When designing cyber-physical systems, especially in industrial automation, model-driven engineering plays an essential role in ensuring software maintainability and supporting evolution. Whereas textual programming environments provide mature tool support for refactoring and maintenance, equivalent capabilities in many industrial visual languages, such as IEC 61499 and Simulink, remain underdeveloped. This research addresses the challenges of maintaining and refactoring models in typed block-based modeling languages, such as IEC 61499 and Simulink, which are frequently used in industry. We propose a methodology that embeds repair mechanisms directly into refactoring processes, ensuring model consistency and minimizing manual intervention. By introducing a meta-model-based approach, we identify common maintenance operations and systematically define transformations that preserve the execution semantics while improving maintainability. Our approach is evaluated through a cross-language implementation, demonstrating its applicability across different modeling tools and industrial settings. We developed the concepts and assistance tools in close collaboration with our industry partner to enable software maintenance of large-scale automation software. The lessons learned are generalizable for various tool developers and contribute to error-resilient model evolution in visual modeling environments.

This paper proposes a novel library management system tailored for Cyber- Physical Production Systems (CPPSs) using the IEC 61499 standard. Focusing on software maintenance challenges in CPPSs, we introduce efficient updating and refac-toring operations for modularized type libraries. Our approach addresses the unique requirements of graphical development environments, enhancing the longevity and efficiency of software maintenance. The workflow of creating, maintaining, and up-dating library modules is outlined, along with conflict detection, error visualization, and potential refactoring/update operations. Additionally, we illustrate the architectural concept implemented as a prototype in an IDE. The implemented library management system demonstrates its practical application through a case study. This research contributes to the ongoing development of robust software maintenance practices in industrial automation systems.

Engineering Cyber-Physical Production Systems (CPPSs) heavily relies on Domain-Specific Languages (DSLs), which are tailored to a specific class of problems inherent to CPPSs. DSLs enable non-programming experts to solve problems in their domain, such as modeling production processes, implementing control software, or managing the variability of production systems. A DSL ecosystem encompasses the entire infrastructure (e.g., libraries and tools) built around its language and contributes to the successful and easy adoption thereof by domain experts. We present a maturity evaluation model for DSL ecosystems serving two aims: to developers, it reveals missing but essential aspects of the ecosystem, and users (e.g., industrial companies) can evaluate the maturity of a DSL ecosystem. We propose criteria to evaluate the maturity of DSL ecosystems and apply them to existing, publicly available DSLs which have been adopted in CPPSs. The results demonstrate that all components of the model are covered and they allow for deriving hypotheses about DSL ecosystems used in CPPSs.

In the domain of CPPS, long-term maintenance of software is necessary. Refactoring, a technique used to improve maintainability is a viable solution. However, there is a scarcity of research on refactoring in the context of CPPS. In this work, we propose a systematic approach for analyzing and deriving refactoring operations for IEC 61499. In particular, we propose a generic meta-model for block-based languages, which is accompanied by a corresponding generic refactoring catalog. Based on the generic meta-model, an existing refactoring catalog for IEC 61499 is extended by comparing and evaluating meta-models and their associated refactoring operations derived from literature of different modeling languages. We demonstrate that our approach provides a systematic way of transferring refactoring operations across block-based modeling languages and allows to extend existing refactoring collections for IEC 61499.

Errors of textual programming languages are usually detected by the compiler. These errors are then visualized by the IDE and made available to the developer. This paper is intended to show a novel approach to also propagate errors in visual programming languages to the developer. We analyzed the visual block-based language of IEC 61499 and implemented an error visualization mechanism in the Eclipse-based IDE 4diac. As IEC 61499 is a Domain-Specific Modeling Language (DSML) that includes a type system, we also implemented a mechanism for detecting inconsistencies. With this approach, it is possible to work on broken applications, giving developers the opportunity to fix them in a graphical editor. Furthermore, inconsistencies that lead to errors are now displayed rather than being hidden from the developer and hard to detect.

This work analyzes the problems that arise in IEC 61499 development due to the fact that there are no ways of structuring type libraries. As a result of this analysis we derived requirements for integrating modules into the IEC 61499 specification. The modules that are portable among several runtime providers and vendors can be imported into IEC 61499 systems. Every module contains a set of function blocks that can be used inside the application. The proposed IEC 61499 module has its own version and namespace. It is also capable of defining dependencies on each other. Reusability from types can be increased by dividing the type library into several parts with the help of the proposed modules.

Modern production plants are complex Cyber-Physical Production Systems with an ever-increasing share of software controlling and automating their operation. The customization of these systems to the needs of their customers and their frequent evolution over a typically long life-cycle result in a plethora of variants to be managed. However, reuse still is mainly done in an opportunistic way, relying on copy-paste-modify strategies. More systematic, strategic reuse would help to reduce costs and time to market, but requires approaches that can be applied to domain-specific languages for developing distributed control software. In this paper, we propose an approach to manage variability in IEC 61499-based systems using delta-oriented variability modeling. We discuss open challenges and outline a research agenda for variability management in IEC 61499.

Refactoring is a key technology for improving the quality of a software system. A higher quality will lead to a clearer structure, which facilitates sharing work across multiple teams. This is important especially in the domain of cyber-physical production systems, where different engineering disciplines meet at their cutting point. IEC 61499 tries to abstract the increasing complexity of such systems. This work gives an overview of existing refactoring techniques from software engineering and provides a first insight on how to apply refactoring to IEC 61499 systems.

Bad Smells are certain suboptimal structures or patterns in software. They can cause maintenance issues and hinder understandability. Therefore, it is essential to avoid Bad Smells in software. While the topic is well researched in other fields, it is still an open issue in industrial automation. In this work, we are taking a step towards closing that gap and propose a catalog of IEC 61499 Bad Smells.