Black Box MD1641A, MD1640A manual Digital Loopback Test/V.54 Loop 2 Remote/Automatic

SERIES II INTELLIGENT DATA/FAX MODEMS

8.4Digital Loopback Test/V.54 Loop 2 (Remote/Automatic)

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 Series II Modem. With the Modem, 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 8-3.

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.

Computer									Computer
or Terminal									or Terminal
			Local Series II			Remote Series II
				Modem			Modem
	UUUUU
	UUUUU	digital				analog
					analog			digital

Type AT in Terminal mode; hit ENTER; dial remote modem; establish On-line mode; enter escape sequence; type ATU2 and hit ENTER

Figure 8-3. Digital Loopback Test (remote/automatic)

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