General DataComm 060A027-001, Installation & Operation Manual

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Operation Asynchronous Operation
3-30 SpectraComm Dual V.34 Modem 060R122-000
Installation and Operation Issue 15
Non-Error Correcting Modes
The modem also employs the following non-error correcting modes, described below. Like the
MNP and V.42 protocols, these modes are configured using the
\N
command.
• wire mode
• direct V.14 asynchronous mode
• V.13 mode
Wire Mode
Wire mode (
\N0
) is used to communicate with standard, non-error correcting modems. The modem
will fall back to wire mode if it fails in an attempt to negotiate an auto-reliable link with the remote
modem. Error correction is not active in wire mode. Wire mode provides data buffering so that the
modem's DTE and VF interfaces can operate at different speeds. For example, the local DTE can
exchange data with the local modem at 19,200 bps while the modem communicates at 2400 bps
with the remote modem. To do this, however, the local terminal emulation software must allow its
autobaud feature to be turned off and allow flow control.
Direct V.14 Asynchronous Mode
In direct V.14 mode (
\N1
) there is no error correction, data compression, or data buffering. The
modem's DTE data rate and VF line speed must be set to the same value. If, for example, the link
between the local modem and the remote modem operates at 9600 bps, then the local DTE must
exchange data with the local modem at 9600 bps.
V.13 Mode
V.13 mode (
\N6
) is a simulated controlled carrier mode designed for polling applications. It uses
the ITU-T V.13 RTS/DCD signaling method to control the remote modem's DCD lead via the local
modem's RTS lead. It can be used for both synchronous and asynchronous data. The RTS/DCD
signaling can be configured for either bi-directional or unidirectional control by the
&E
command.
Table 3-4 Enabling Error Correction/Data Compression
To Enable: Use AT Commands:
V.42 Auto Reliable
\N3
and
%C0
V.42
bis
\N3
and
%C1
Wire or MNP 2-5 or V.42 bis
\N3
and
%C1
V.42 (LAPM) and V.42 bis only
\N4 and %C1
V.42 only
\N4
and
%C0
MNP Level 2-5 only
\N2
and
%C1
MNP Level 2-4 only
\N2
and
%C0
V.42, V.42
bis or MNP 2-5 only
\N5
and
%C1
V.42 or MNP 2-4 only
\N5
and
%C0
Wire (speed buffering), no data compression, no error correction
\N0 and %C0
Direct (no speed buffering), no data compression, no error correction
\N1
and
%C0