Technical Application of Hybrid Modeling Methods to specify Function Block Systems

Abstract

In spite of large improvements of formal modeling methods, their technical application in industrial process control implementations is still rare. Two reasons can be pointed out. First, there is still a gap between the formal modeling languages and the control languages used in industrial process control systems respectively specified in normative standards. Second, the focus of the modeling aspects is mostly on the control algorithms itself. Looking at industrial applications, these pure control algorithms yield often just 10 % or less of the behaviour and the signal flows of a control unit. All other aspects like synchronisiation or occupying mechanisms are usually unconsidered. As a consequence of these arguments, first a new framework was developed for specifying modular function block applications in a comprehensive and formal way. Second, a generic template for batch-oriented process control blocks was designed, which takes all aspects of operational handlings into account. Both models – the framework and the template – are described using graphgrammars and hybrid modeling methods. The whole approach appears usefull for normative commitees and for large vendors of process control systems who have to develop function block applications or maintain and merge big function block libraries.