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COURIER HIGH SPEED MODEMS
If you've performed an Analog Loopback and know your
modem is working properly, errors indicate a problem with
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either the phone connection or the remote modem.
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4.
Reset DIP switch 9 OFF unless you normally operate with it
ON. Issue an ATZ command to initiate the new switch
setting. Reset the modem to &M4 unless you've sent it the
A TZ reset command.
TESTING WITH REGISTER S16
Register S16 is a bit mapped register with the following bit
functions:
Bit Value
Function
0
1
Analog Loopback (AL)
1
2
Dial Test
2
4
Test Pattern
3
8
Remote Digital Loopback (RDL)
NOTE: Earlier USRobotics modems require bit 3 to be enabled
in order to grant RDL to a remote modem. The modem now
requires its default &T4 setting instead. To perform RDL with a
USRobotics modem that does not use the &T test repertoire, that
modem should be set to S16=8 before it can grant RDL testing.
ANALOG LOOPBACK (AL)-S 16= 1 D
As with the &T AL test, do not attempt this test under error
control. HST and Dual Standard modems should be tested at
2400 bps or lower, to avoid asymmetrical modulation at higher
speeds.
To use the modem's Test Pattern (Sl6, bit 2) instead of typing
your own data, see Test Pattern-516=4 later in this appendix.
1.
To initiate testing, type AT&MOS16=1D. The modem
disables error controt enters AL mode and sends a
CONNECT result code. The MR status light flashes.
2.
Type data to the modem for the modem to transmit, loop to
its receiver, and output to the screen. An alternative is to
use the Test Pattern, described later.
3.
End the test by not typing anything for one second, then
typing three pluses (
+++),
and waiting another second. This
F-8
Modem Testing
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