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COURIER HIGH SPEED MODEMS
Modem Testing H-5
NOTE: This test requires the modem to establish a connection
and return to online-command mode in response to the +++
escape code. DIP switch 9 must be set ON so that the modem
does not hang up on receipt of the escape code. After you
change the switch, issue ATZ to the modem to initiate the new
setting.
As with AL testing, HST and Dual Standard modems should be
tested at 2400 bps or lower.
1. Set the modem to &M0, to disable error control. HST and
Dual Standard modems should be set to 2400 bps or lower
to avoid asymmetrical modulation at higher speeds.
Establish a connection with the remote modem.
2. Bring the modem back to Command mode with the +++
escape code. Then send it the AT&T3 command. The
modem enters DL mode and the MR status light flashes.
3. The remote user should type a short message. It will be
looped back by your modem's transmitter for verification
on the remote screen. You will not see the message or any
other data.
4. When the remote user has completed the test, issue the
AT&T0 command to end the test. Or send either ATH or
the command that resets the modem, ATZ. The latter two
commands end the test and hang up the modem. The
modem responds OK. If the modem sends an ERROR
message, you have issued an invalid command.
5. Reset DIP switch 9 OFF if you normally use the factory
default. Reset the modem to &M4 unless you used the reset
command, ATZ.
&T4, &T5
The &T4 option causes the modem to grant a remote modem's
request for a Remote Digital Loopback test.
The &T5 option cancels &T4, and the modem fails to recognize
such a request. This is the default so that your modem isn't
subject to another user calling and tying up your modem
without your permission.