Graphical and Iconic Programming Languages for Process Control: An Object Oriented Approach

Abstract

Recent years have seen a proliferation of computers in the workplace, with a proportionate increase in the numbers of non-computer-literate people using them as part of their daily work. It remains necessary for programmers to provide such users with the programs to process, extract and display the information they require. However, the advent of micro computers incorporating high-resolution monitors that provide graphics facilities, seen previously only in large expensive workstations, has meant that another programming form has become viable. This form is called Visual Programming where the syntax of the language is graphical rather than textual.

The use of the object oriented paradigm to facilitate the implementation of interfaces both for graphical display and for visual languages is described.

Two approaches, graphical and iconic, are given as a means of providing high- level visual languages specifically for the area of process control. Careful design of such languages should ensure that non-programmers are able to design and implement an application themselves from a system without the need for a third party. This design must include the provision of a suitable human computer interface for the language and the issues involved in the development of such an interface must therefore be addressed.

The graphical and iconic languages, developed as part of the work addressed in this thesis, form part of an environment being developed for the design, implementation and maintenance of process control systems. This environment also requires graphical interfaces for other aspects of process control development. The object oriented approach taken is shown to promote the reuse of code and help maintain consistency over the different interfaces.