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CHAPTER 1: INTRODUCTION
DEFINITY Communications System
7400B Data Module
Page 1-2
User’s Guide
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data metering option
programmable control characters
self-test at start-up
local and remote loopback tests
test duration timers
voice terminal powered by the PBX is not affected if ac power
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is removed from the 7400B Data Module
EXTERNAL FEATURES The external features of the front and rear panels of the 7400B Data
Module and the separate power supply unit are described in this section.
The data module has a removable access panel on top of the unit, which
is described further in the hardware installation section of Chapter 2,
“Installation.”
Front Panel
The front panel of the 7400B Data Module is shown in Figure 1-1, and
the 10 LEDs on the front panel are described in Table 1-1. In addition to
providing indications for normal operating modes, all of the LEDs are
also used as status indicators when the 7400B Data Module is first
powered on and the internal self-test is running.
Figure 1-1. Front Panel