Authors: Jerome Ermont; Jean-Luc Scharbarg; Christian Fraboul

Abstract: Increasing communication needs of embedded systems lead to the integration of switched Ethernet, in order to bypass the bandwidth limitation of classical fieldbuses. This paper propose the use of timed automata and model checking in order to analyze the timing behavior of a network architecture including specific fieldbuses (CAN, FIP,...) interconnected by switched Ethernet. The architecture is decomposed into basic components modeled by timed automata. The modeling of the overall architecture is obtained by assembling basic components. Model checking then exhibits for instance worst-case delays scenarios.

Keywords: switched Ethernet,fieldbuses,time automata

Identifier: 10.3182/20071107-3-FR-3907.00035

Conference: 7th IFAC International Conference on Fieldbuses and Networks in Industrial and Embedded Systems (2007)

Location: Toulouse University, France

Start Date: Wed Nov 07 2007 - End Date: Fri Nov 09 2007

Authors: Cesare Bartolini; Giuseppe Lipari; Luis Almeida

Abstract: The CAN bus, highly appreciated for its efficiency and low cost, is widely adopted in many fields, especially where real-time properties are required. However, it is particularly tailored for short data, supporting up to eight data bytes per frame. Larger data entities need to be fragmented so that they can be transferred over the network. Such fragmented messages may experience long delays caused by preemption by higher priority messages, even when these still exhibit slack. This problem has been found in lift control systems in which multiframe CAN messages had to be sent regularly and were also subject to timing constraints. This paper shows how to use current analysis to deduce response times for multi-frame CAN messages and then it proposes using resource management policies in the CAN bus, namely the Priority Inheritance Protocol, to exploit the slack of higher priority messages and reduce those response times. The paper presents several results that show the efficiency of the proposed mechanisms and highlight their benefits and drawbacks.

Keywords: CAN bus,embedded system,fixed priority,resource management

Identifier: 10.3182/20071107-3-FR-3907.00018

Conference: 7th IFAC International Conference on Fieldbuses and Networks in Industrial and Embedded Systems (2007)

Location: Toulouse University, France

Start Date: Wed Nov 07 2007 - End Date: Fri Nov 09 2007

Authors: Peter Neumann; Axel Poschmann

Abstract: The aim of a Virtual Automation Network is to handle successfully the transfer of data through a heterogeneous communication network from the point of view of an automation application. Thus, the aim is to use the greatest amount of legacy LAN, WAN and industrial communications mechanisms. VAN does not describe a new communication protocol. However, from the point of view of an automation application, the specifics of a heterogeneous network have to be hidden. The paper describes the main characteristics, topology, and system architecture of a Virtual Automation Network (VAN).

Keywords: industrial communications,distributed control systems,heterogeneous networks,topology,system architecture

Identifier: 10.3182/20071107-3-FR-3907.00023

Conference: 7th IFAC International Conference on Fieldbuses and Networks in Industrial and Embedded Systems (2007)

Location: Toulouse University, France

Start Date: Wed Nov 07 2007 - End Date: Fri Nov 09 2007

Authors: Friederich Kupzog; Peter Palensky

Abstract: This paper focuses on wide-area control systems for that Internet-based communication, although being the only economically feasible option for communication, is insufficient for reliability or transmission delay reasons. An example for such a control system is the modern electricity system, which is currently changing from the traditional hierarchical to a more and more peer-to-peer oriented structure, and thus having growing demands for modern IT and control solutions. While up to now consumers were considered passive players, a new generation of automated demand response emerges, where consumers can react on real-time prices, on grid parameters like frequency or on transport schedules, in terms of their energy consumption. For enabling these features, a robust wide-area control infrastructure has to be developed, that allows for low delay transmission of control commands and measurement data. Further, it is critical to find simple and consistent models of the involved processes to design the respective control infrastructure according to its needs. This paper describes a novel approach for the design of distributed wide-area control systems that utilises process-specific parameters (here: grid frequency changes) as a new means of fast and reliable communication besides conventional communication channels.

Keywords: energy management systems,distributed control,decentralized control systems,algorithms,models

Identifier: 10.3182/20071107-3-FR-3907.00048

Conference: 7th IFAC International Conference on Fieldbuses and Networks in Industrial and Embedded Systems (2007)

Location: Toulouse University, France

Start Date: Wed Nov 07 2007 - End Date: Fri Nov 09 2007

Authors: J. Silvestre; V. Sempere; T. Albero

Abstract: Wireless Local area networks (wLANs), particularly from standards 802.1b/g, have become extremely widespread in a very short time, in society in general as well as at an industrial level. One of the limitations of this technology is its coverage. The family of new standards, such as 802.16, allows us to overcome these limitations, enabling then their use as Metropolitan Area Networks (MAN), as required by some application domains of industrial networks. In the present work we present an application of this technology in telemonitoring systems on metropolitan areas which shows their potential, but also the complexity of predicting their behaviour in a dynamic scenario such as a large city.

Keywords: wireless metropolitan area networks,telemonitoring

Identifier: 10.3182/20071107-3-FR-3907.00036

Conference: 7th IFAC International Conference on Fieldbuses and Networks in Industrial and Embedded Systems (2007)

Location: Toulouse University, France

Start Date: Wed Nov 07 2007 - End Date: Fri Nov 09 2007