Black Box MD1641A Manuale Utente

To initiate the Local Analog Loopback Test, with the modem in
Synchronous mode:

1.

Enter 

. 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 (

or 

) which brings your modem into Command

mode, while still maintaining the connection. Then type

and hit ENTER to place the modem in Analog

Loopback mode, in the Answer mode. Then repeat step 2. 

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,

Type ATU0 or ATU1; hit ENTER

Computer or

Terminal

Local Series II Modem

digital

analog