Strategy for the amendment of plant information models by means of OPC UA

Companies with established and reliable control systems are often confronted with the question of how to benefit from upcoming innovations in science and practice without removing or extensively changing their systems. One of the currently often discussed innovations is the new standard OPC Unified Architecture (OPC UA). OPC UA provides an improved data transport and a semantically rich information model with the aim to improve operators supervisory and control tasks. OPC UA is a promising candidate to provide the next generation platform for control system development that better meets today's technological and business requirements. However, during our research activities over the last three years in two projects with industry partners, we encountered difficulties in introducing OPC UA concepts into existing control systems as many currently proposed integration solutions either replace existing systems or provide technology-driven integration solutions which are unable to reveal the innovational strength to operators and engineers. Companies wishing to benefit from upcoming OPC UA concepts and adjust their control systems towards the state of the art also wish to protect their investments in existing tools, data sources and employees' training. In this paper we approach OPC UA from a user-centered design view. We first derive requirements on how to improve the operators' and engineers' work situation. Subsequently we show which OPC UA information model properties can cope with these requirements in a standardized way. Finally we present our observations on the challenges faced by companies when introducing new technologies into existing control systems and we propose an evolutionary strategy on how to combine existing tools and models with new concepts.