Fieldbus technology in industrial automation

Fieldbus technology in industrial automation is not only relatively complex because of the number of solutions possible, but also, and above,all, because of the variety of applications. Ironically, these in turn are responsible for the multitude of solutions available. If the analysis of the basic needs is relatively standard, as they will always involve connecting sensors, actuators, and field controllers with each other the options in architecture are numerous and can impose the need for certain services. The required performances themselves and the QoS expected fundamentally depend on the applications. This paper traces this technology from its beginnings, which go back to the first industrial networks in the 1970s. The principal stages of development are recounted, from the initial requirement specifications to the current state of international standardization. The diverse technical solutions are then analyzed and classified. In particular we study the temporal aspects, the medium access control protocols, and application relationships.