Black Box MD1640A Modem User Manual


 
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SERIES II INTELLIGENT DATA/FAX MODEMS
The command to set the Modem Baud Rate is AT$MBn, where n can
be 300, 1200, 2400, 4800, 9600, 14,400,19,200, 28,800 or 33,600 bps as
listed below:
AT$MB300 = 300 bps
AT$MB1200 = 1200 bps
AT$MB2400 = 2400 bps
AT$MB4800 = 4800 bps
AT$MB9600 = 9600 bps
AT$MB14400 = 14400 bps
AT$MB19200 = 19200 bps
AT$MB28800 = 28800 bps
AT$MB33600 = 33600 bps
The factory default is 33600 bps.
Serial Port Baud Rate $SB
The $SB command presets the speed of the Series II Modem’s serial
(RS-232C) port, in both Originate and Answer modes. Speed
conversion allows you to set this serial port baud rate at a fixed speed
of up to 115,200 bps, regardless of the modem’s transmission speed
setting.
In order for this command to be effective, the modem’s Speed
Conversion feature must first be turned off with the $BA command.
When Baud Adjust is on, the Modem automatically adjusts its serial port
baud rate to match the speed of the computer or terminal it is connect-
ed to, as soon as it receives its first AT command. However, in many ap-
plications, such as automatic answer, the modem may not receive AT
commands, in which case it is very useful to be able to preset the serial
port baud rate with this $SB command.
In addition to setting the Modem’s serial port speed, this command also
sets the speed at which the modem issues Command mode responses.
The Modem will accept AT commands at any speed, regardless of the
speed preset by the $SB command. If the modem receives such a com-
mand at a speed that is different than the preset speed, the modem
switches its serial port baud rate to match the new AT command speed,
although the baud rate value stored by the $SB command remains the