This paper introduces an innovative approach for the description and mapping of applications in the smart grid domain. By utilizing a skill-based engineering approach, not only flexibility and changeability will increase, but also the need for describing the same application multiple times for different grids decays. As a first use-case, Fault Location, Isolation, and Service Restauration (FLISR) as an example application and a real-world grid in Vietnam have been chosen. By showing how this novel approach could be applied to these two entities, its potential is demonstrated. The IEC 61850-based approach uses a two-step procedure for the mapping. After defining the application's requirements, a mapping algorithm can check if the application can be deployed to a specific grid. In the second step, the actual mapping is described to deploy the application to the devices in the field automatically. Having the requirement description, a recommender system can suggest possible adaptions to the grid in case the check fails.

Cyber-Physical Systems represent a fusion of spatially distributed digital and physical elements. Due to the increased complexity of such systems, understanding their holistic operational conditions becomes more and more challenging, especially for non-skilled operators. Event detection is a proven technique in this problem domain. However, manual event specification can be laborious and error-prone, motivating automated approaches. This paper proposes a knowledge-based event detection system that leverages abstract reasoning rules to derive time series event specifications from a system model. By automating the derivation of specifications, system integrators can focus on crafting event specifications for the system's intricate parts. Leveraging Semantic Web technology and Signal Temporal Logic, we evaluate the feasibility of the proposed approach in an electric vehicle charging scenario.

The ongoing transition in industrial automation towards a highly interconnected architecture underscores the importance of time-sensitive networking (TSN). This paper addresses the implementation of a time-predictable software-based TSN-enabled network stack for mixed criticality traffic in TSN end stations. The findings demonstrate the network stack’s worst-case execution time (WCET) analysability, effective management of mixed critical traffic, and real-time transmission of UDP frames. Additionally, the stack offers modularity, configurability, and TSN support for transferring messages across different priorities using either UDP or TCP. Evaluation on the time-predictable open-source T-CREST platform yields representative WCET estimates comparable to related research. The paper concludes by outlining further research.

The change of industrial automation towards a highly interconnected architecture is still ongoing. Time-sensitive networking (TSN) is an essential element for this transition. This paper focuses on TSN end stations, mainly answering how to implement a software-based worst-case execution time (WCET) analyzable buffer management. The two-level segregated fit (TLSF) algorithm was chosen, implemented, and evaluated based on an asymptotic complexity analysis of dynamic storage allocation algorithms. The implemented and improved TLSF algorithm showed similar timing behavior as calculated when executed on a time-predictable platform. The paper concludes by outlining further research.

Ongoing changes in industrial automation aim to-wards a flat and highly interconnected architecture that includes end-to-end real-time enabled machine-to-machine communications. Several technologies, such as OPC Unified Architecture (OPC UA) publish-subscribe and time-sensitive networking (TSN), facilitate that change. While OPC UA PubSub and TSN can already provide real-time capabilities, the parallel operation with standard OPC UA client-server remains an open challenge. This article presents preliminary results for solving concurrent information model access between OPC UA PubSub and client-server. The results include the overall RT-TSN-OPC UA concept, an analysis of common concurrent data access mechanisms for their suitability, and identifying critical code segments in the open62541 OPC UA stack. The paper concludes by outlining further research focusing on implementing and evaluating a wait-and obstruction-free mechanism into open62541.

Flexibility and reconfiguration of manufacturing systems have been subjects of research for almost half a century. In recent years, with the emergence of customized mass production as a goal of Industry 4.0 (I4.0), Reconfigurable Manufacturing Systems (RMSs) have experienced a renaissance. The objective of rapid reconfiguration of production facilities is a fundamental condition for the realization of customized mass production. Besides the configuration of machinery and their programs, this also affects the configuration of the safety system. In this paper, core characteristics of Reconfigurable Safety Systems (RSSs) are proposed, which extend the characteristics of RMSs. Furthermore, we explore use cases of discrete manufacturing and identify service groups and services that are needed for the technical implementation of rapid safety reconfiguration within RMSs in order to allow flexible, reliable, and safe operation of machinery.

Due to the increasing complexity of power grids, the development complexity of smart grid applications has continued to rise in recent years. Smart grid applications are currently being developed for specific power grids and not in a grid-independent way causing significant repetitive engineering effort. This paper gives an overview of the state of the art of application development in the smart grid domain, as well as approaches that try to cope with the mentioned problem. In particular, solutions are examined where the grid-independent application is modeled using a functional description. These approaches are then reviewed for limitations and weaknesses in order to make suggestions on how an integrated framework for the development of such applications could look like. Finally, an overview of research questions to reach this goal is presented.

An important field of application for the Internet of Things (IoT) is the area of monitoring and control, which imposes requirements on dependability. As devices in the IoT become increasingly capable, they can make use of concepts and technologies provided by the area of knowledge engineering to cope with these requirements. Existing work in this area mainly covers dependability threats and means, but dependability attributes are less well investigated.This paper presents a dependability rating ontology that enables the quantification of dependability attributes and, thus, makes them comparable. This is achieved by combining a dependability tree ontology with an ontology covering metrics and scales. IoT devices can use the dependability rating ontology, e.g., to improve their control algorithms, which is demonstrated on the switching optimization problem, a Smart Grid use-case.

Industrial automation is changing towards a flat and highly interconnected architecture, with requirements for end-to-end real-time enabled machine-to-machine communications. Technologies such as time-sensitive networking (TSN) and OPC Unified Architecture (OPC UA) publish-subscribe provide the necessary features. While TSN is well explored, OPC UA's execution time behavior remains unknown. This article presents findings made while extending the open62541 OPC UA Pub Sub stack with the 802.1q VLAN tag to enable IEEE 802.1Qbv time-aware scheduling. The results include end-to-end timing measures and worst-case execution time analyses considering various payloads. Time-predictable T-CREST platforms host the publisher and subscriber, and a TSN network handles message transmission. The paper concludes by outlining further research focusing on dynamic memory access, buffer management, and the inclusion of non-priority access to the Ethernet port.

Discrete manufacturing and process industries move towards flexible production to cope with individualization. Safety systems often counteract these developments. In this paper, a generalized methodology to draft an overall safety concept using different technologies is presented. Motivated by use-cases from both domains, requirements for future safety systems are described and summarized in a structured way. These requirements are then generalized and classified in building blocks to fulfill the needs of flexible functional safety. A methodology to structure safety systems and their general parts is presented. The used building blocks refer to aspects as interfaces, communication, and certification. Within the building blocks different technologies can be applied, to fulfill the part of the safety system accordingly.

In Cyber-physical Production System (CPPS) engineering, data analysts and domain experts collaborate to identify likely causes for quality issues. Industry 4.0 production assets can provide a wealth of data for analysis, making it difficult to identify the most relevant data. Because data analysts typically do not posses detailed knowledge of the production process, a key challenge is to discover potential causes that impact product quality with various experts, as knowledge about production processes is typically distributed across various domains. To address this, we highlight the need for cross-domain modelling and outline an approach for effective and efficient quality analysis. Specifically, we introduce the Quality Dependency Graph (QDG) to represent cross-domain knowledge dependencies for efficiently prioritizing data sources. We evaluate the QDG in a feasibility study based on a real-world use case in the automotive industry.

Worst-case execution time (WCET) analysis is a prevalent way to ensure the timely execution of programs in time-critical systems. With the advent of new technologies such as fog computing and time-sensitive networking (TSN), the interest in timing analysis has increased in industrial communication. This paper highlights experiences made while adjusting the publisher of the open62541 OPC UA stack to enable WCET analysis, following a simple process combined with the open-source platform T-CREST. The main challenges are the required knowledge about the code and the specific communication software characteristics like variable message sizes. Other findings indicate the need for other types of annotation for indirect recursion or callback functions. The paper provides the foundation for further research on adjusting the implementation of existing industrial communication protocols for WCET analysis.

Industrial automation is changing towards higher integration and seamless communication. A stepping stone is end-to-end real-time machine-to-machine communication, now becoming feasible with technologies such as time-sensitive networking (TSN) and OPC Unified Architecture (OPC UA) publish-subscribe. While TSN takes care of communication, the OPC UA stack's execution time behavior remains unknown. This paper highlights experiences made while adjusting the OPC UA subscriber of the open62541 stack for worst-case execution time (WCET) analysis. Two directly connected time-predictable T-CREST platforms hosting the publisher and subscriber delivered end-to-end timing measures validating the WCET estimates. The paper concludes by outlining further research with several time-predictable publishers and subscribers.

Smart manufacturing is realizing the idea and potential of Industry 4.0 in reality. An essential part of smart manufacturing are production facilities that dynamically adapt to changing production needs. This brings completely new challenges to functional safety systems, which are mandatory for the protection of man, machine, and environment. Currently, functional safety systems are designed and certified in a static way. The safety design and the configuration are derived from the risk assessment which is performed during the design of a machine. Once the system is put into operation, the safety configuration is not changed anymore. This approach constitutes an impediment to flexibility which smart manufacturing production facilities require nowadays.This paper proposes the design of a self-organizing safety system with the objective to assist an engineer who operates a smart manufacturing facility by discovering all safety-related devices and generating automatically a suitable safety configuration. This configuration will be deployed to the system automatically after adaptation and validation by the safety engineer. The proposed self-organizing safety system, simplifies the safety configuration in a dynamically changing environment. Consequently, it would reduce engineering efforts and decrease machine downtime which improves profitability.

Transmitting time-critical data like safety applications over the traditionally not real-time capable Ethernet standard (IEEE 802.1) requires modifications. Compared to devices, individually connected by signal wires, "network-attached" safety components offer more flexibility in their usage by making their data available to all factory entities instead of just one counter partner. openSAFETY - open-source standard for safety-related applications - enables functional safety, that can be integrated in any network with deterministic behavior. Time-Sensitive Networking (TSN) - a set of IEEE standards that can be applied to IEEE 802 networks - offers the possibility to run Ethernet traffic with real-time requirements without the traditional problems of Ethernet like frame dropping or timing issues. This paper proofs the concept of these two technologies being a suitable combination to transmit time-critical safety data and non-priority traffic within a single Ethernet-based network. Several tests were made to show how TSN can host an openSAFETY-application in different scenarios including background traffic. The results show adequate performance of this system in terms of reliability under worst possible conditions like external broadcast traffic blocking the entire bandwidth.

Cyber Physical Production Systems have a need of sharing and interlinking information and knowledge over different domains. In the area of industrial automation, OPC Unified Architecture (OPC UA) is a widely used and established standard for communication and information modeling. We propose an ontology-based OPC UA data access method utilizing custom property functions, which enables interlinking between OPC UA information and other factory data. To avoid duplicated data and to reduce the communication overhead in the proposed method, the OPC UA run-time data are loaded on-demand and are not persistently stored in the triplestore. To enable fast and easy ontology-based access and interlinking of the OPC UA information, the needed ontology is automatically generated from the OPC UA information model. A proof of concept demonstrates the application of our approach for a laboratory use-case of a Packed-Bed Regenerator.

Due to its modeling capabilities, platform independence, and extendability, Open Platform Communications Unified Architecture (OPC UA) is considered to be the main candidate for a so-called “enabling technology for industry 4.0”. However, the engineering effort for OPC UA applications, in particular the server, is very high as the process of information modeling and linking the resulting model to real-world data is complex and time-consuming. This significantly limits the spread of OPC UA in manufacturing and other domains.This paper presents an approach towards extending OPC UA in a way such that information necessary for the OPC UA server application to access the underlying system can be specified in the information model. This is achieved by defining communication interfaces for all nodes of the information model that represent readable or writable data. The handling of the interfaces needs to be implemented in code only once and from then on they can be modeled, rather than implemented for each node individually. Thus, the implementation effort of OPC UA servers is reduced. Different modeling approaches for communication interfaces are presented and compared.

Information and communication technology plays a crucial role in increasing reliability and efficiency of our critical infrastructure. This paper presents a distributed multi-agent system for switching optimization in low-voltage power grids. As opposed to centralized approaches, the overall optimization procedure is not implemented in a single node but emerges from the behavior and interaction of the participating agents. Thereby, the communication strictly follows a predefined interaction protocol. Losses are reduced by balancing loads among all available transformers. Based on a small distribution network, an exemplary optimization run is discussed in detail. Furthermore, FNCS, a state-of-the-art co-simulation framework, is used to evaluate the actual potential for energy saving.

The number of devices connected to the Internet of Things (IoT) has steadily been increasing over the last years and so has the variety of applications. There is no sign for this trend to weaken. A broad subset of them imposes requirements on attributes, such as availability, reliability, safety and many more. These attributes are commonly subsumed under the term dependability. In this paper we first give a brief introduction to dependability. Three application scenarios typical for the IoT are presented and their demands for each dependability attribute are discussed. Furthermore, an overview of the current state of the art is presented. Last, a summary of required technologies and future research topics to enable dependability in the IoT is given.

Currently, an increasing number of initiatives are observed aiming at enriching automation environment with modern Information and Communication Technologies (ICT). The desired solutions should lead to increasing and facilitating interoperability of production systems and their components. To realize this vision, a key component is an open and standardized communication platform. Meanwhile, OPC Unified Architecture (OPC UA) is accepted as communication solution, especially because of its capabilities to create extensible information models. As part of the ongoing research project OPC4Factory, semantically rich OPC UA interfaces based on specific information models for a robotized manufacturing cell are developed. In addition to the static hierarchical structure, the information model should also describe the dynamic behavior of the modeled system. State machines provide proven means to model the dynamic behavior of manufacturing machines. However, whether a transition of a state machine can be executed often depends on certain conditions. In UML, these conditions are reflected by guards. Unfortunately, a similar functionality is neither provided by the current OPC UA specification nor by companion standards. For this reason, an amendment to the OPC UA information model is introduced, enabling guards in OPC UA. Thereby, new object and reference types allow to model operations in an OPC UA server's address space. Exposing this information has several advantages over hiding it in the server's source code regarding the required implementation effort as well as the client's possibilities to react to rejected transition requests.