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PROGRAMMABLE LOGIC CONTROLLERS
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.orgCitation: (doi:10.13031/2013.17770) in Programmable Logic Controllers. Chapter 10 in Fundamentals of Electricity for Agriculture, 3rd edition, 277-300. St. Joseph, Michigan: ASAE. . Copyright 2004 American Society of Agricultural and Biological Engineers, St. Joseph, Mich.
Authors: Gustafson, Robert J., and Mark T. Morgan
Keywords: PLC Construction, PLC Operation, I/O Module Details and Connections, Operating Modes, PLC Programming, PLC Addressing, PLC Instructions, IEC 61131-3 PLC Programming Standard
This chapter will cover the basics of programmable logic controllers (PLCs). PLCs
can perform all of the functions of relay-based control systems and much more. They
have replaced hard-wired relay-based control systems in most industries because of
their compact size, ruggedness, and most importantly, their ability to be easily reprogrammed.
Changes in a control system or process function can be made with minimal