Abstract

One of the key issues in automation is the exchange of information, and substantial efforts were devoted in the past to introduce communication systems at all levels of the automation hierarchy. The original goal was geared toward vertical data transfer between the levels. Nevertheless, as appropriate networking concepts were still in their infancy or entirely missing at that time, academic and industrial activities focused on the development of dedicated automation networks and thus primarily on horizontal integration aspects. Many different networks emerged: fieldbus systems of all kinds, Ethernet-based networks, and wireless concepts tailored to automation purposes [1]. Even though early publications did foresee the use of gateways between the individual networks for protocol conversion [2], true integration was not a primary goal for system developers, and so the lower automation levels remained largely separated from the upper, office-oriented levels in terms of data exchange and application integration [3].