Digital communication confronts us every day in modern process engineering: - it is used for configuring and setting the parameters for microprocessor instruments- serial bus systems, with minimum wiring requirements, are able to acquire a large amount of decentralized information and distribute it to the process equipment. Intelligent field and automation devices can communicate directly with one another via a digital bus.This book is intended as a step-by-step introduction to the subject of digital communications, for practical engineers and those new to this field. The emphasis is on clarifying generalized topics, as well as including some JUMO-specific applications.In this revised edition, the material on bus systems has been extensively updated. The method of operation of bus systems for which JUMO has field devices available is explained in a practical manner.Special thanks are due to all our colleagues, who helped us to prepare this book with their cooperation and professional input.