AT&T MERLIN LEGEND Release 2.0 Equipment And Operations Manual page 222

Data Communications Support
Data Stations
A data station consists of data terminal equipment (DTE), such as a personal
computer (PC), data terminal, printer, optical scanner or video system, and data
communications equipment (DCE), such as an internal or external modem or an
external 7500B Data Module.
The DTE connects to the communications system via the DCE, which has
capabilities similar to a telephone. The DCE places the data call, maintains its
connection, and terminates the data call.
The DCE and DTE may have hardware and/or software options that can be set
for transferring and receiving data, such as parity and bit rate. Other options
may differ, depending on whether the transfer of data is synchronous or
asynchronous. See the DTE and DCE documentation for configuration
compatibility requirements, the options for transferring and receiving data, and
guidelines for changing options.
Data stations (PC-based or workstation-based) require a communications
software or terminal emulation package to transfer and receive data. The
communications setup for each data station depends on specific configuration
requirements and equipment limitations. Reference the communications
terminal emulation software documentation for instructions.
Data stations can be either analog or digital. Some analog data stations and all
digital data stations can include a telephone for users who need simultaneous
voice and data transmission.
Analog Data Station
An analog data station uses a modem as its DCE. The modem converts digital
signals from the DTE into analog signals. It transmits these signals as
continuously varying electrical voltages in the voice frequency band. It converts
incoming analog signals into digital signals, passing them to the DTE. Most
types of modems can be connected to the system. (See Chapter 2 for modem
hardware descriptions. )
From the standpoint of the communications switching system, the analog data
endpoint for an analog data station is the Tip/Ring (T/R) interface provided by
one of the following:
A General Purpose Adapter (GPA), connected to an analog multiline
telephone
A port on a T/R module (012T/R or 008 OPT)
A Multi-Function Module (MFM) adjunct on an MLX telephone
From a physical viewpoint, the connected modem provides a T/R analog signal
interface to the telephone network or switching system and an EIA RS-232
digital interface (or other type) to the data equipment.
5-4 Data Communications Configuration Overview
or