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.

Cyber-Physical Production Systems (CPPSs), such as automated car manufacturing plants, execute a configurable sequence of production steps to manufacture products from a product portfolio. In CPPS engineering, domain experts start with manually determining feasible production step sequences and resources based on implicit knowledge. This process is hard to reproduce and highly inefficient. In this paper, we present the Extended Iterative Process Sequence Exploration (eIPSE) approach to derive variability models for products, processes, and resources from a domain-specific description. To automate the integrated exploration and configuration process for a CPPS, we provide a toolchain which automatically reduces the configuration space and allows to generate CPPS artifacts, such as control code for resources. We evaluate the approach with four real-world use cases, including the generation of control code artifacts, and an observational user study to collect feedback from engineers with different backgrounds. The results confirm the usefulness of the eIPSE approach and accompanying prototype to straightforwardly configure a desired CPPS.

Industrial-scale control software is designed as variability-intensive, i.e., highly configurable and adaptable software, to support diverse hardware capabilities and to fulfill diverse customer requirements. Various control software architectures have been proposed for developing highly configurable and adaptable control software. However, each architecture has its strengths and weaknesses in configurability and adaptability. Measuring the suitability of a given architecture to deal with variability can further guide control software engineers in implementing highly configurable and adaptable control software. In this paper, we propose measurement approaches for IEC 61499-based control software that indicate how well a particular architecture can manage variability. Control software engineers are first encouraged to describe all the functionalities in their system. They can also describe which elements must be added or removed when implementing a particular functionality. They then store these descriptions using a variability mechanism called delta models. Next, we can measure the size of delta models, the cohesion and coupling of the control software modules, and the degree of mapping complexity between features and delta models. We argue that by using our proposed measurements, we can indicate whether the control software’s architecture is suitable for variability-intensive software.

IEC 61499 is a standard for developing distributed industrial control software. It supports the configurability of the control software as the application model is platform-independent and separated from the system model that defines the hardware configuration specification. Thus, it can be used to develop control software for highly configurable Cyber-Physical Production Systems (CPPS). To address their customers’ requirements, companies that build CPPSs over time develop many variants of such production systems, typically through clone-and-own reuse, which increases engineering and maintenance efforts. Managing the control software variability in CPPSs in a systematic manner would facilitate software reuse and reduce the cost of developing and maintaining these systems. However, the IEC 61499 standard itself offers only limited capabilities for managing variability, e.g., by utilizing a library of modular components or by following certain design patterns. In this paper, we propose an approach to systematically manage IEC 61499-based control software using a (textual) delta modeling approach. Delta modeling is a prominent concept in the Software Product Line (SPL) domain for expressing and maintaining software variability. We show how our delta modeling approach can express control software variability and provide a semi-automatic control software generator. We evaluate the usability of our approach by applying it to multiple case studies as well as by performing a user study, in which control software engineers used our delta modeling approach. Our evaluation results indicate potential benefits of our delta modeling approach to implement and maintain control software through software generation.

Cyber-Physical Production Systems (CPPSs) consist of deeply intertwined physical and software components. In the last decade, the number of mechatronic components (sensors, actuators, etc.) in a system is increasing enormously to enable more flexible, intelligent production with more support for customization. Mechatronic variability, like different variants of sensors or actuators in the system, directly affects the control software. The standardization of physical interfaces of mechatronic components has provided well-defined plug-and-play interaction. Conversely, software components in the CPPS domain still face the issue of standardizing functionality. Software adaptability often leads engineers to develop control software for new mechatronic variants by just copying and modifying existing software. This leads to multiple and completely separate instances of the control software and a high development and maintenance effort. The core functionality of the control software should be standardized and reused as much as possible to reduce the development effort and improve overall reliability. This paper discusses an approach to standardize core functionality of IEC 61499-based control software. Our design approach encapsulates the process core functionality and defines standard interfaces for interacting with mechatronic variant software components. We evaluate our design approach by comparing it to the traditional clone-and-own approach for an academic case study system, a capping station. Additionally, we assess the impact of adding a new variant in the control software and analyze what changes are needed to keep the same core functionality. When introducing new mechatronic variants in combination with standardized core functionality, our design approach reduces the overall control software variance and maintenance effort.

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.

Cyber-Physical Production Systems (CPPSs) are complex, highly-configurable systems interacting with their environment by sensors and actuators. Software in CPPS typically exists in a plethora of variants, developed to fulfill customer and technology requirements, which have to be maintained over a long time. Support for variability management can foster systematic reuse and configurability, but this requires a significant investment of resources to explicitly document or model variability. Additionally, we need to define the reusable engineering artifacts and their variability corresponding to the documents or models. Furthermore, the documents or models need to be maintained and kept consistent with the artifacts evolving frequently. In this short paper, we propose to (semi-)automatically capture delta models describing differences be-tween CPPS control software variants and support generating these variants based on a product line platform. Specifically, we envision a change recording mechanism and model comparison approaches for control software developed using IEC 61499, a domain-specific modeling language used for developing distributed control in CPPSs. We argue that both approaches can significantly reduce the development and maintenance effort for delta models.

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.

automated Production Systems (aPS) represent a special type of mechatronic system characterized by a high complexity in hardware and software, lifetimes of up to several decades, and strong coupling of the involved disciplines, i.e., mechanics, electrics/electronics, and control software. Questionnaire studies have proven to be a valuable means of identifying obstacles in industrial software development that hinder the implementation of emerging technologies in the context of Industry 4.0 and, thus, the realization of Cyber-Physical Production Systems. However, the heterogeneity of different industrial sectors in terms of, e.g., the type of production processes or legal specifications, makes it difficult to compare the maturity of control software development across companies, even within the same industry. A software maturity benchmark for companies operating in similar industries is, however, a prerequisite for assessing a company’s strengths and weaknesses and thereby applying tailored solutions to improve the software and, thus, the competitiveness. This paper describes the results of a questionnaire study in two international companies operating in the same industrial sector. Specifically, location-, company-, and industry-specific maturity characteristics are analyzed and discussed, and it is concluded that the selected questionnaire is capable of identifying deviations and similarities in software maturity, even in an international environment, given that the companies are prefiltered based on the covered supply chain step. Hence, assuming a sufficiently large number of participants per industry, it enables a questionnaire-based industry comparison in future work, which was not possible until now.

We explore the possibility of including Delta-Oriented Programming (DOP) and Abstract User Interface (AUI) model during product generation in Software Product Line Engineering (SPLE). Previous work showed that DOP is applicable in a SPLE for Web applications albeit User Interface (UI) elements in derived product are still manually created without UI modeling. AUI model is proven to be successful for modeling UI elements for products in SPLE as it can model generic UI elements while still encouraging customization. Therefore, we pick an existing AUI modeling language called Interaction Flow Modeling Language (IFML) to create model of UI elements in a SPLE. We also suggest a new SPLE design that follows DOP and the proposed UI modeling language to generate adaptable UI given product configuration. The process of designing UI for each feature in the product line is based on reference implementation process used in previous work. We hope that the suggested process can solve the current DOP practices limitation in generating UI elements for products in SPLE.