This book gives an introduction to the programming language Structured Text (ST) which is used in Programmable Logic Controllers (PLC). The book can be used for all types of PLC brands including Siemens Structured Control Language (SCL) and Programmable Automation Controllers (PAC). This 3rd edition has been updated and expanded with many of the suggestions and questions that readers and students have come up with, including the desire for many more illustrations and program examples. CONTENTS: - Background, benefits and challenges of ST programming - Syntax, data types, best practice and basic ST programming - IF-THEN-ELSE, CASE, FOR, CTU, TON, STRUCT, ENUM, ARRAY, STRING - Guide for best practice naming,