and places it into the Analog Loopback/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, pull out and then reinsert modem card in rack cage.
Then type AT&M1U1 and hit ENTER to place the modem in Analog
Loopback mode, in the Answer mode. Then repeat step 2.
Figure 5-4. Local Analog Loopback Test (Syncronous Mode)
Digital
Analog
Computer or Terminal
Local MultiModem
UUUU