Справочник Пользователя для Multitech MT5600ZDXV

the same as the data received on your monitor.  If different data is

appearing on your monitor, your modem is probably causing the

problem, although it could also be your computer. If your modem passes

this test, but you are receiving errors while On-line, the remote modem

or the phone line could be at fault.

The Digital Loopback Test is an on-line test that loops data sent from one

modem across the phone line to another modem, then back to the first

modem.  See Figure 4-2. There are two ways to put a modem into Digital

Loopback mode:

1.  Locally or Manually, described here in section 4.2.

2.  Remotely or Automatically, see section 4.3.

Note: If you wish to abort any test in progress, enter AT&T0<CR>.

All loopback tests will operate at all speeds except 300 bps. Disable er-

ror correction (AT\N0&W0<CR>) before engaging in loopback tests.  In

this test the local modem is placed in Digital Loopback mode.  Data is

entered and transmitted from the remote modem (which is not in digital

loopback mode), sent across the phone line to the local modem and

looped back to the remote modem.

The test procedure is as follows:

1. Go into Terminal mode. Type AT and hit ENTER; you should get an OK

message.

2. Dial the remote modem by entering the Dial command and the phone

number, to establish On-line mode.

3. Type the Escape Sequence (+++) which brings your modem into

Command mode, while still maintaining the pseudo On-line mode with

the remote modem.

4. Type AT&T3 from the local PC and hit ENTER.  Once you receive an OK

message from your modem (if responses are enabled), the local modem

is placed in Digital Loopback mode.

5. Data is typed from the remote keyboard. For this test, typing multiple

upper case "U" characters is a good way to send an alternating test

pattern of ones and zeros. The data received by the local modem will

enter its analog receiver, be converted to digital data, be reconverted

into analog, and then looped through its transmitter back to the remote