Speed Conversion Commands - Multitech CommPlete MT3334HD8 User Manual

$Rn Retransmit Count
n = 0 or 1
Default: $R0
If errors are received during a reliable connection, the modem re-sends the block of data that contained an
error. If another error occurs, it re-sends the block again. The modem counts the number of times that a
data block is re-sent.
$R0 causes the modem to disconnect if the same block of data is re-sent 12 times without being received
properly, on the assumption that the line is unsuitable for transmission.
$R1 causes the modem to disable the retransmit counter, so that the modem keeps trying to send data and
will not abort, no matter how many times the same block is resent. Type AT$R0 to disconnect the modem
if all attempts to re-send the block fail.

Speed Conversion Commands

Speed conversion allows the MT3334HD8 to communicate at a fixed speed through the serial port while
communicating at an independent speed over the online communications link.
Speed conversion is necessary for data compression, since data compression requires data to be sent from
the computer to the modem at a rate up to four times faster than the modem's transmission speed.
Speed conversion is also useful for an auto answer modem connected to a computer that does not have auto
baud capability, since the computer must be set at a fixed baud rate regardless of the speed at which the
modem communicates over the phone line.
$BAn Baud Adjust
n = 0 or 1
Default: $BA0
Even though the term "baud adjust" sounds like it should mean the same thing as "speed conversion," it
actually means the opposite. Turning baud adjust off turns speed conversion on; turning baud adjust on
turns speed conversion off.
When baud adjust is on, the modem matches its RS-232 serial port speed to any changes in the computer's
serial port speed in originate mode, or to the speed of the originating modem when it's in 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.
When speed conversion is on, the modem does not adjust its speed at the serial port to match its
transmission speed. Serial port speed and transmission speed can therefore be set independently. Speed
conversion is necessary for a high speed modem that is connected to a limited speed serial port.
$BA0 turns baud adjust off and speed conversion on.
$BA1 turns baud adjust on and speed conversion off.
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