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Models MT5600ZDX & ZDXV
Local Analog Loopback Test/V.54 Loop 3
In this test, data from your computer or terminal is sent to your modem's
transmitter, converted into analog form, looped back to the receiver,
converted into digital form and then received back at your monitor for
verification. No connection to the phone line is required. See Figure 4-1.
Figure 4-1. Local Analog Loopback Test
The test procedure is as follows:
1. Connect the modem to your computer. With your communication
software, set the desired baud rate.
2. Type AT&T1 and hit ENTER. This places your modem in Analog
Loopback mode, in the Originate mode. The modem is now out of the
Command mode and in a pseudo On-Line mode.
3. 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.
4. For a more complete test, you should also test the modem in Answer
mode. To do this, you must escape from Originate mode by entering
an Escape Sequence (+++) . Then type AT&T1 and hit ENTER to place
the modem in Analog Loopback mode, in the Answer mode. Then repeat
step 3.
5. Your modem passes this test if the data entered from your keyboard are