General DataComm 060A027-001, Installation & Operation Manual

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Operation Synchronous Operation
060R122-000 SpectraComm Dual V.34 Modem 3-33
Issue 15 Installation and Operation
V.13 Synchronous Mode
The
\M1
command selects the Synchronous V.13 Protocol. V.13 mode 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.
The RTS/DCD signaling can be configured for either bi-directional or unidirectional control by the
&E
command. The following DTE data rates are available (
\T
n command) when the modem
operates in V.13 synchronous mode:
Synchronous Compression Mode
The
\M2
command selects the Synchronous Compression Protocol. The modem can compress
synchronous DTE data framed in HDLC/SDLC format, with a maximum frame length of 2048
bytes. Synchronous compression supports the following DTE data rates (
\T
n command):
Two techniques for modem-to-DTE hardware flow control are available for use with synchronous
compression. Both require that the modem be configured for internal timing (see below). Flow
control for synchronous compression can be accomplished by:
• Clock Stopping (
\Q5
) in which the modem prevents buffer overflow by sharply reducing the
frequency of the transmit clock signal it outputs to the DTE.
• Clock Throttling (
\Q6
) in which the modem prevents buffer overflow by varying the rate at
which it outputs the transmit clock signal to the DTE
28,800 bps 26,400 bps 24,000 bps 21,600 bps 19,200 bps
16,800 bps 14,400 bps 12,000 bps 9600 bps 7200 bps
4800 bps 2400 bps 1200 bps
128,000 bps 115,200 bps 112,000 bps 96,000 bps 76,800s
72,000 bps 64,000 bps 57,600 bps 56,000 bps 48,000 bps
38,400 bps 32,000 bps 28,800 bps 26,400 bps 24,000 bps
21,600 bps 19,200 bps
Note
Synchronous Compression is an optional feature that is not included in all modems. To check the presence
of the feature in your modem, use AT command
I4
to display a list of information concerning the mo-
dem. Sync Compression On/Off is included in that list.
Note
Synchronous compression mode will not be available in modems configured for AES Encryption.