Owner`s manual

Chapter 6 - Testing Your Modem

5. Your modem passes this test if the data entered from your

keyboard are 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.

Note: All Loopback Tests operate at all speeds except 300 bps; and

disable error correction (&E0&W0<cr>) before engaging in loopback

tests.

Digital Loopback Test/V.54 Loop 2 (Local/Manual)

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 6-2.

There are two ways to put a modem into Digital Loopback mode.

1. Locally or Manually, described here in section 6.2.

2. Remotely or Automatically, see section 6.3.

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

and hit ENTER; you should get

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 (

+++AT<CR>

)

which brings your modem into Command mode, while still

maintaining the pseudo On-line mode with the remote modem.

4. Type

ATU3

from the local PC and hit ENTER. Once you receive

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

local modem is placed in Digital Loopback mode.