Black Box MD1641A, MD1640A manual Serial Port Baud Rate $SB

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$MB300 AT$MB1200 AT$MB2400 AT$MB4800 AT$MB9600 AT$MB14400 AT$MB19200 AT$MB28800 AT$MB33600

=300 bps

=1200 bps

=2400 bps

=4800 bps

=9600 bps

=14400 bps

=19200 bps

=28800 bps

=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

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