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Über dieses Buch

Applications of communication networks lead to radical changes in human life. Fieldbus technology is part of this development acting in close connection to systems control and in critical domains. Equipped with sensitive sensors, fieldbus technology becomes the backbone of many processes of our daily life. In automation technology, fieldbus systems are essential parts of modern applications. In airplanes and in near future also in automobiles, mechanical control is replaced by "x by wire” systems based on fieldbusses, a technique more efficient and flexible, but also cheaper. Moreover, fieldbus technology, used in factories, hospitals, laboratories for the collection of numerous data, enables a more efficient and reliable operation of these complex environments. This book is a collection of articles submitted to the fieldbus conference FeT'99 in Magdeburg, Germany. The articles were reviewed by an international program committee which decided to include some high quality articles not presented at the conference. The book comprises chapters dealing with important aspects of fieldbus technology and reflecting areas of main activity in science and industry: real-time aspects, networking, management, OPC, system aspects, realization, protocol specifications (supplements to introduced fieldbus systems), validation, profile development (i. e. specification of application semantics) and research projects. A further chapter reports on the European harmonization project NOAH.

Inhaltsverzeichnis

Frontmatter

Protocol Specifications

Frontmatter

Main Paradigms as a Basis for Current Fieldbus Concepts

This paper discusses the main paradigms on fieldbuses from the applications requirements to the most common solutions derived to fulfill them. Temporal properties of the data to be exchanged are analyzed. Data are classified according to their criticality and their transmission frequency, for each of these types, the communication requirements are identified with emphasis on the realtime aspects. Two architectures are identified in order to design the applications, and an overview of their characteristics is presented. Main paradigms on fieldbuses are analysed at different levels of the architecture and in different contexts: synchronous vs asynchronous, periodic vs aperiodic, centralized vs distributed, static vs dynamic, deterministic vs nondeterministic. Several examples of the fieldbuses and the MAC protocols are analysed for each paradigm with regard to possible future fieldbuses.

Jean-Pierre Thomesse, Miguel Leon Chavez

Communication Profile for Embedded Networks

Embedded networks are used for machine or system internal communication between module and sub-systems. One of the most important embedded networks is Controller Area Network (CAN). In the early days of CAN, the embedded system designers have developed their own higher-layer protocols. Today, most of the system integrators like to use standardized application layers and communication profiles to reduce design efforts. CANopen is a family of specifications including communication profiles, frameworks, and device profiles for embedded networks based on CAN.

Holger Zeltwanger

Shared Data on InterBus

InterBus is a fieldbus system with cyclic operation making use of a total frame protocol. It is very well suited for real time applications. The additionally defined PCP (peripherals communication protocol) is designed for the exchange of numerous data without hard real time demands, eg. parameters and program downloads. “Shared Data” is a new approach presented in this paper which enhances the features of PCP. It offers a data channel on InterBus generally useable both for tasks similar to PCP and for temporary real time connections among a small number of partners. The shared data channel allows data transfers marked with specific transfer codes directing data to a predefined number of modules. An immediate read out of data of modules is possible as well as a transfer of multiple data within the same execution cycle.

H. Schweinzer, W. Kandler

Adding Multi-Master Capabilities to Interbus-S

Fieldbus technology is achieving more and more attentions throughout all the different sectors of industrial automation. They were born as local area networks dedicated to applications in the area of data acquisition and control of sensors and actuators inside the factory. Nowadays there are many fieldbus systems commercially available, and each of them is peculiar for particular kinds of applications. In this scenario the Interbus-S system is playing the role of a main character. Born under the name of the ‘sensor-actuator’ bus, it has been appreciated by control systems designers and technicians essentially for two important qualities. Firstly, the reliability of its open-architecture, being supported by a variety of products coming from different manufacturers. Secondly, for the efficiency of its own protocol, that makes it a very interesting suite for real time applications. Notwithstanding, the architecture suffers the centralization of the mono-master arbitration scheme, which make it unsuited for a wide range of applications. Maintaining full compatibility with the existing standard, we have studied, defined and implemented a protocol extension which overcomes these limitations and makes it ready for new scenarios.

Salvatore Cavalieri, Antonio Consoli, Orazio Mirabella

Telecontrol Standard IEC 60870-6 TASE.2 Globally Adopted

The Information exchange has taken on increasing importance for the restructured energy industry. A standard communications protocol that powers this information exchange, even between incompatible communication systems, enables improved system performance, often accompanied by dramatic cost savings. Developed collaboratively by a team including energy companies, vendors, and EPRI, the Telecontrol Application Service Element or TASE.2 (EEC standard 60870-6 TASE.2 — also known as the Inter-Control Center Communications Protocol or ICCP in the United States) facilitates seamless exchange of time-critical data over local and wide area networks. TASE.2 is the most capable, widely adopted open communications protocol available to the electric power industry today. TASE.2 defines open functions and an object model for application data. TASE.2 supports the integration of instrumentation and control into the corporate wide information and data processing in any application domains, e.g., utilities, manufacturing, or process control.

Karlheinz Schwarz

Network Interconnections

Frontmatter

Opportunities and Problems of Wireless Fieldbus Extensions

Many examples are known for the influence of technologies, originally made for consumer market, to industrial automation. The digital wireless communication technologies, mostly used for mobile telephony, are one of the most rapidly growing branches today. This paper shows that there is an actual need to introduce this technologies to the industrial automation. Many cases can be listed where today widely used fieldbus systems advantageously can be extended by wireless components. But the requirements of these different communication systems are very different as discussed in the paper. Radio technologies are introduced and a scenario is discussed which uses DECT to extend Controller Area Networks. Opportunities and problems of wireless fieldbus extensions are shown.

Lutz Rauchhaupt, Jörg Hähniche

The Use of Radio Technologies in the Fieldbus Area -Using INTERBUS as an Example

Until recently, data transmission by radio in the fieldbus area was inconceivable. The available radio technologies were too susceptible to interference, cumbersome, expensive and slow. However, new radio technologies such as DECT or the 2.4 GHz ISM band used in 802.11 offer promising new possibilities for fieldbus links which were only previously made possible using costly connection technology. This offers the user both straightforward installation and a higher degree of flexibility, without increased costs. Through the joint project supported by BMBF (German Federal Department of Education, Science, Research and Technology), “Wireless Fieldbuses in the Production Environment” (FUNBUS), and cooperation with the technical college FH-Lippe, initial experiences of using radio technologies on Interbus have been collated from various viewpoints and a product-related prototype has been developed for use on Interbus.

Michael Peter

Internet Technologies and Fieldbuses

Facing the rapid changes brought in the industry automation world by the wide spreading of Internet technologies, this paper describes what will be the impact of the use of the internet technologies as an improvement of the facilities that were initially brought by fieldbus at the lower levels of the industrial control systems.

Thierry LaÎnÉ

Security Architecture for Field Area Networks Connected to Internet

It is already a reality that data security aspects start to play a dominant role almost in every fieldbus application. Most of all, it concerns fieldbus- Internet applications. The major goal of this paper is to propose and to describe a security architecture for such applications. The papers covers its main concepts and implementation basis. An undivided attention is paid at standardization and conceptual issues. The paper does not provide an universal solution, which can be directly applied to an application of any kind. It focuses at major concepts and guidelines, which should lead to secure fieldbus-Internet applications.

Mikhail Gordeev

P-NET-Management über das Internet

For the interconnection of fieldbus systems and IP-based LANs, a gateway is required. A reasonable implementation approach is to split the gateway into two parts. One part then takes care of the SNMP protocol, while the other handles the actual communication with the fieldbus. This article describes the implementation of the fieldbus specific part for P-NET, a fieldbus specified in the European standard EN50170. The implementation uses the Windows-based software VIGO as a fieldbus driver. An approach for the configuration of the gateway is also presented.

Melih Ayal, Martin Knizak, Thilo Sauter

Wireless Data Transfer System for Oil Drawing Plants

The present work describes the design and building of a data transmission system for Collector Centres monitoring and automation in an Oil Drawing Enterprise in Cuba (EPEP). Packet-radio modems were used, working in the VHF bands at 1200 and 9600 bits per second, resulting in an economic solution. This data transmission system is a wider and modem version of the previously developed at 1994 by the authors. The system goal is automatic transfer of files and data collected by instruments, from several oil drawing centres, to the computer network located in the headquarters building. This task is done without interfering with other applications normally executing in these plants. The new system runs in multitasking environments such as Windows95 and WindowsNT.

Angel Alonso Perez, Vitalio Alfonso Reguera, Felix Alvarez Paliza

Profiles

Frontmatter

Profiles for Fieldbuses - Scope and Description Technologies

After years of distributed protocol specifications the added value for end users in terms of more functionality e.g. for diagnosis and maintenance becomes topic more and more. The question which functions of the field devices can be used in a similar standardized way as communication services is of interest instead of the question, how data are transferred. So the fieldbus organizations offer profiles on top of the communication protocols. The state of the art of specifying profiles is described. In the profile specification the field device is seen as a stand alone component not as part of a distributed control system mostly. This results in high efforts for the integration of field devices in the all over life cycle of the distributed system. Therefore the paper offers an approach, how field devices are reflected as system components during the specification work, and how implementations of devices and tools can be derived from the specification. These specification method is based on the Unified Modeling Language (UML).

Christian Diedrich

A Functional Profile for Laboratory Measurement Equipment Based on Measurement Bus and Profibus-DP/PA

A new functional profile for labaroratory devices is the result of a working group “Laboratory Data Communication” in the Standardization Committee “Laboratory Devices and Laboratory Equipment” of DIN. Based on a very complex functional profile for process devices (Class A) of the Profibus User Organisation (PNO), a set of only seven simplified function blocks have been proposed, wich meets the main communication requirements of low-cost laboratory devices. Two fieldbus systems are elected for the necessary transportoriented communication services: Measurement Bus (“DIN-Messbus”) and Profibus-DP/PA. All function blocks and its defined variables will be mapped on the specific application services of these two bus systems.

Ulrich Wagner

Mapping of Fieldbus Protocols to Standardised Field Level Objects

The specification of the Field Level Object standard is finished and the corresponding European pre-standard will be published at the end of 1999. In this paper the mapping of a fieldbus communication system to the objects, functions and services defined in the pre-standard is presented. As an example the EIB system is used for which a detailed mapping guide as annex for a draft of an European pre-standard exists. The mapping is shown in detail for the analogue object explaining some of the mapping problems.

Peter Fischer

Device Based Process Control in Foundation Fieldbus

Devices based on the Fieldbus Foundation’s specification will, as an integral part of their design, allow process inputs and outputs to be precisely sampled by the device without aliasing or skewing. Fieldbus Foundation also standardizes a device description language (DDL) in which device manufacturers can present a description of their field devices. Given these standards it became possible to distribute function block control technology to fieldbus devices of different vendors. An overview of monitor, control, and diagnosis techniques used in Foundation Fieldbus is presented. Also, the manner in which fieldbus may influence advanced control implementations, such as process identification for controller self-tuning is reviewed.

Dirk Thiele, Terry Blevins, Willy Wojsznis

CANopen Device Profile for Hydraulic Proportional Valves

The trend towards decentralized concepts in fluidic systems requires effective communication structures between the networked components. Fieldbusses are designed to meet these requirements. When using similar devices from different vendors, a harmonization concerning communication objects and devices’ behavior has to be reached in order to minimize efforts in design and configuration of the whole system. Thus, a bus-system independent device profile for fluidic components has been defined. This profile has been mapped to CANopen. The article describes the profile and the CANopen mapping and the description technique used.

Martin Wollschlaeger, Erik Unger, Heiko Witte

Validation

Frontmatter

Comparing the networks CAN and ARINC 629 CP with respect to the quality of the service provided to an automatic control application

The objective of this work is, at first, to formally model and evaluate the Quality of the Service (delay) provided by the MAC layer of the networks CAN and ARINC 629 CP with respect to a particular periodic message stream among a set of periodic message streams and, second, to link this Quality of Service to the stability performance of a closed loop control system which is based on this particular periodic message stream. At first, the message scheduling and delay evaluation are made by using Stochastic Time Petri Nets. We show the relation (message priority - message delay), and when either CAN or ARINC is better. Finally, by considering the closed loop control system as a continuous linear system and then using the concept of transfer function based on the Laplace Transform, we evaluate its phase margin in function of the delay.

I. Blum, G. Juanole

Modelling and Evaluation of Systems for the Interconnection of Industrial Communications Networks

The aim of this paper is to tackle issues regarding interconnection of Industrial Communications Networks. For this purpose, two interconnection strategies are presented and applied to a widely used fieldbus standard: Profibus. The adaptation of Profibus to the so called Extended Fieldbus is investigated and an extended address scheme for Profibus is proposed. A brief description of the developed models, focusing in the interworking unit, is given together with the verification and evaluation methodology followed. Finally, some performance results are presented which are used to compare the two interconnection strategies.

Víctor M. Sempere Payá, Jorge Mataix Oltra, Estanislao Utrilla Ginés

Use of Formal Specification and Design Language for Protocol Description - Field Report -

Due to the growing demands placed on fieldbus systems, continuous development of protocols is required. Since it is becoming difficult to ensure consistency because of the increasing complexity of specifications based on informal text, the formal specification language SDL has been used in the current project. The experiences gained in relation to changes in the development cycle through the use of a formal specification language are described. The link between SDL and MSC, and its strengths and weaknesses are illustrated. The options for verification through simulation are introduced.

Matthias Prüβner, Aykut Gemici

CANopen Conformance Test

Conformance tests are used to guarantee that different products can work together. For that reason there was founded a group which defines a test procedure for CANopen devices based on the CANopen Communication Profile DS301 V3.0. This test procedure will guarantee that CANopen devices can communicate on the bus, the default values are set correctly to the standard and the network state machine is correctly implemented.

Thilo Schumann

Formal Description Software for WorldFIP Industrial Fieldbus

In this work the protocol WorldFIP for industrial communication networks, is specified with the formal specification language LOTOS. This specification is the foundation of new work lines such as efficiency analysis of WorldFIP performance with simulations in critical applications, the generation of benchmark patterns for conformance tests of WorldFIP communications equipment, and the proposal of new advances in the fieldbus area. The paper introduces the general characteristics of LOTOS, and the main features of WorldFIP particularly the related with its data link layer. Also the methodology and used tools are explained, and results and new guidelines of this work are quoted in last paragraph devoted to conclusions and future works. LOTOS specification of WorldFIP protocol provides powerful CAE tools for advanced designs in the framework of industrial communications.

Perfecto Mariño, Miguel Angel Domínguez, Francisco Poza, Juan Nogueira

Experiences in Different Fieldbuses Used together with PC-Based Control Systems

This paper deals with experiences about three different fieldbuses based on a comprehensive research study in the field of PC-based device and system control (soft PLC). The research has been made in Tampere University of Technology at the Institute of Production Engineering. The overall reaction time of PC-based control systems has been tested so that the delay caused by fieldbus is included. For the end user this is the reaction time that counts. The paper discusses also some topics concerning motion control and a case study of an application controlled by soft PLC.

Ville Saarimäki, Niko Siltala, Petri Partanen, Jorma Vihinen, Reijo Tuokko

Management

Frontmatter

Mapping of Fieldbus Components to WWW-Based Management Solutions

The seamless integration of fieldbusses into enterprise wide communication systems enables a network centric approach to fieldbus components’ management. This requires the mapping of fieldbus components and their functionality to WWW-related management solutions. Therefore different strategies are suitable. Developments in software technology allow the introduction of new concepts for management tasks of fieldbus based components. Besides the software oriented tasks, there are new description techniques that can be used in fieldbus systems. WWW-related management solutions for different systems are described in this paper.

Martin Wollschlaeger

Integration of Fieldbus Objects into Computer-Aided Network Facility Management Systems

Although currently there are several activities that are focused on a unified way to project and administrate fieldbus systems the planning and management of these systems in the sense of a comprehensive infrastructure is not possible yet. In this paper an approach for the integration of Building Automation Systems using different fieldbus systems into the technical Facility Management shall be demonstrated. This integration is realized using standardized mechanisms like OPC technology and common object definitions for different fieldbus systems based on international standards. The paper gives an introduction into the basic models and introduces a way to solve this task.

Thomas Bangemann, Ralf Dübner, Arne Neumann

Enabling e-Services through Resource Management API’s on Multi-Vendor EIB Building Networks

Appropriate standardization of network resource management is a prerequisite for accessing this same functionality remotely, e.g. via Internet. In turn, this enables all kinds of e-services such as remote diagnostics and maintenance of building control networks — these can be offered on a commercial basis and constitute new markets for professional contractors and system integrators. On an open multi-vendor network (with multiple system implementations from several system providers and based on different microprocessor families) such as EIB, some degree of polymorphism has to be taken into account to cover variations in implementation. Defining the abstract methods for resource management requires some clever modeling. This contribution investigates the procedural modeling techniques which may be successfully applied. Once established, these methods can be mapped to Network Management API’s for configuration tools, management stations and e-services.

Marc Goossens, Heinrich Reiter

Modulares Agent-Design für Feldbusmanagement

An interconnection between fieldbus systems an global networks (including also the Internet) opens new possibilities for remote access to data in automation systems. A good basis for such a combination are the methods and protocols known from the management of IP based networks. The actual access is provided by an appropriate gateway. We suggest a modular approach to divide the gateway into an Internet- and a fieldbus-specific part. This concept is appealing in that it is largely platform independent and allows for the distribution of the modules in a network. Furthermore, one gateway can also serve more than just one single fieldbus system.

Ronald Haidvogl, Martin Knizak, Thilo Sauter

Linux-Gateway zur Fernwartung von Profibus-DP-Geräten

Abstract Since its humble beginnings Linux has grown from strength to strength. On one hand it has evolved into an operating system for business, personal productivity and education, on the other hand it is an ideal platform for software developers. Since in our opinion Linux’s breakthrough in factory automation is imminent we decided to implement the worldwide first Linux device driver dedicated to fieldbus systems: a Profibus-DP driver. This paper presents the device driver’s implementation and its application programming interface and shows one possible application rest upon it: a network interconnection from Profibus-DP to the Internet using a Java-based gateway.

Wolfgang Kastner

Tele-Diagnosis at Networked Automation Systems

This paper describes a teleservice — tool, which is used for the remote diagnosis of PLCS at machines. It records the operations in the interior of the PLCS. Thereby all real time — details are measured. To be able to select the measured variables flexibly, a mobile agent is constructed in the far computer. This agent will transfer into the PLCS with the help of the network and begins to work there. The observations at the software are supported by video — and audio — measurements at the machine.

Klaus Kabitzsch, Volodymyr Vasyutynskyy

Diagnose von Feldbussen im Systemverbund

Embedded Systems are becoming more complex. As both software and hardware become more complex, debugging and testing consume higher proportions of the development budget and project time. The PRACTICAL tools offer one way to reduce this.The PRACTICAL tools focus on CPU independent hardware assisted debugging tools for embedded systems, both for single CPU systems and for distributed systems. The architecture separates the debugging environment into three groups: GUI (display) and analysis engines, Debugging heads, Targets being debugged. The first two groups are connected via Ethernet and TCP/IP, whereas debug heads are connected as required by the target hardware. All the tools are independent of the target CPU, providing an alternative to the ever increasing cost of In Circuit Emulation as CPU speeds increase.Debugging hosts may be any standard PC or Workstation. PRACTICAL tools take advantage of the universal availability of Ethernet connections to allow a wide range of hosts to be connected simultaneously. These hosts may cover simple functions such as target program generation, debug head control, target node simulation and I/O simulation control.The debugging heads will be programmable by the user, using portable applications, so permitting the wide variety of debugging requirements to be satisfied by a range of small applications held on the debugging host and downloaded as required to the debugging heads. Debugging heads may include device simulators for I/O timing analysis, program loaders, CPU debug access via JTAG or BDM, fieldbus network analysers.

W. Kriesel, T. Heimbold, Th. Minner

Engineering of Distributed Automation Systems Based on Novel Information Technologies and Methods

Hard economical conditions in the Automation and Process Control Industry are making secondary processes as Product Data Management and System Engineering more and more important. The following report describes a method, developed and realized as prototype by the BriteEuRam Project Advanced Control Network (ACORN 1479), which is used for the engineering of automation systems, and based on standardized description methods.

René Simon, Jörg Hörger

PROFIBUS goes Microsoft - Herstellerunabhängige Integration von Feldgeräten in Engineeringsysteme

With the integration of fieldbusses into existing systems are some tasks, that still wait for completion. This is valid for fieldbusses in general. The following article will show this at the example of PROFIBUS in special. The integration of field instrument configuration-tools with engineering interfaces, that could be used by all vendors in the plant, is very important. This is especially true for large and heterogeneous plants in the process industry. To resolve this task, the control systems and instrument vendors founded a working group in the ZVEI (German manufacturers association) to develop in close contract with the PNO (PROFIBUS Users organization) a vendor neutral solution. Main target of this activities is the specification of a software-interface. This interface should easy to implement for the field instrument manufacturers as well as for the DCS vendors.

Harald Bruns, Ulrich Hempen, Wolfgang Ott, Rolf Vahldieck, Karl-Heinz Niemann

OLE for Process Control OPC

Frontmatter

A Modular OPC-Server Connecting Different Fieldbussystems and Internet Java Applets

The standardization of the interface between the office and the field level becomes more and more important in automation systems. In this paper a modular OPC-Server is presented, that combines two features. First, an application software on office level has to be connected to only one server, even if it needs data connections to different fieldbusses. And second, fast and efficient communication between different fieldbusses is possible. Furthermore an OPC-Client is implemented, that is also a Web-Server with Java RMI functions (Remote Method Invocation). Combining the OPC-Server with the OPC-Client results in a system, that enables data access from a standard PC with a Web-Browser into several different bussystems on field level.

S. Rüping, H. Klugmann, K.-H. Gerdes, S. Mirbach

OPC-Schnittstellen in einer offenen Systemumgebung - Praxis und Erfahrungen

The paper represents any results of a research about usability of OPC interfaces within an open system environment. The hardware and software platform for this works is a plant model using a lean communication structure which is being built up since 1999 at the process control lab of the University of Applied Sciences in Düsseldorf. The results of this works show that OPC interfaces provide quick installation procedures and safe operation. Currently available OPC interfaces are suitable to meet the timing requirements for a process data communication between visualization/supervisory systems on one side and fieldbus/control systems on the other. However, the application of an OPC interface requires a sufficient knowledge and experiences in PC and Windows technology.

Reinhard Langmann, Arnd Groppe, Viktor Ossipov, Norbert Stuhrmann

OPC - Making the Fieldbus Interface Transparent

The performance of fieldbus systems has been studied more or less thoroughly. With the advent of high speed fieldbus systems as PROFIBUS-DP the bottleneck of systems moves from the communication to the application, especially to the interface between both. Two requirements are placed on such interface in general. First it should be based on an open, accepted standard where secondly it should support real-time operation. As the PC becomes more and more important even in the realm of industrial automation the quality of interfaces based on Microsoft Windows technologies gains importance too. The first solution provided with Windows 3.1 was the Dynamic Data Exchange (DDE). Although an open an finally widely accepted standard its communication performance was not satisfactory. The development of the OPC (OLE for Process Control) architecture aimes at solving the question of performance while providing an open interface standard between applications. Although the openness of this solutions is not debatable, the performance issue has to be investigated. This paper contributes to this by exploring the performance of an implementation of the OPC interface standard.

Thomas Hadlich, Thorsten Szczepanski

System Aspects

Frontmatter

IEEE Utility Communications Architecture (UCA) applies mainstream standard Ethernet

The Utility Communications Architecture (UCA™) is a standardsbased approach to utility communications which provides for wide scale integration at reduced costs, and which solves many of the most pressing communications problems for today’s utilities. The UCA is designed to apply across all of the functional areas within the electric, gas, and water utilities. These functional areas include customer interface, distribution, transmission power plant, control center, and corporate information systems. The UCA includes detailed object models, which defines the tag, format, representation, and the meaning of utility data. This modeling effort goes far beyond the scope of any other utility communications approach, and provides for an unprecedented level of multi-vendor interoperability applicable in most industries.

Karlheinz Schwarz

A Component-Based Architecture for Integrating Fieldbus Systems into Distributed Control Applications

This paper presents a novel software architecture for the easy and complete integration of fieldbus systems into complex distributed control systems. A combination of well-established technologies with a new componentbased approach results in a powerful system architecture suitable to meet today’s user requirements. Our architectural concepts allow the rapid, compilerless development of efficient applications for fieldbus-based process control and visualization. Moreover, the assembled application may easily be adapted to changing process or operating requirements during runtime without interrupting active control tasks.

R. Bachmann, M. S. Hoang, P. Rieger

Decentralized automation concepts based on Ethernet-TCP/IP and CANopen

The advantages, which decentralized automation will make available to the machine and plant designer, are still to be seen. In discussion is a solution that can be realized now because the necessary components and technologies are all readily available, such as: Ethernet-TCP/IP, CANopen, industrial-compatible rail mounted PCs, OPC and IEC 1131-3.

Andreas Ziegler

Considerations on a LonWorks/IP Gateway Implementation

The success of the Internet makes it a superb goal to discuss interworking aspects with fieldbus systems. LonWorks with its strict layering is especially interesting to explore within this context. The discussion of concepts for a LonWorks/IP gateway leads to three approaches exploiting different protocol mechanisms giving IP hosts access to nodes’ files, network variables and application messages as well as EIA-709.1 link layer packets. An experimental implementation is based on a real-time operating system running on an embedded hardware platform featuring a powerful Motorola micro controller.

Stefan Soucek, Hans-Jörg Schweinzer

The Importance of Being Competent: the Role of Competence Centres in the Fieldbus World

As far as their application in practice is concerned, fieldbus system are still a new technology that many potential users are not quite aware of. Competence centres can provide such users with know-how and thus help to improve the acceptance of these new concepts. This article presents an overview of the services a competence centre can provide, with a particular emphasis on training activities. We shall also describe a European project dedicated to the establishment of new competence centres in the countries of Central Europe.

Thilo Sauter, Max Felser

Research

Frontmatter

Some Future Directions in Fieldbus Research and Development

In this paper, we attempt to explore the different topics where there still exist opportunities for research and development in the fieldbus domain. Different venues are explored and the main problems are outlined. References to on-going work are given.

J.-D. Decotignie

IEEE1394 in Comparison with Other Bus Systems

IEEE1394, also known as FireWire™, is a relatively new high performance serial bus system. It was originally designed to connect multimedia devices, but due to its properties it can also be used for other applications, e.g. for industrial automation. In order to consider the use of IEEE1394 in combination with or instead of traditional and established communication systems, it is necessary to have comparison values. This paper shall point out these pros and cons of IEEE1394 by comparing it with field area networks and Ethernet.

Norbert Stampfl

On Interoperability and Intelligent Software Agents for Field Area Networks

Intelligent software agents are software programs that are currently used to solve complex problems in the domains of network management or information retrieval. The usage of agent technology for field area network would offer a lot of new and enhanced applications and would be “the second chapter” of distributed applications. The missing link to the commercial exploitation of agent technology on field area networks is a standard for agent communication. This paper gives an overview and takes the first steps towards standard agent communication for field area networks.

Peter Palensky

Transmitting Voice on InterBus

This paper presents requirements and solutions for speech communication via InterBus. Using an appropriate data compression algorithm the data rate of speech does not exceed rates of conventional InterBus applications. By using standard InterBus slaves the cycle time increases according to the number of InterBus Voice Stations. By connecting several speech stations the system is soon overloaded. In a more effective solution a specified data area of the total frame of InterBus is used. This data area is called “Shared Data” channel and is alternately used by all speech stations. In this way few flexible connections can be established without overloading the system.

W. Kandler, H. Schweinzer

Real-Time Aspects

Frontmatter

Simulation of Communication Systems in Industrial Area

The large assortment of networks used in industrial area (e. g. field-buses, LANs and telephone systems) calls for computer based tools for modeling and simulating their performance. This paper presents such a tool, which is implemented in a communication-protocol independant structure to determine the usability and efficiency of different networks. Furthermore it allows not only evaluating the improvements of classical factory communication systems, but also analysing the introduction of complete new systems for factory applications.

Detlef Bäuerle, Wolfgang Popp

A Flexible Time-Triggered Communication System Based on the Controller Area Network: Experimental Results

Controller Area Networks are normally used in event-triggered communication systems. These are known for not supporting composability in respect with the system temporal behavior. When using a time-triggered communication paradigm, such composability is achieved. However, common time-triggered systems rely on static message scheduling which compromises system flexibility. This paper proposes the use of centralized scheduling together with a planning scheduler to achieve flexible time-triggered communication on a CAN system. A model is deduced to allow the prediction of message production delays for a particular implementation using low processing power microcontrollers (Philips 80C592). Experimental results shown confirm the validity of the model. These results are also in agreement with a model for the scheduler execution time presented by the authors in previous works concerning the use of the planning scheduler in FIP-like networks.

Luís Almeida, José A. Fonseca, Pedro Fonseca

Analysis of Switched Ethernet Networks with Different Topologies Used in Automation Systems

Ethernet is the most famous type of communication network used for office applications. Currently, networks used on field level and on office level are different due to their specific requirements. Especially for real-time systems, the deterministic behavior of the network is very important. Now Switched Ethernet seems to be applicable also on field level, because collisions can be avoided and priorities can be used. In this paper Switched Ethernet networks with different topologies are analyzed concerning the transmission delays. Therefore a typical master-slave scenario of an automation system is investigated.

S. Rüping, E. Vonnahme, J. Jasperneite

Analysis of the Worst-Case Real Token Rotation Time in PROFIBUS Networks

This paper provides a comprehensive study on how to support time critical distributed applications using PROFIBUS. We show that, despite the absence of synchronous bandwidth allocation, it is possible to guarantee real-time behaviour for the high-priority traffic in PROFIBUS networks. The main contribution of this paper is to give a methodology for the setting of the T TR parameter, by proper analysis of the worst-case real token rotation time (T RR ).

Eduardo Tovar, Francisco Vasques

Realisations

Frontmatter

Powerline Communication in der Feldebene

Present a consequential standardization becomes generally accepted for fieldbus networks. Each of the available network solutions is shaped by a typical communication standard, that optimally employable is for special application areas. Existing industrial solutions establish themselves with it more and more strongly and hardly still appear it new networks. By optimization of the network structures and expansion of the application width innovations are advanced. The realizations of new designs of the physical interface of field bus networks contribute to it particularly. With the aim, through new circuits the original bus node interfaces to expand, the application-width of the respective field bus is rising. For the data transfer the field bus networks use different physical media. To the expansion of the utilization some research projects concentrates of the bus integrated power supply. Important technical and economic effects through simultaneous transfer of information and energy over the same wire can be achieved.

Helmut Beikirch

Design of Bus Media Redundancy in CAN

Network media redundancy is a clean and effective way of achieving high levels of reliability against temporary medium faults and availability in the presence of permanent faults. This is specially true of critical control applications such as those supported by the Controller Area Network (CAN). This paper deals with the complexity of implementing bus media redundancy in CAN, discussing how this can be done through a simple scheme that uses inexpensive off-the-shelf components.

José Rufino, Paulo Veríssimo, Guilherme Arroz

Programmable Process Interfaces for Smart Bus Nodes

In Field Bus Systems intelligent functions are more and more shifted to the sensors. For the realization of these functions a powerful decentralized electronics is required directly at the sensor. At present extensive activities run to realize these intelligent functions near to the sensor. Such intelligent sensor systems in serial industrial networks are called Smart Bus Nodes. They are efficient low cost bus nodes combining an extensive software functionality with a very low power consumption. They are able to communicate on a higher OSI layer and to execute signal processing functions independently. A configuration of the process interface with the present circuit design possibilities can be done with analog multiplexers and programmable amplifiers. For the preparation of solution ways, we have in the last time the possibilities programmable integrated analog and digital Interface Circuits investigated.

Helmut Beikirch, Matthias Voβ

Eine Feldbusarchitektur mit realzeitfähiger Fehlerkorrektur

This article describes a fieldbus architecture particularly designed for real-time applications in which the runtime performance cannot only be determined a priori, but also controlled during the entire process duration. Basically, it consists of a dual ring bus, in which two telegrams are transmitted on both channels in opposite directions, thus making delay measurements feasible. Even in the presence of strong disturbances on the transmission channel, the signal coding by a modified “Frequency Shift Keying” method enables the receivers to securely recognize the input signals. By additional Hamming encoding of the telegrams, in each receiver an error correction is possible without requiring repetition of transfer.

Thomas Erdner

Safety-Oriented INTERBUS - INTERBUS Safety -

The use of bus systems in automation technology has led to considerable savings, of which many companies are beginning to take advantage. This is also the reason for the increasing acceptance of fieldbus systems e.g., by automotive manufacturers, who now specify fieldbus networking as a prerequisite when planning a new system. However, one area has remained largely unaffected by these rationalization options. Safety technology is only gradually being implemented using transmission systems; however, the demand for this can no longer be ignored. It will soon be possible to implement safety-oriented applications using INTERBUS. INTERBUS is aiming to reach Category 4 (Cat. 4) according to EN 954-1.

Karsten Meyer-Gräfe

MultiPort RAM: a PC-Based Implementation of the Fieldbus Concept

The rapid introduction of industrial personal computers into the manufacturing automation throughout the last years gave an increasing importance to the PC-based distributed automation systems. One such system is MultiPort RAM, a software package which implements the conventional fieldbus concepts while running on a standard personal computer architecture. The paper reviews a general structure of this system, it’s functionality, operation principles, and application development aspects. The networking implementation is investigated in detail. Finally, a methodology for the MultiPort RAM integration with other field and wide area networks is discussed.

M. Lobachov, T. Sauter, B. Plagemann

Fieldbus Physical Layer in the Application

A major characteristic of automation technology is a strong growth in the market for network components which are responsible for the fault free transmission of data. The range of network components for fieldbus applications pass from the simple copper connector over fiber optic fieldbus repeaters up to hubs for ETHERNET. This article will show the advantages of new technologies for communication and connection. The two major technologies which are discussed are fiber optic fieldbus networks and high speed connector systems. High speed means in this case very short installation times. Also developements for the future like ETHERNET for industrial networking are shown.

Udo Fetzer

NOAH Esprit 26951 Project

Frontmatter

ESPRIT Project NOAH — Introduction

The ESPRIT Project Network Oriented Application Harmonisation (NOAH EP 26951) specifies and validates important parts of on open platform for distributed automation systems.

Udo Döbrich, Patrice Noury

Fieldbus Profile Harmonization — Approach of NOAH ESPRIT 26951 Project

The NOAH (Network Oriented Application Harmonization) project harmonizes device profiles of the EN50170 fieldbusses WorldFIP, P-Net and PROFIBUS among others. Within the project a certain subset of field devices are under consideration. The investigations cover transmitter for temperature and pressure, on/off and modulated actuators, simple I/O, motor control centers and variable speed drives. The range of devices shows, that basic device classes with very different scope and functionality are chosen to find fieldbus and profile independent application structures, functions and parameters. The project follows a well defined device model for the harmonization. The common parts of all profiles are presented and the consequences are discussed.

H-P. Otto, Ch. Borodino, T. Bregulla, Ch. Diedrich, U. Döbrich, J. Hörger, J. Szymanski, Ch. Verney

Electronic Device Description

Engineering costs are becoming more and more dominating in the complete live cycle of automation systems, especially under a true cost-of-ownership principle. Electronic Device Descriptions are a good means to reduce the engineering costs. The following report presents the history of Electronic Device Descriptions and describes the method and technology, developed by the ESPRIT Project “Network Oriented Application Harmonisation” (NOAH).

René Simon, Claudio Demartini

A DBR-Based Approach for System Management

This work describes the Database Repository (DBR) as specified within the ESPRIT Project “Network Oriented Application Harmonization” (NOAH). The DBR provides a uniform solution to support the control, configuration, management and maintenance of industrial plants. The basic aim of this approach is to define a general information model that can describe any distributed automatic system. The Database Repository specification unifies the actual representation of the devices within complex systems allowing heterogeneous devices and their links to be described according to a common approach, regardless of their specific implementation.

C. Demartini, R. Iosif, C. Raibulet, J. P. Thomesse

NOAH Project: an Example of Application

A NOAH demonstrator is planned in the IAM Pilot based at ENEL Ricerca’s premises in Milan. The IAM Pilot is the result of ESPRIT projects funded by the European Commission, and is a cooperative action of ENEL with the User support Groups for automation based on CENELEC EN50170. It is a permanent platform used to investigate research results, standards and market offerings for distributed automation. The paper describes how the IAM-Pilot laboratory, already equipped with EN50170-compliant instrumentation, has been upgraded to implement an example of the NOAH architecture. This experimental site is intended to enable us to bring together some key concepts of the NOAH project (which are explained in the other papers presented at this Conference) and will permit us to show, concretely, how main NOAH concepts may be brought to bear to obtain the expected results. The paper recalls the IAM-Pilot structure and investigation approach and describes the general demonstration scenarios developed for NOAH. Particular attention is paid to the practical aspects of the possible use of the NOAH concepts and to verification of the real benefits end users and system integrators can derive from the Noah approach. Another key expected result from a real practical investigation is the possibility of checking the key aspects of the NOAH specifications in order to submit verified specifications to CENELEC with a view to drawing up a suitable standard.

Antonio Mella, Francesco Russo
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