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Synchronous Modes
This section explains the use of your modem in synchronous modes. A dumb mode or manual
mode allows some of the functions of your modem to be accessed via the front panel switches.
Some of the information in this section assumes you have read the Getting Started Section.
Your modem offers two synchronous modes, conforming to the Hayes modem synchronous
modes 1 and 2. These modes allow synchronous communication over two-wire PSTN or leased
lines when connected to asynchronous/ synchronous computers or dedicated synchronous
terminals.
Synchronous Operation
Your modem supports two synchronous modes. Mode 1 allows operation with computers
which support asynchronous and synchronous communication on a single RS-232 port. Mode 2
allows your modem to be operated with dedicated synchronous terminals.
Although your modem can only operate over a single two-wire connection, it will still perform
full-duplex synchronous communication. Half-duplex operation could be simulated by
controlling the state of the RTS and CTS signals.
Terminal Speeds
Your synchronous terminal or host should use the clock signals provided by the modem to
synchronise transmit and receive data. The clock speed will represent the actual connection
speed of the modem.
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When synchronous mode is selected, your modem cannot operate in constant
speed mode or use the error correction or data compression facilities of the
modem. Only variable speed mode is available in synchronous connections (this
refers to the modem’s terminal speed).
Line Speeds
Your modem supports a number of synchronous line speeds.
When operating in synchronous mode, your modem should always be configured with a locked,
non-auto-ranging B setting (this refers to modem line speed).
For V.34 or V.FC, the B setting only sets the maximum speed. The modem will automatically
determine the highest usable speed for the line.