Steven Braun

Evaluation of a UML-Based Versus an IEC 61131-3-Based Software Engineering Approach for Teaching PLC Programming

A field experiment investigated the evaluation, teaching, and application of two different approaches to automatic control in programmable logic controllers, in particular comparing the Unified Modeling Language (UML) to the classic procedural paradigm (IEC 61131-3). A total of 85 apprentices from a vocational school for production engineering with a specialization in mechatronics took part in the training and the experiment. This paper details the results of the training using both approaches, and the correlations found between the modeling and/or programming performance and cognitive abilities, interest, workload, expertise, and school grades. In general, the results show that students can be trained to carry out authentic programming tasks within one and a half days, even for beginners in programming. The data distinguish the two approaches. Function Block Diagram programming (IEC 61131-3) can be best predicted by the grade in mathematics, programming experience, and cognitive demand. For performance in UML class diagram and state chart (UML/CD+SC) modeling, the grade in mathematics plays an even more prominent role; this explains the greater variance in modeling performance in the UML group than in the 61131/Function Block Diagram group. With respect to other findings, the paper concludes that special problem-solving skills and skills for abstract thinking should be taught when teaching UML-based modeling approaches.

Implementation and evaluation of UML as modeling notation in object oriented software engineering for machine and plant automation

Abstract Our goal is to increase efficiency and quality in automation engineering in machine and plant manufacturing industry by supporting modularity and reuse. This article proofs that object-oriented model-based design can beneficially be applied in industry and that the code automatically derived from the UML model can be implemented on industrial PLCs without additional effort. We had to solve the formal mapping from UML models to IEC 61131-3 program code in order to use an object-oriented approach with Unified Modeling Language (UML) as modeling notation integrated into a classical Programmable Logic Controller (PLC) programming environment (IEC 61131-3).

Requirements on Evolution Management of Product Lines in Automation Engineering

Abstract The initial investment costs for a production plant are enormous – in many cases up to 100 Mio. €, and the entire life-cycle is up to 30 years. In order to preserve existing investments and to retain the competitiveness of the production plant it continuously has to be developed and improved further. In consequence, basic modules (software, electric, and/or mechanic) as well as application modules (product line based combination of basic modules) have to be upgraded during the entire life cycle of the automation system in cooperation of plant owner and module supplier. Therefore two essential topics have to be considered: a) an integrated variant- and version management of basic modules, application modules based on product lines, and modules, which are part of production plants in the field and b) an interdisciplinary compatibility supervision technique to validate the compatibility of new module versions with respect to the various application contexts and the complex dependencies between software (software design), platform (electrical design) and/or context (mechanical design). Both challenges can only be resolved with an appropriate tool support for variant and version management of modular models and for model validation to supervise the interdisciplinary compatibility. To provide this tool support a syntactic and semantic formal model is necessary. In this paper the requirements on a holistic mathematical modeling of evolution in automation engineering are proposed.

Usability evaluation on teaching and applying model-driven object oriented approaches for PLC software

In machine and plant automation, model-driven object oriented (oo) programming of Programmable Logic Controller (PLC) software is becoming an alternative to the state-of-the-art programming. The authors present the results of previously conducted experiments on the usability of the classic procedural paradigm (IEC 61131-3) compared to model-driven approaches for PLC programming, in particular Unified Modeling Language (UML) and domain specific modeling languages. Subsequently, the newest study on this issue is presented, including the experimental design and the experiments parameters, comparing state-of-the-art FDB (IEC 61131-3) programming approach to a model-driven UML supported approach. Finally, we show the studys results and discuss our findings and their meaning for future experiments, concerning the complexity of the tasks required to develop a PLC-program, the influence of previous knowledge, and the realization of constant boundary conditions for experimental studies.

Fundamental Aspects Concerning the Usability Evaluation of Model-Driven Object Oriented Programming Approaches in Machine and Plant Automation

Within the world of automation the trend of model-driven object oriented (oo) engineering has brought up fundamental questions about the applicability of these programming paradigms for Programmable Logic Controller (PLC) software. The authors present the results of previously conducted experiments on the usability of the classic procedural paradigm (IEC 61131-3) in machine and plant automation compared to model based approaches for PLC programming, in particular Unified Modeling Language (UML) and domain specific modeling languages. Extrapolating these experiments, we propose a way of enhancing usability evaluations by two means: First we present an improved modeling tool. Second, in order to determine the complexity of the tasks required to develop a PLC-program and to create constant boundary conditions for experimental studies, we propose using Hierarchical Task Analysis (HTA) on both model-driven oo and the state of the art programming approach, concerning typical scenarios. Finally the results of our work are discussed.

Usability evaluation of modeling notations for software engineering in machine and plant automation

During the last eight years we investigated the benefit of modeling notations, e.g. UML and domain specific UML profiles as well as specialized modeling languages (Idiomatic Control Language - ICL) in software engineering (IEC 61131-3) in machine and plant automation with three different experiments and approximately more than 120 participants. The results of the conducted experiments revealed the benefits and the shortcomings of UML in the field of supporting control programming. Furthermore we can show the impact of different modeling notations on software quality (IEC 61131-3) and time consumption for the software development process as well as some results on how to evaluate model driven engineering under usability aspects.

Modeling order effects on errors in object oriented modeling for machine and plant automation from an educational point of view

Our goal is to improve the handling of new possibilities given through object-oriented extension of the IEC 61131–3 programming techniques. We already know that modeling of structure is a challenge for automation engineers and often neglected. In an interdisciplinary research team we examined whether the modeling order with the Unified Modeling Language (UML) class diagram for the structural aspect and the UML state chart diagram for the behavioral aspects cause significant differences in model quality. Additionally, often occurring errors were analyzed to find hindering factors in modeling and to learn what was misunderstood. Therefore we combine usability aspects, notational and procedural aspects in PLC programming with learning and educational aspects to find how education and application of modeling notations could be improved.

Usability challenges in the design workflow of reusable PLC software for machine and plant automation

Software development for PLC based systems is changing. In addition to the traditional, procedural programming languages for Programmable Logic Controllers (PLCs) from the IEC 61131-3, increasingly object-oriented elements are used, as defined in the object-oriented extension of IEC 61131-3. This paper discusses observed effects of the change on the usability of design methods for software developers. Subsequently, a model-driven, tool supported approach for automation systems is presented. Finally, an outlook on the next steps for the realization of the underlying concept is given.

Notwendigkeit von Metriken für neue Programmiermethoden automatisierungstechnischer Anlagen

Die Softwareentwicklung fur Echtzeitsysteme befindet sich im Umbruch. Neben den klassischen, prozeduralen SPS-Programmiersprachen der IEC 61131-3 kommen zunehmend objektorientierte Elemente zum Einsatz, wie sie auch in der objektorientierten Erweiterung der IEC 61131-3 definiert werden. Dieser Artikel erlautert die zu erwartenden Effekte der Umstellung auf die Komplexitat und Modularitat von automatisierungstechnischen Echtzeitsystemen und auf die Usability der Entwicklungsmethoden von Seiten der Softwareentwickler. Abschliesend wird ein Forschungsansatz fur die vollstandige Komplexitatsmessung von automatisierungstechnischen Echtzeitsystemen fur die Erstellung einer domanenubergreifenden Metrikensammlung vorgestellt.