Control Unit - AT&T MERLIN LEGEND Installation & Maintenance Manual

System Description

Control Unit

The control unit (CU) connects central office (CO) lines with
telephones and adjuncts such as answering machines and fax
machines. The CU consists of the following components:
control unit housing
carrier(s)
power supply module (one per carrier)
processor module
line/trunk and station modules
Control Unit Housing
The control unit is housed in a plastic cabinet for protection. The
size of the housing increases as expansion carriers are added to
the CU. Figure 1 shows how the control unit housing fits around
the CU.
Carriers
The basic and expansion carriers each have seven slots to hold
modules (see Figure 2). The basic carrier contains a power
supply module, the processor module (slot 00), and line/trunk
and station modules (slots 01–05).
Up to two expansion carriers can be added to the right side of
the basic carrier to increase the capacity of the system. Like the
basic carrier, the leftmost and widest slot of the expansion
carrier holds a power supply module; the remaining six slots hold
line/trunk and station modules.
Besides the slots, both basic and expansion carriers have a
backplane with an input/output (I/O) bus that provides the
interfaces with the modules.
Control Unit 1-5