Abstract :
The IEC 1131-3 standard describes a set of related textual and graphical programming languages. They are related in the sense that it is possible to define the constructs of one language in terms of another. Furthermore, it is possible to mix and match the languages in a single application, using whatever is most appropriate for the part of the application being dealt with. Now that the standard has been internationally recognised, there is an upsurge of interest in it and many people are working on producing graphical programming tools. This paper has attempted to highlight just some of the many challenges facing the developer of an IEC 1131-3 tool, as well as perhaps to heighten the discernment and expectation of those seeking to purchase such a tool
