Andreas Fernbach

Interoperability at the management level of building automation systems: A case study for BACnet and OPC UA

In modern building automation systems a plethora of different networking technologies exists. Therefore, interoperability between devices using various technologies is a key requirement. The use of Web Services as a platform-and technological-independent method of communication is a promising approach to address this challenge. Since IP extensions to available technologies are more and more established in building automation systems the network infrastructure and necessary protocols for Web Services communication are already present. However, providing appropriate concepts to model information that can be accessed in a generic way are still missing. OPC Unified Architecture (OPC UA) is a powerful and promising standard that aims at solving this challenge. This work discusses an approach to map the interworking model of BACnet to OPC UA. Using the resulting information model BACnet applications can be represented in OPC UA and, thus, be accessed by OPC UA clients in a standard and well-defined way.

Certificate management in OPC UA applications: An evaluation of different trust models

OPC Unified Architecture (OPC UA) provides a powerful and inherent security model. These mechanisms rely on software certificates. In an automation system where OPC UA is applied, a strategy must be defined how to manage these certificates, i.e. an organised way of distribution, validation and revocation needs to be found. In general, there exist different concepts of how to achieve this goal. Moreover, there are various, in some cases platform dependent frameworks available which assist the developer in implementing a suitable concept. The aim of this paper is to give an overview of these concepts and frameworks and discuss their positive and negative aspects depending on the structure of different environments in which OPC UA applications shall be embedded.

Linked data for building management

In the life cycle of buildings, plenty of different disciplines and companies are involved. Therefore, a unified information base for the whole building and its components and technical equipment is highly beneficial. One approach aiming at this goal is Building Information Modelling (BIM). There exist standards mostly focusing on architectural and building physical properties, like the Green Building XML schema (gbXML). A further improvement would be to include a description of the technical equipment and building automation components as well, and to make the resulting model accessible in a unified way. This paper aims at a holistic knowledge base for buildings providing views on static building and automation systems configuration as well as runtime information, i.e., access to live values of datapoint originating in the building automation systems. This includes sensor values, setpoints, calculated or aggregated values as well as time series of historical values.

An OPC UA information model for cross-domain vertical integration in automation systems

Bridging the two domains of building and industrial automation systems at their management levels is a topic hardly regarded so far. Nevertheless, cross-domain integration promises significant benefits in terms of resource consumption and costs optimisation where systems of both worlds encounter each other. To this aim, this work presents an OPC UA information modelling framework providing a holistic information base for both domains. This facilitates the implementation of cross-domain management applications in the context of smart grids with the potential goals to coordinate the reuse of waste energy, to avoid peak loads and to predict energy demand.

An OPC UA cross-domain information model for energy management in automation systems

Interoperability between different technologies in the industrial and building domains of automation has already become a significant research topic. Extending this thought towards cross-domain interoperability, synergy effects arise from the resulting unified view to process data of both domains. This facilitates savings of energy, working time and materials. In this work a cross-domain information model aiming at this goal is proposed.

Guarded state machines in OPC UA

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 servers address space. Exposing this information has several advantages over hiding it in the servers source code regarding the required implementation effort as well as the clients possibilities to react to rejected transition requests.

Integration of smart meters into management systems in automation

On the way to a totally integrated automation system not only functional process data are of importance. Nowadays, where increasing the efficiency regarding resource consumption of buildings and production plants is a big topic, centralised access to data provided by Smart Meters plays a significant role. This work presents first steps towards the integration of M-Bus-based metering devices into management applications in automation systems by means of OPC Unified Architecture.

Gebäudemanagement durch Wissensbasierte Systeme

Neben hocheffizienten Regel- und Managementstrategien gewinnen im Bereich der Gebaudeautomation Szenarien wie Laststeuerung und -verteilung, Energieruckgewinnung an Gebauden, die als Verbraucher und Erzeuger von elektrischer Energie agieren, an Bedeutung. Dasselbe gilt fur die Zustandsuberwachung zum Zweck der pradiktiven Wartung von Anlagen. All diesen Anwendungsfallen ist die Anforderung an ein gesammeltes und strukturiertes Wissen uber das Gebaude selbst, den aktuellen Betriebszustand seiner technischen Ausrustung, das Verhalten der Benutzer und externe Einflusse gemein. Die Fragestellung nach der Umsetzbarkeit eines solchen Systems soll in diesem Beitrag anhand einer Wissensbasis, die nicht nur statische Informationen uber die Gebaudetopologie und die Konfiguration von Automatisierungssystemen enthalt, sondern auch auf das aktuelle Prozessabbild der Gebaudeautomation zugreifen, diese verarbeiten und beeinflussen kann, bearbeitet werden.

Semi-automated engineering in building automation systems and management integration

Building planning as well as automation systems engineering involve numerous disciplines participating in a many-phase process. However, the information transitions between these different phases are mostly carried out manually which results in multiple sources of errors. Additionally, information which is already present is repeatedly manually re-entered during the whole workflow. This especially applies for building automation system engineering where on the other hand the majority of necessary information is already generated during the planning phase. To address this issue, this work proposes a workflow of semi-automatable engineering for building automation systems and also management gateway integration.

Modeling framework for IoT integration of building automation systems

Abstract Advancements within the Internet of Things are leading to a pervasive integration of different domains including also building automation systems. As a result, device functionality becomes available to a wide range of applications and users outside of the building automation domain. In this context, Web services are identified as suitable solution for machine-to-machine communication. However, a major requirement to provide necessary interoperability is the consideration of underlying semantics. Thus, this work presents a universal framework for tag-based semantic modeling and seamless integration of building automation systems via Web service-based technologies. Using the example of the KNX Web services specification, the applicability of this approach is pointed out.