SPS Magazin has concentrated on the topic of engineering of control systems for a few months now, especially on programming. The reason for us investing that much in this issue is that software is a big part of automation engineering. In programming we were particularly interested in the subject of object-oriented programming (OOP). At this point, an interim conclusion may be granted: The topic of OOP has sneaked in and established itself in automation.
There are subjects that are not worth fighting over. Object-oriented programming of control seems to be one of them. I've been visiting several producers of controllers to interview them about engineering. So far I've done some interviews, and plenty will follow.
By now I have already see some interesting developments. I haven't met one provider who was not interested in OOP. But the points in which producers of controllers differ are strategies and the degree of realization. There are the ones that advertise their use of OOP; they merchandise the consequent use of this method of programming and see it as a competitive advantage. And there are others that do not use the technique continuously and who rarely or never use the concepts that go with it.
A third group of producers are using OOP only to make life a little easier for software engineers here and there, and to increase the re-usability of code. This group is not speaking out loud, however; they are using it silently.
If the wide market of controller programmers is to be addressed, it seems wise to introduce them to OOP step by step. Concepts such as class, inheritance, instantiation or polymorphy are obviously scaring PLC system programmers. The frequently invoked replacing of generations of programmers is taking years, and so it is not a surprise that OOP adoption is rather evolutionary.
The advantages of this technique are many:
• Dramatically improved re-usability of code.
• Advanced quality of programs.
• Working in a team is simplified.
• Administering codes is simplified.
• Essential simplification with changes.
No matter what a user’s personal opinion of object-oriented programming, in automation there is no way around OOP anymore. It is the duty of the producer to design and package the technique in a way, that reveals its use and that removes unnecessary barriers of concepts and theoretical ballast. Users are advised to get on board with object-oriented engineering sooner rather than later. Because OOP is the future—whether obvious or rather hidden doesn't matter.
Martin Buchwitz, [email protected], is editor of SPS Magazin in Germany.
