3Com 56K manual Using AT&T1

Testing the Business Modem using AT&Tn 14-3

Analog Loopback Local loopback testing checks the operation of the Business Modem Testing transmitter and receiver.

Using AT&T1

1Send AT&M0&N3S14.0=0 to prepare the modem for testing.

This command disables error control, fixes the connection rate at 2400

bps, and makes the modem return to command mode when you type

+++.

2Send AT&T1 to the modem so it enters analog loopback mode. The MR status light flashes.

3It will be looped back by your modem's transmitter for verification on your screen.

4When the test is completed, send +++ and then AT&T0 to end the test.

Alternatively, you can end the test by sending ATH, or ATZ. Be careful, though, because ATZ resets the modem in addition to ending the test.

In either case, the modem responds with OK. If the modem sends an ERROR message, you have issued an invalid command.

5Send AT&M4, unless you used a reset command (ATZ).

If the Business Modem is in online mode that is still connected to a remote modem, and you send AT&T1 or AT&T8, it drops the call, enters analog loopback mode, sends a CONNECT result and waits for loopback characters.

Stopping a Test To stop a test, send AT&T0 to the modem, or set Register S18 to a (AT&T0, ATS18) specified number of seconds (for example, ATS18=10). When the 10

seconds are up, the modem will stop the test automatically and return to Command Mode. Send ATH to the modem to hang up, or send ATZ to hang up and reset the modem to its defaults.