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DEFINITYEnterpriseCommunicationsServerandSystem75andSystem85
Terminals and Adjuncts Reference
555-015-201
Issue 11
December 1999
Data Modules
21-89DCIU Interface Units
21
DCIU Interface Units
The three interface units used in a DEFINITY Communications System Generic 2
and System 85 DCIU link are the 105A Isolating Data Interface (IDI), the 48250
Local Distribution Service Unit (LDSU), and the 2500-Series Data Service Unit
(DSU).
105A IDI
The IDI is a miniature connection unit for point to point, synchronous, full-duplex
operation between the DCIU and an external processor. The DCIU and the
external processor can be a maximum of 400 feet apart. Only one IDI is required
in each DCIU link.
Some of the features of the IDI are:
■ No options or adjustments
■ 0.3 through 19.2 kbps
■ Uses DCIU timing
■ Powered from the EIA control signals
48250 LDSU
The LDSU interfaces the System 85 DCIU with an external processor. It provides
the required isolation between the DCIU and the external processor. Two LDSUs
per external processors are required.
Each LDSU contains:
■ A transmitter with filtering and modulation — allows data transmission at
speeds from 2.4 kbps up to 19.2 kbps
■ A receiver with equalization, demodulation, clock recovery, and signal
presence detection — accepts incoming data from a 150 ohm line
■ A regulated DC power supply for the required DC voltage
■ An EIA RS-232-C interface
NOTE:
Each LDSU requires a 120-volt AC source.
2500-Series DSU
The 2500-Series DSU can be used as a Local Area Data Set for distances over
400 feet. Refer to the 2500-Series DSU section later in this chapter of the manual
for the information on the DSU.