Functions
i-modul Modem 144/56k
6.5
Error Correction
The i-modul Modem 144/56k 3.0 basic masters the V.42 error correction protocol
including the Microcom Networking Protocol Levels 2/3/4 (MNP2, MNP3, MNP4)
and the data throughput optimization MNP10. The V.42 error correction includes
the protocols LAPM (Link Access Procedure for Modem) and MNP4. LAPM is the
preferred error correction. MNP 4 is supported to maintain the compatibility with
other MNP modems. Both methods determine frames to transfer net data and use
CRC (Cyclic Redundancy Check) check sums for error tests. In V.42, there is the
option to have the modem identify if the partner is a V.42 modem, a MNP modem,
or a modem without error correction. The modem can then autonomously adjust to
the partner.
As default, the automatic selection of V.42LAPM or MNP4 or no correction is set.
Configuration with AT commands
To define the type of error correction, use
the command:
AT\N<n>
To set V.42LAP-M or MNP4 error correction
exclusively, use:
AT\N2
Use the following command for the i-modul
Modem 144/56k 3.0 basic to automatically
select V.42LAP-M, MNP4, or an error-
corrected connection:
AT\N3
To set V.42LAP-M error correction
exclusively, use:
AT\N4
For the buffered mode without error
correction, use:
AT\N0
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