Control Software for Mechanical Systems: Object-Oriented Design in a Real-Time World

Chapter 14Programmable Logic Controllers (Plcs)

14.1 Introduction

Programmable logic controllers (PLCs) have established a firm place as control elements for mechanical systems. Because their dominant programming model is ladder logic, based on relay logic, they are usually viewed as an entirely different class of device than computer-based controllers programmed in algorithmic languages such as C. The result is separate, somewhat hostile communities of people, those who use PLCs and those who use computers.

Through the use of a task/state design and implementation model for mechanical system control software (mechatronic software) these two seemingly disparate means of implementing mechatronic system control can be reconciled. Because the ...