ABSTRACT
Historically speaking, the idea of achieving a data ®ow from the shop ®oor and the ¦eld level to the o§ce level together with proper network integration is not new. What is new is the current focus on Internet technologies as upper level of the interconnection. However, the integration idea itself was already part of the computer-integrated manufacturing (CIM) concept suggested in the 1970s [H73]. ¥e approach put forward then was to create a transparent, multilevel network to structure the information ®ow required for factory and process automation [DSP88]. To cope with the expected complexity, a strict subdivision of the information processing into a hierarchical model was devised that became to be known as the automation pyramid. ¥e model exists in various versions with diªerent naming conventions and numbers of levels, but it typically comprises four to six functional levels as depicted in Figure 13.1. Along with the de¦nitions of functionalities-which of course varied according to the application domain-networks were associated to the individual levels. Originally, diªerent networks were intended for these purposes. In recent years, however, the complexity of the pyramid, i.e., the number of levels was reduced chie®y because of the consolidation process that took place in the ¦eld of networking technologies. Today, the upper levels are dominated by IP-based networks (mostly on the basis of Ethernet) and, more generally, technologies from the o§ce domain, whereas the lowest level is still home to ¦eld-level networks in various forms.
