Lars Dürkop

Using OPC-UA for the autoconfiguration of real-time Ethernet systems

In the future, production systems will consist of modular and flexible production components, being able to adapt to completely new manufacturing processes. This requirement arises from market turbulences caused by customer demands, i. e. highly customized goods in smaller production batches, or phenomenon like commercial crisis. In order to achieve adaptable production systems, one of the major challenges is to develop suitable autoconfiguration mechanisms for industrial automation systems. This paper presents a two-step architecture for the autoconfiguration of real-time Ethernet (RTE) systems. As a first step, an RTE-independent device discovery mechanism is introduced. Afterwards, it is shown how the parameters of an RTE can be configured automatically using Profinet IO as an exemplary RTE system. In contrast to the existing approaches, the proposed discovery mechanism is based on the OPC Unified Architecture (OPC-UA). In addition, a procedure to autoconfigure modular IO-Devices is introduced.

Performance evaluation of M2M protocols over cellular networks in a lab environment

According to the vision of the Internet of Things the seamless and flexible networking of everyday objects will become an important field of application for Internet-based communication. The simple integration of these devices into a communication system often requires wireless technologies, especially when there is no wired infrastructure available. Cellular networks of the third and fourth generation are promising enablers for embedding a variety of different devices into the Internet of Things. However, cellular networks use a completely different approach for data transmission and media access than wired networks like Ethernet. Therefore, it is necessary to investigate the transmission behavior of common protocols for machine-to-machine (M2M) communication with respect to the peculiarities of cellular networks. In this paper, three M2M protocols - CoAP, MQTT and OPC UA - are compared to each other with regard to their transport mechanisms to evaluate the transmission times and analyzing potentials for optimization. For the evaluation a laboratory test environment with cellular network emulators for EDGE, UMTS and LTE is used to analyze the protocols without interference of delays caused by the Internet or by other users allocating resources of the cellular network.

An analysis of real-time ethernets with regard to their automatic configuration

Future market conditions require production systems which can be easily adapted to changing demands. However, the engineering process of industrial automation systems is characterized by high manual configuration efforts. Thus, the reconfiguration of such system leads to time-intensive and expensive downtimes. Therefore, this paper will present a concept on reducing the engineering effort - at least on the lower layers of the automation pyramid. Due to the real-time requirements on these layers, specific communication technologies must be used there - for example Real-Time Ethernets (RTEs) which are increasingly applied in industrial automation. However, their real-time capability is contrasted by an additional configuration effort in comparison to standard networks from the information technology domain. This paper will show an approach for the automatic configuration of RTEs and will check its applicability on the most widely-used RTE variants.

A field level architecture for reconfigurable real-time automation systems

Rapidly changing customer demands lead to a paradigm shift from mass production to mass customization within the manufacturing industry. However, todays production systems are of a very static nature. Changing the manufacturing process requires a high amount of expensive human resources and is quite error prone. Hence, reconfigurability will become a key factor in the manufacturing industry and industrial automation systems must provide suitable solutions to support this new paradigm. Service-oriented architectures (SOAs) are a potential technology which can provide the requested capability of automatic reconfiguration. Originating from the IT world, the adaptation of SOAs to industrial automation systems has to face several difficulties - especially real-time requirements must be met. This paper proposes an innovative solution approach for the integration of a SOA into real-time systems for industrial automation.

OPC UA extension for IP auto-configuration in cyber-physical systems

The ability to remotely discover and configure devices in an automation network without the need for prior knowledge of the network topology or the identities of hosts and servers is a key requirement for industrial networks and cyber-physical systems. The Dynamic Host Configuration Protocol (DHCP) as a UDP-based standardized network protocol became very successful in computer networking and also to some extent in industrial networking, but it conceptually allows only device-initiated parameter assignment. This has led to the development of several other device configuration protocols that allow host-initiated device discovery and configuration. In this work, a survey on existing protocols is performed. Based on the results, a future solution is proposed as an extension of the OPC UA protocol suite. The proposal is able to meet the industrial needs for both device- and host-initiated operation with minimal invasive implementation.

Analyzing the engineering effort for the commissioning of industrial automation systems

In the industrial automation a paradigm shift from centralized, static automation structures to reconfigurable manufacturing systems (RMS) might be lie ahead. RMS are seen as a key enabler for the required changeability of future production companies since they can reduce the engineering effort needed for the reconfiguration of existing or the construction of new production systems. However, it is not clear how the companies can benefit from RMS in detail. For example, the reduction of engineering effort cannot be expressed in figures by today. But such information is necessary to convince the industry of the advantages of the new production principle. Indeed, existing RMS paradigms like Service-Oriented Architectures are rarely used in the practice of automation. The basis for analyzing the advantages of RMS is an analysis of the status quo in the industrial automation. Regarding the engineering effort of current automation systems, this paper will present a case study considering the effort occurring during the commissioning process of a production system constructed by state-of-the-art components. The evaluation of the study can serve as a reference when comparing the engineering effort of RMS with todays systems.

Übertragbarkeit des Plug&Play-Prinzips aus der Informationstechnik auf die Automatisierungstechnik

Die Inbetriebnahme von Automatisierungssystemen auf der Feldebene ist untrennbar mit einem hohen manuellen Konfigurationsaufwand verbunden: Feldgerate mussen in die Steuerungsapplikation integriert werden und die zur Vernetzung zwischen Feld- und Steuerungsebene eingesetzten Kommunikationssysteme mussen parametriert werden. In der Informationstechnik gibt es ahnliche Problemstellungen: So mussen Peripheriegerate uber einen Kommunikationsbus an einen PC angeschlossen werden oder in einem Heimnetz verteilte Gerate mussen miteinander interagieren. Hierzu gibt es etablierte Ansatze wie USB oder UPnP, welche dem Endanwender ein “Plug&Play” bieten, sodass er sich im Idealfall mit keinerlei Konfigurationsarbeiten befassen muss. In diesem Beitrag wird untersucht, wie “Plug&Play” (PnP) im Bereich der Informationstechnik realisiert wird und ob und ggf. wie sich diese Mechanismen auf die Automatisierungstechnik ubertragen lassen.

„Plug & Produce“ als Anwendungsfall von Industrie 4.0

Intelligente Fabriken sind das Ziel von Forschungsinitiativen wie Industrie 4.0 oder Industrial Internet. Aktuell werden vor allem Teilaspekte solcher Gesamtsysteme erforscht, z. B. Vernetzung, Energieoptimierung oder Selbstdiagnose. In diesem Artikel wird insbesondere das „Plug & Produce“ als Auspragung einer Selbstkonfiguration zukunftiger Automatisierungssysteme betrachtet, wobei ein Schwerpunkt auf der automatischen Konfiguration des echtzeitfahigen Kommunikationssystems liegt.

Coexistence of wireless control systems: An integral event-based simulation approach

Wireless control systems for factory automation (FA) applications are subject to coexistence impairments, especially in license-free spectrum bands. Evaluating the coexistence impact requires the knowledge of appropriate characteristic parameters and the usage of a suitable simulation method. In this paper we propose an integral approach for the event-based simulation of wireless coexisting close-loop networked control systems (NCSs) for mutual impact evaluations based upon the integration of an ordinary differential equation resolving library within an event-based wireless network simulation framework. The approach is evaluated within a harsh FA scenario of two identical closed-loop NCS with two coexisting wireless technologies IEEE 802.11 and PNO WSAN-FA.

Utilizing LTE QoS features to provide a reliable access network for cyber-physical systems

Cyber-physical systems (CPSs) are a new paradigm of control systems where control, communication, and computation fields intersect. Applications of such systems are expected to play an important role in many domains in the future. This includes critical domains such as transportation and health domains. Hence, it is quite important for such systems to operate reliably. Moreover, many CPS applications are characterized by having different modes of operation along with different corresponding traffic patterns and communication requirements. All this requires reliable communication networks that provide not only quality of service (QoS) support but also flexibility to adapt according to the varying communication requirements of the application/user. On the other hand, recent cellular standards such as Long Term Evolution (LTE) offer higher QoS control compared to earlier cellular standards with the ability to differentiate traffic at both the service and user levels. In this paper, we evaluate the ability of LTE cellular technology under certain QoS and load conditions to provide reliable communications for CPS applications characterized by possessing different modes of operation along with different corresponding traffic patterns and communication requirements. Our evaluation results indicate the ability of LTE cellular technology to provide reliable and adaptable communications for CPSs when QoS is provided.