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
0.3 through 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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