ABSTRACT
Few developments have changed the face of automation so profoundly as the introduction of networks did. The fieldbus systems—networks devised for the lowest levels of the automation hierarchy—had an enormous influence on the flexibility and performance of modern automation systems in all application areas. This chapter presents an overview of the nature of fieldbus systems. It reviews the evolution from the historical roots up to the tedious standardization efforts. The chapter discusses the typical characteristics that distinguish fieldbuses from other types of networks, in detail. Current activities aiming at using Ethernet in automation are reviewed, and evolution prospects are presented. In the automation pyramid, fieldbuses actually populate two levels: the field level and the cell/process level. It appears that fieldbus systems have reached their climax and that future years will bring a mix of Ethernet-/Internet-based solutions and still-to-be-developed, new field-level networks.
