Error Correction; Data Compression - INSYS 56k Small INT 2.0 Manual Manual

Functions
12.6

Error correction

The INSYS Modem 56k Small INT 2.0 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 meth-
ods 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 HSComm
Select the type of data flow control or switch it off completely on the tab Mo-
dem in the panel "Error correction" (Page 27, Figure 5: HSComm Modem - Tab
Modem, Position 25).
Configuration with AT commands
To define the type of error correction, use the
command:
To set V.42LAP-M or MNP4 error correction
exclusively, use:
Use the following command for the INSYS
Modem 56k Small INT 2.0 to automatically
select V.42LAP-M, MNP4, or an error-corrected
connection:
To set V.42LAP-M error correction exclusively,
use:
For the buffered mode without error correc-
tion, use:
12.7

Data Compression

The INSYS Modem 56k Small INT 2.0 supports various data compression types. During
the connection setup, it will automatically detect the type of data compression used by
the remote terminal, or it is set to a certain type of data compression. Data compression
is only available for error corrected connections. To be able to use data compression,
both sides (sender and recipient) must be able to at least recognize and support the
same data compression mode.
The default setting is the automatic selection of MNP5 and V42.bis and V.44 data com-
pression (AT%C3).
34
INSYS Modem 56k Small INT 2.0
AT\N<n>
AT\N2
AT\N3
AT\N4
AT\N0