TITLE
    PowerBook Fax/Data Modem: Disabling MNP Connections (7/94)
Article ID:
Created:
Modified: 		10125
4/29/92
7/21/94
TOPIC



    Which AT command switches MNP 5 on and off in the PowerBook Fax/Data Modem?

DISCUSSION


    There are several ways to disable MNP connections: Through '&Q', '%C' commands and through S register settings:

    From the Macintosh PowerBook Fax/Data Modem User's Guide, page 102
    ------------------------------------------------------------------
    &Qn Connection Mode, where if n equals (default is 5):

    0 Sets asynchronous mode with no error correction protocol.
    1-4 Returns ERROR.
    5 Error control mode. Instructs the modem to make a connection
    using the V.42/MNP. If remote modem does not offer V.42/MNP,
    the modem falls back to standard Asynchronous mode.

    From the Macintosh PowerBook Fax/Data Modem Developer's Guide, page 55
    ----------------------------------------------------------------------
    %Cn MNP 5 enable - Enables and disables MNP class 5 data compression during Reliable Mode connections. For use with MNP class 5, \L0 is mandatory, \J0 is recommended.

    %C0 Disables data compression. AT%C0 sets S46 to 136.
    %C1 Enables data compression (default). AT%C1 sets s46 to 138.

    From the Macintosh PowerBook Fax/Data Modem Developer's Guide, page 56
    ----------------------------------------------------------------------
    * \Jn BPS adjusts to DTE speed - After connecting, when in Direct Mode,
    the PowerBook and the Fax/Data Modem always adjust their data rate to the
    one used on the communication channel (between the Fax/Data Modem and the
    remote modem).

    When one of the three MNP modes is set, the PowerBook normally keeps the
    same data rate as used in the Command State and the modem, with the help
    of flow control, adjusts its speed and buffers data between the
    communication channel and the PowerBook. This can be modified with the \J
    command, which can disable that buffering possibility within an MNP mode.

    \J0 The modem adjusts its speed to the PowerBook; buffering is
    enabled (default).
    \J1 The modem and the PowerBook must adjust the speed to that of the
    communication channel without buffering, as in Direct Mode.

    * \L Service type - This command controls the MNP service type setting.

    \L0 Stream (default).
    \L1 Block; returns ERROR.

    From the Macintosh PowerBook Fax/Data Modem Developer's Guide, page 75
    ----------------------------------------------------------------------
    * S46: Error protocol selection V.42 and V.42bis (default is 138)

    0 Either LAP-M (V.42) or LAP-B (MNP).
    1 LAP-B only.
    2 LAP-M with adaptive data compression or LAP-B with adaptive
    compression.
    3 LAP-B with adaptive data compression.
    136 LAP-M (V.42) only.
    138 LAP-M with adaptive compression (V.42bis).

    All other codes return ERROR.

    * S48: Feature negotiation action V.42 and V.42bis (default is 7)

    0 Negotiation disabled in V.42 or V.42 bis modes only depending on
    S46.
    7 Negotiation enabled. Start with V.42 or V.42bis and fall back to
    MNP if required.
    128 Negotiation disabled. Force to MNP mode only.

    All other codes return ERROR.


    Article Change History:
    21 Jul 1994 - Changed access privileges to everyone.

    Support Information Services



Document Information
Product Area: Communications-Networking; Peripherals
Category: Modems & Fax Modems
Sub Category: PowerBook Express Modem

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