Multitech MMH900 User Manual page 178

Appendix J - Internal MMH2834 Composite Link Modem Commands
Enable/Disable In Auto-Reliable mode, the modem is given four seconds to
Auto-Reliable establish a Reliable connection. If a single CARRIAGE RETURN
Fallback Character is received from the remote modem during this four second
$F period, the Auto-Reliable modem assumes that the remote
modem is not in Reliable mode and drops to Normal mode. The
CARRIAGE RETURN is the only character which causes the
modem to drop to Normal mode. Any other character will either
be buffered or discarded.
The $F command can be used to disable this fallback-to-
Normal-due-to-CARRIAGE-RETURN feature.
The Auto-Reliable fallback character ($F) and Auto Reliable
buffering ($A) commands can be used together to cause the
modem to buffer all data received up until the CARRIAGE
RETURN, and then drop to Normal mode. All data received will
then be output following the CONNECT message.
AT$F0 = Do not fall back to Normal if CARRIAGE RETURN received.
AT$F1 = Fall back to Normal mode if CARRIAGE RETURN received.
The factory default is $F1.
Retransmit Count If errors are received during a Reliable connection, the modem
re-sends the block of data which contained an error. With the
$R $R0 command, if another error occurs, the block will be re-sent
again. The modem counts the number of times that a data block
is re-sent. If the same block of data is resent 12 times and still has
not been received properly, the modem assumes that the
transmission line is unsuitable for transmission, and abort the
connection.
This retransmit counter is disabled by the $R1 command. When
the retransmit counter is disabled, the modem keeps trying to
send data and will not abort, no matter how many times the same
block is resent.
AT$R0 = Disconnect if retransmit count is exceeded.
AT$R1 = Do not disconnect due to retransmits.
The factory default setting is $R0.
V.42 Error At 300 bps, error correction is not typically used. $E1 lets the
Correction/300bps lets the MMH2834 function at 300 bps in either Normal (&E0),
Auto-Reliable (&E1) or Reliable (&E2) mode. $E0 which is the
$E the MMH2834's default, disables 300 bps/V.42 error correction
altogether.
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