US Robotics COURIER - Page 179

COURIER HIGH SPEED MODEMS
&T6
The test must be performed at 2400 bps or lower. If the remote
modem does not have the capability or is not set to respond, you
will get an ERROR result code.
As
with Analog Loopback, there are two Remote Digital
Loopback options.
If you select &T6, you send keyboard data to
the modem and verify it when it is returned over the phone lines
and to your screen. If you select &T7, the modem sends its
internal test
pattern and returns an error count to your screen.
NOTE: Both test options require 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. If
necessary, set the switch ON and then issue the ATZ command
to the modem to initiate the new switch setting.
1. Set the software to 2400 bps or lower. Set the modem to
&MO. If you wish, set the S18 timer.
Establish a connection with the remote modem. If you
haven't already done so, arrange with the remote user to
cooperate
with your testing and, if necessary, set the remote
modem to acknowledge the RDL request. For example,
older USRobotics high speed modems need to be set to
516=8.
2. Bring the Modem back to Command mode with the +++
escape code. Send it the AT&T6 command. The modem
enters RDL mode and the MR status light flashes.
3. Type a short message. It will be looped back to your modem
by the remote modem and to your screen for verification.
(The remote
user will not see your data.)
4. End the test. If you set Register 518 the modem
automatically ends the test when the test timeout is reached.
If you didn't set S18, type AT&TO 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 you issue an invalid
command, the modem sends an ERROR message.
Data errors indicate a
problem with the remote modem or
the phone link. If you have not performed analog loopback
F-6 Modem Testing
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