3Com Courier, Reference

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10-2 C
HAPTER
10: C
ONTROLLING DATA RATES
Your software may use terms such as locked serial port (fixed rate) or
autobaud (variable rate).
The serial port rate MUST be equal to or higher than the Connection rate
(&Nn).
To allow your modem
Set the serial port
rate as
Command
To change its serial port rate to match the
connection rate. Variable
AT&B0
To always communicate with an attached
device at the rate at which you have set
the terminal or software, regardless of
the connection rate. Fixed
AT&B1
(Default)
For the greatest throughput, set the serial
port to 230400, 115200, 57600, or
38400 bps for high-speed calls, and to at
least 9600 bps for 2400-bps calls.
To shift its serial port rate to a rate that
you specify using your communications
software (for example, 38.4 Kbps) when
the Courier V.Everything modem
connects in ARQ mode.
If the connection is not under error
control, the Courier V.Everything modem
behaves as if it was set to &B0 and
switches its serial port rates to match the
connection rate of each call.
Fixed for ARQ calls
and
AT&B2
To implement this feature, first set your
software to the desired rate. Then send
AT&B2&W
to the modem.
The Courier V.Everything modem stores
the rate of the command in NVRA
along with the current settings. The
Courier V.Everything mode
checks
NVRAM for the specified serial port rate
each time it makes an ARQ connection.
When saving subsequent configurations
to NVRAM, be sure your software is set to
your selected serial port rate so the
correct rate is maintained.
Variable for non-ARQ calls when
answering only.
See Chapter 13,
Handshaking, Data
Compression, and Error Control, for
more information about ARQ