Graphical and iconic programming languages for distributed process control: an object oriented approach

Distributed process control has gained in impetus over recent years as an alternative to central control systems. The object-oriented paradigm lends itself well to the description of such distributed systems. The Oscar model of active objects embodies this paradigm, and a support environment for the design and implementation of process control systems built on this model is outlined. A graphical system description language based on an extended GRAFCET notation is described. This language is used to specify the interobject messaging and action required for a particular control task. The parsing of the diagram provides the code for controlling a system. A higher-level iconic approach to the description of control strategies is also described. By restricting themselves to the domain of process control, the authors have been able to make substantial progress in the provision of an integrated support environment. The environment incorporates the notions of visual programming techniques and combines iconic and object-oriented paradigms to produce a consistent interface metaphor.<>