This practical book gives a comprehensive introduction to the concepts and languages of the new standard IEC 61131 used to program industrial control systems. A summary of the special requirements in programming industrial automation systems and the corresponding features in the IEC 61131-3 standard makes it suitable for students as well as PLC experts. The material is presented in an easy-to-understand form using numerous examples, illustrations and summary tables. There is also a purchaser's guide and two CD-ROMs containing two reduced but functional versions of programming systems. These increase the value of the book for PLC programmers and for those in charge of purchasing software in industrial companies.