Combination of UML Modeling and the IEC 61499 Function Block Concept for the Development of Distributed Automation Systems Seno Panjaitan and Georg Frey University of Kaiserslautern, FB EIT, JPA² Erwin-Schroedinger-Str. 12 D-67653 Kaiserslautern, Germany e-mail: (panjaitan,frey)@eit.uni-kl.de Abstract This paper proposes Unified Modeling Language (UML) as modeling tool for distributed control systems (DCSs) according to the IEC 61499 standard. The rea- son behind using this model is a demand to describe the system considering the whole development process. The Object-Oriented (OO) concept in UML along with its supporting tools is a good candidate for this pur- pose. However, IEC 61499 is built on the use of inter- connected Function Blocks (FBs) as a modeling para- digm. A mapping concept from UML into FB-based systems and its implementation are presented. As a re- sult, the UML model using class diagrams, packages, and state diagrams can be transformed automatically to models according to IEC 61499. The proposed process leads to a combination of previously disjoint design levels in the system development. 1. Introduction Today, system development tends to be more com- plex due to the effect of dynamically changing market demands. Consequently, the design process should not just consider a particular step in the system develop- ment such as software modeling, but also include the whole scheme to deal with more complete description. For that reason, the Unified Modeling Language (UML) seems to be a suitable tool since it provides various diagrams to cope with different steps in the de- velopment process and allows building models on dif- ferent levels of abstraction. In the automation domain, the IEC 61499 [1] has proposed some reference models to be the framework in Industrial Process Measurement and Control Systems (IPMCSs) regarding distributed control systems (DCSs). It retains the use of previous programming methods in basic components built on the – by now accepted – standard IEC 61131 for the programming of Programmable Logic Controllers (PLCs). One goal surely was to allow an easy migra- tion from the previous concept, in order to make the new one more acceptable by practitioners in the field of automation. The main concept of IEC 61499 is to build a system by the interconnection of Function Blocks (FBs). These FBs share information by event- based communication mechanisms and encapsulate their private data and algorithms. For the description of the algorithms themselves the languages of IEC 61131 are proposed. Therefore, IEC 61499 provides good concepts for the (fine-grained) design and the imple- mentation of a DCS. However it lacks in support for the other steps in the development process. In the beginning steps of system development such as requirement analysis and first (high-level) design decisions as well as in the analysis of the system structure and functionality other modeling tools are re- quired. In the software engineering domain, UML is the predominant choice for these tasks today. UML can be used to cover the tasks that are not covered by IEC 61499. Furthermore, it can bridge the gap between software design and automation engineering, if a trans- formation of the results from UML to IEC 61499 is provided. As a result, two alternatives are open: The first alternative is completely modeling the system using UML tools and then automatically transforming it to an FB environment by producing code according to some data-interchange standard of the FB runtime system. The second alternative will use UML only to describe aspects not well covered in IEC 61499 and generate a partial model to be completed using FB tools like FBDK [2] or CORFU [3] (e.g. structure generated in UML with algorithms designed in the FB environment). In both cases, the aim is to give better comprehensibility not just in programming level, but also in the different steps of system development. The rest of this paper is organized as follows. Sec- tion 2 will present some reasons why UML should be used in combination with IEC 61499 and how it is al- ready used in other approaches. Section 3 details the concept and the software implementation for the trans- formation followed by Section 4 which illustrates the result using an example. Finally, Section 5 will con- clude the paper and give an outlook on further work. 766 1-4244-0681-1/06/$20.00 '2006 IEEE