Digital Loopback Test/V.54 Loop (Rem/Auto) - Multitech MMH900 User Manual

I.4

Digital Loopback Test/V.54 Loop (Rem/Auto)

In this test, your modem must be On-line with another modem set up to
respond to a request for Digital Loopback, such as another MMH2834.
With the MMH2834, this ability to respond is controlled by the &T
command. AT&T4 enables the response to Digital Loopback Test
(remote/automatic). AT&T5 disables the response. The modem defaults
to disable on power up, so this must be changed on the remote modem
before the modem will respond to a request for the Digital Loopback Test
(remote/automatic).
Initiate the Digital Loopback Test (remote/automatic) with the ATU2
command which automatically places the remote modem in digital
loopback mode. Data from your computer or terminal are transmitted
through your modem, and over the phone line to the remote modem,
where they are then looped back to your modem. See Figure I-3.
Local MultiModem
Computer or Terminal
UUUUU
UUUUU
Digital
Type AT in Terminal mode; hit
ENTER; dial remote modem;
establish On-line mode; enter
escape sequence; type
ATU2; hit ENTER
Figure I-3. Digital Loopback Test (remote/automatic)
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.
Note: The &T4 command must be set on the remote modem to run this
test.
3. Type the Escape Sequence (+++AT<CR> or <BREAK>AT<CR>)
which brings your modem into Command mode, while still
maintaining the connection with the remote modem.
Appendix I - Testing Your MMH 2834
Remote MultiModem
Analog Analog Digital
Computer or Terminal
153