Programmable Logic Controllers: The Hardware

Author

Kelvin T. Erickson, Missouri University of Science and TechnologyFollow

Abstract

In many respects, the architecture of the programmable logic controller (PLC) resembles a general-purpose computer with specialized input/output (I/O) modules. However, some important characteristics distinguish a PLC from a general-purpose computer. First, and most importantly, a PLC is much more reliable, designed for a mean time between failure (MTBF) measured in years. Second, a PLC can be placed in an industrial environment with its substantial amount of electrical noise, vibration, extreme temperatures, and humidity. Third, plant technicians with less than a college education can easily maintain PLCs.

This chapter describes the main distinguishing characteristics of the PLC, its basic hardware and software architecture, and the method in which the program and I/O modules are scanned.

Recommended Citation

K. T. Erickson, "Programmable Logic Controllers: The Hardware," A Guide to the Automation Body of Knowledge, 3rd Ed., pp. 225 - 232, International Society of Automation (ISA), Sep 2018.

Department(s)

Electrical and Computer Engineering

Comments

Chapter 13

International Standard Book Number (ISBN)

978-1-941546-91-8; 978-1-5231-1915-8

Document Type

Book - Chapter

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2018 International Society of Automation (ISA), All rights reserved.

Publication Date

24 Sep 2018