Multi-Tech Systems MT2834MR6 manual Baud Adjust $BA, Modem Baud Rate $MB

Chapter 5 - Error Correction, Data Compression, and Speed Conversion

5.12.1 Baud Adjust ($BA)

In typical operations, the MT2834MR6 will do one of two things regarding speed. It will automatically match the speed of its RS-232 interface and phone line transmissions to that of the terminal or computer to which it is connected as soon as it receives its first AT command. Or, in autoanswer mode, it will match its RS-232 and transmission speeds to that of the originating modem that called it. This is typical of many dial-up modems, and it is referred to variously as auto-speedor baud adjust. Multi-Tech uses the term baud adjust.

When you enable speed conversion, the modem does not adjust its speed at the RS-232 serial port, even if the modem does adjust its line transmission speed. To turn baud adjust off and speed conversion on, type AT$BA0 (where the 0 is a zero).

Note: Even though baud adjust sounds like it should mean the same thing as speed conversion, it actually means the opposite.

a.Turning baud adjust off turns speed conversion on.

b.Turning baud adjust on turns speed conversion off.

To turn baud adjust on and speed conversion off, type AT$BA1 and press ENTER. The modem will now match its RS-232 speed to that of the computer, and will adjust its speed to any changes in the computer’s speed in the originate mode, or to the speed of the originating modem when it’s in the answer mode. With baud adjust on, the speed at which the modem communicates over the phone line is always the same as the speed at which it communicates via its RS-232 serial port.

5.12.2 Modem Baud Rate ($MB)

The $MB command presets the MT2834MR6’s transmission rate for originate operations, i.e., the speed of the modem’s transmissions over the telephone lines when originating a call. With speed conversion, this transmission speed can be a different rate than the serial port speed.

When the MT2834MR6 receives a call from another modem, it automatically switches its phone line transmission rate to match the calling modem. However, if the MT2834MR6 originates a call to another modem that is unable to connect at the speed of the MT2834MR6, the MT2834MR6 will automatically drop to a lower speed in an attempt to match the speed of that modem. For example, if the MT2834MR6 is set for 28,800 bps and calls another modem that has a top speed of 9600 bps, it will drop to 9600 bps.

When baud adjust is on ($BA1), speed conversion is off, as we discussed earlier. In that case, the $MB command is ignored, since it is part of speed conversion.

To set the Modem Baud Rate, type AT$MBn, where n is the desired rate.

AT$MB75	ITU-T V.23			AT$MB300	300 bps
AT$MB1200	1200	bps		AT$MB2400	2400	bps
AT$MB4800	4800	bps		AT$MB9600	9600	bps
AT$MB14400	14,400		bps	AT$MB16800	16,800		bps
AT$MB19200	19,200		bps	AT$MB28800	28,800		bps
AT$MB33600	33,600		bps (factory default)

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