Page 352 - Programmable Logic Controllers, Fifth Edition - Mobile version

15

ControlLogix Controllers

system, CompactLogix system, FlexLogix system,
SoftLogix 5800 controller, and DriveLogix sys-
tem. Software is the essential difference between
PACs and PLCs. Basically, the ladder logic con-
figuration does not change but the addressing
of the instructions changes. Application of the
software that pertains to the Logix control plat-
form of controllers will be covered in the various
Programmable logic controllers continue to sections of this chapter. Knowledge of basic lad-
evolve as new technologies are added to their der logic instructions and functions (bit, timer,
capabilities. The PLC started out as a replacement counter, etc.) covered in previous chapters of
for banks of relays used to turn outputs on and the text is assumed and is thus not repeated in
off as well as for timing and counting functions. this chapter.
Gradually, various math and logic manipulation
functions were added. In order to serve today’s
expanding industrial control system needs, leading
automation companies have created a new class
of industrial controllers called programmable
automation controllers or PACs (Figure 15-1).
They look like PLCs in their physical appearance
but incorporate advanced control of communica-
tion, data logging, and signal processing, motion,
process control, and machine vision in a single
programming environment.
The Allen-Bradley programmable automa- Figure 15-1 Programmable automation controllers (PACs).
tion controller family includes the ControlLogix Source: Image Courtesy of Rockwell Automation, Inc.

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