US Robotics COURIER - High Speed;Low Speed Protocol Explained

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COURIER HIGH SPEED MODEMS
HIGH SPEED/LOW SPEED PROTOCOL
OVERVIEW
This appendix explains how an answering Courier modem
switches its link rate to match the rate of a calling modem. It
may be of help also to those users who want to try programming
their computers to switch bit rates to match the Courier's
connection rate. The material here applies only when the
modem is set for variable rates at both the DTE (computer) and
link interfaces, &BO and &NO, respectively.
In both Originate and Answer modes, if the link rate is set to
&NO, the Courier negotiates with the remote modem to connect
at the highest possible rate. In addition, if the modem is set to
Extended or Advanced result codes (Xl or higher) it signals the
DTE with one of the following result codes or the optional result
codes selected with the &An command.
CONNECT (300 bps)
CONNECT 1200 (1200 bps)
CONNECT 2400 (2400 bps)
CONNECT 4800
(4800
bps)
CONNECT 7200
(7200
bps)
CONNECT 9600 (9600 bps)
CONNECT 12000 (12,000 bps)
CONNECT 14400 (14,400 bps)
CONNECT 16800 (16,800 bps-HST-to-HST
connections only)
The modem sends the result code at its previous rate. Then it
switches to the new connection rate.
If your computer doesn't switch rates and you want to program
it to do so, use the example on the next page as a guide. It
demonstrates the occurrence of the CONNECT codes in the
connection sequence, so that recognition of the codes can be used
to switch the computer. The example uses a sequence of
incoming calls, but the codes apply to Originate mode
connections as well.
The example assumes the following settings:
Fax and Other Operations E-13