Microprocessors in the Processing Plant

Microprocessors have filled a gap in the possible approaches to control system design. Inherent features such as low cost, small size, improved reliability and programming flexibility have contributed to the popularity of the ``computer on a chip.´´ This tutorial paper surveys the microprocessor in industrial control environments. The rationale for a microprocessor design is examined in light of trends in hardware technology; advantages and limitations are discussed along with selection criteria and design guidelines. Various functional interfaces that link the process and the microprocessor are described with particular emphasis on input/output techniques. A new single chip 16-bit microprocessor is considered for several representative process control applications.