OPC - Making the Fieldbus Interface Transparent

The performance of fieldbus systems has been studied more or less thoroughly. With the advent of high speed fieldbus systems as PROFIBUS-DP the bottleneck of systems moves from the communication to the application, especially to the interface between both. Two requirements are placed on such interface in general. First it should be based on an open, accepted standard where secondly it should support real-time operation. As the PC becomes more and more important even in the realm of industrial automation the quality of interfaces based on Microsoft Windows technologies gains importance too. The first solution provided with Windows 3.1 was the Dynamic Data Exchange (DDE). Although an open an finally widely accepted standard its communication performance was not satisfactory. The development of the OPC (OLE for Process Control) architecture aimes at solving the question of performance while providing an open interface standard between applications. Although the openness of this solutions is not debatable, the performance issue has to be investigated. This paper contributes to this by exploring the performance of an implementation of the OPC interface standard.