Understanding event propagation in IEC 61499 applications presents a significant challenge for control software developers. To address this issue, we adapted the well-known concept from software engineering called control flow graphs to create Event Flow Graphs. The purpose of developing Event Flow Graphs is to better understand and model event flow through IEC 61499 applications, and to see how the flow affects hardware and software components of the system. Our initial results show that Event Flow Graphs can accurately capture the properties of IEC 61499 models. This enables us to interpret common graph properties and invariants, and apply basic graph algorithms to query Event Flow Graphs efficiently. In addition, as an analysis tool, Event Flow Graphs represent a good alternative to visualize IEC 61499 applications, whose graphical and hierarchical nature can sometimes obscure event execution. The first findings indicate that Event Flow Graphs are valuable for analyzing and visualizing IEC 61499 software.

Control software in the Cyber-Physical Production System domain continuously evolves to cater to customer needs. Addressing customer needs involves developing new functional requirements or modifying existing functionalities, leading to the creation of product variants. Clone-and-own is a common reuse strategy in which the closest variant in project history is cloned and then modified to derive a new variant. Platform-oriented reuse is an alternative strategy that builds a configurable platform to derive variants. Adopting both reuse strategies for existing systems requires common and variant-specific artifacts to be extracted and maintained. This paper proposes two extraction methodologies that extract common and variant-specific artifacts from existing systems for systematic reuse. We evaluate the two extraction methodologies by applying them to multiple industrial and academic control software case study systems developed using IEC 61499. We conduct quantitative analysis of the extracted artifacts, considering factors such as the total effort required to derive variants, the number and size of artifacts that need maintenance, and their evolution using the two extraction methodologies. Our proposal suggests different variants of control software that lead to the creation of artifacts that are not only more optimal but also easier to maintain using a specific extraction methodology.

Bad smells negatively influence different aspects of software, such as maintainability and quality. From development to maintenance, smells contribute to error-proneness and control software is no exception. Code smells are starting to gain some popularity in the domain of industrial automation and programming languages for Programmable Logic Controllers. However, they are still not as well researched as in general Software Engineering and lack appropriate support. Shotgun Surgery is a type of bad smell which can occur when changing source code. If every time a functionality is updated, many of the places where it is used need to be updated as well - we can sniff out Shotgun Surgery. This poses different challenges: being aware of all the places where this particular functionality is used and correctly updating those places. We aim to bridge the gap between bad smells and control software partially. We want to do this by developing approaches for automatic detection, visualization, and refactoring of Shotgun Surgery in IEC 61499 applications in Eclipse 4diac IDE.

Bad smells are code patterns which have a negative influence on software, often impacting its quality and maintainability. Because of these negative effects, it is important to detect and avoid them. In the domain of software engineering, the topic of bad smells has been widely researched. On the other hand, in the area of industrial automation and PLC programming languages, bad smells have not received the same amount of attention. Shotgun Surgery is a code smell which we can find when a functionality is used in a certain number of places in code. It starts smelling when every change to the functionality requires many smaller changes to the places where it’s used. If we take a closer look at Shotgun Surgery in the domain of IEC 61499, we see that the general trend persists and that there is no adequate research done on it. In this paper, we want to identify Shotgun Surgery scenarios and showcase multiple existing and new approaches for its detection in IEC 61499.