Written for programmable logic controller programmers, this book describes how to create a functional machine control program for industrial equipment that is sequential in nature.The programming methodology starts by breaking the machine into its basic elements. These small and manageable elements allow the programmer to focus on large concerns before dealing with specifics. The methodology then shows how to program each element and how to assemble the elements together into a complete machine control program. The book is intended to provide programmers with the confidence they need to reach decisions, and move forward with the certainty that the program is performing as intended without odd combinations of logic causing unintentional actions. The sequential nature of events will also help operators and maintenance personnel troubleshoot and maintain the equipment after it is put into operation. Ladder logic illustrations demonstrate each part of the text. Although the ladder logic examples use the instruction set for the Allen Bradley SLC 500 programmable logic controller, the concepts and techniques can be used with any brand of programmable logic controller.