AT&T System 85 manual 7400B and 7400B Plus Data Module, Block Diagram of the 7400B Interface

7400B and 7400B Plus Data Module

DATA

TERMINAL

RS-232C	7400B or	DCP
	7400B PLUS

DIGITAL

VOICE

TERMINAL

DIGITAL SWITCH

DIGITAL

LINE

PORT

FIGURE 5-2. Block Diagram of the 7400B Interface

Physical Description

Dimensions

Note: The following measurements for the 7400B and 7400B Plus data module are approx- imate.

Width = 7 inches

Depth (front and rear) = 8 3/4 inches

Height = 1 3/4 inches

Lights

POWER/TEST light

The red POWER/TEST light goes on when AC power is supplied to the 7400B or 7400B Plus data module and flashes during all tests. This light, together with the DATA light, also flashes if there is a DCP line problem.

DATA light

The green DATA light goes on during a data call. This light, together with the POWER/TEST light, flashes if there is a DCP line problem.

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