2001 Volume 14 Issue 12 Pages 574-581
In recent years, due to the fall of market price of plant control systems, improvement of the system engineering environment is required to increase productivity of the systems including control programs. In this situation, making reusable blocks of control programs, as represented by the function blocks of the international standard IEC61131-3, is attempted. However, the function block lacks the concept of abstraction of object-oriented programming. Therefore in the real situation, it is hard to construct reusable blocks. Furthermore, in the engineering of plant control systems, not only control programs but also process I/Os, equipment informations and specification documents have to be managed integratedly. In this paper, we present a new engineering model based on the object-oriented framework. The concepts of encapsulation and abstraction are introduced to the data-flow based graphical programming such as the IEC61131-3 function block diagram. A prototype engineering tool based on the model is also described.