AT&T System 85 manual Dciu Interface Units, 105A Isolating Data Interface IDI, Series DSU

DCIU Interface Units

DCIU Interface Units

The three interface units used in a DEFINITY G2 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 Isolating Data Interface (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

0.3through 19.2 kbps Uses DCIU timing

Powered from the EIA control signals

48250 Local Distribution Service Unit

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 detec- tionaccepts incoming data from a 150 ohm line

A regulated DC power supply for the required DC voltage

An EIA RS-232-C interface

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 of this document under the DATA MODULE tab for the informa- tion on the DSU.

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