Black Box MD1641A, MD1640A manual Digital Loopback Test/V.54 Loop 2 Local/Manual

SERIES II INTELLIGENT DATA/FAX MODEMS

5.When testing is completed, you may exit Answer mode by entering an Escape Sequence (+++AT<CR> or <BREAK>AT<CR>), which returns the modem to Command mode.

6.Your modem passes this test if the data entered from your keyboard is 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.

8.3Digital Loopback Test/V.54 Loop 2 (Local/Manual)

In this test, your modem must be On-Line with another modem that can respond to a request for Digital Loopback, such as another Series II Modem. 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 8-2.

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

1.Locally or Manually, described here in section 8.3.

2.Remotely or Automatically, see section 8.4.

Note: The Digital Loopback Tests can only be used with the modem in Normal mode (error correction off).

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

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

type ATU3 and hit ENTER

Figure 8-2. Digital Loopback Test (local/manual)

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