Analysis of Switched Ethernet Networks with Different Topologies Used in Automation Systems
01 Jan 1999-pp 351-358
TL;DR: In this paper Switched Ethernet networks with different topologies are analyzed concerning the transmission delays and a typical master-slave scenario of an automation system is investigated.
Abstract: 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.
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TL;DR: This paper shows that vehicles using CSMA/CA can experience unacceptable channel access delays and, therefore, 802.11p does not support real-time communications, and presents a potential remedy for this problem, namely, the use of self-organizing time division multiple access (STDMA).
Abstract: Traffic safety applications using vehicle-to-vehicle (V2V) communication is an emerging and promising area within the intelligent transportation systems (ITS) sphere. Many of these new applications require real-time communication with high reliability, meaning that packets must be successfully delivered before a certain deadline. Applications with early deadlines are expected to require direct V2V communications, and the only standard currently supporting this is the upcoming IEEE 802.11p, included in the wireless access in vehicular environment (WAVE) stack. To meet a real-time deadline, timely and predictable access to the channel is paramount. However, the medium access method used in 802.11p, carrier sense multiple access with collision avoidance (CSMA/CA), does not guarantee channel access before a finite deadline. In this paper, we analyze the communication requirements introduced by traffic safety applications, namely, low delay, reliable, real-time communications. We show by simulation of a simple, but realistic, highway scenario, that vehicles using CSMA/CA can experience unacceptable channel access delays and, therefore, 802.11p does not support real-time communications. In addition, we present a potential remedy for this problem, namely, the use of self-organizing time division multiple access (STDMA). The real-time properties of STDMA are investigated by means of the same highway simulation scenario, with promising results.
264 citations
22 Sep 2004
TL;DR: In this paper, a bypass clock instead of the boundary clock is proposed as an enhancement of the IEEE-1588 standard for bridged networks, where the local clock adjustment can be modeled by a corresponding control loop.
Abstract: The IEEE-1588 standard for a high precision time synchronization now exists since 2002. For using this standard in bridged networks a so-called boundary clock is defined, where the local clock adjustment can be modeled by a corresponding control loop. At the field level of industrial automation systems, the line topology is very important. By using Ethernet at the field level, the resulting chain of bridges leads to a cascade of control loops and may lead to instabilities and deviations of the distributed clocks, which are not acceptable. For this application a bypass clock instead of the boundary clock is proposed as an enhancement of the IEEE-1588 standard. The effectiveness of this extension to be evaluated by simulation technique.
137 citations
Cites methods from "Analysis of Switched Ethernet Netwo..."
...The effectiveness of this extension will be evaluated by simulation technique....
[...]
01 Sep 2007
TL;DR: This paper focuses on line topology and is based on EtherCAT and PROFINET, which are two popular representatives of different architectures for high performance Industrial Ethernet networks.
Abstract: The evolution of industrial communication inexorably moves to Industrial Ethernet networks. One important reason for using Ethernet at the shop floor is to participate on the continuous advancements of standard Ethernet. Thus it seems to be the logical next step to change the bit rate from Fast Ethernet to Gigabit Ethernet to achieve better performance. The question is, how the cycle time as a relevant performance metrics of industrial automation systems can profit from increasing the bit rate to 1 Gbps. Because of its importance for the industrial automation domain this paper focuses on line topology. The analysis is based on EtherCAT and PROFINET, which are two popular representatives of different architectures for high performance Industrial Ethernet networks.
108 citations
Cites background from "Analysis of Switched Ethernet Netwo..."
...Thus it seems to be the logical next step to change the bit rate from Fast Ethernet to Gigabit Ethernet to achieve better performance....
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...Figure 14 shows the same scenario as in Figure 13 using Gigabit Ethernet....
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...By using Gigabit Ethernet the PHY delay was set to 250 ns, which is typical for modern gigabit PHYs....
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...Thus PROFINET becomes 50% faster than EtherCAT when using Gigabit Ethernet....
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BMW1
TL;DR: Simulation results of promising use cases for in-car Ethernet use cases are shown, while looking at different realistic topologies, types of traffic, and configurations.
Abstract: In current vehicles, a large number of control units are connected by several automotive specific communication buses, facilitating innovative distributed applications. At the same time, computers and entertainment devices use IP and commodity communications technology like Ethernet to connect to the Internet, allowing for innovative solutions and maintaining fast innovation cycles. Today, one can see first applications of Ethernet for in-vehicle communication in contemporary cars. In next generation vehicles, many innovative applications could benefit from the increased bandwidth Ethernet can offer. Therefore, a examination of Ethernet usage for additional in-vehicle communication use cases is needed. In this paper, we show simulation results of promising use cases for in-car Ethernet, while looking at different realistic topologies, types of traffic, and configurations.
100 citations
Cites methods from "Analysis of Switched Ethernet Netwo..."
...analyzed the cycle times and the latencies for automation systems in different topologies based on a switched Ethernet network: daisy chain, ring and tree [7]....
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19 Jun 2002
TL;DR: This paper proposes a hybrid wired/wireless PROFIBUS solution where most of the design options are made in order to guarantee the proper real-time behaviour of the overall network and addresses the timing unpredictability problems placed by the co-existence of heterogeneous transmission media in the same network.
Abstract: PROFIBUS is an international standard (IEC 61158) for factory-floor communications, with some hundreds of thousands of world-wide installations. However, it does not include any wireless capabilities. In this paper we propose a hybrid wired/wireless PROFIBUS solution where most of the design options are made in order to guarantee the proper real-time behaviour of the overall network. We address the timing unpredictability problems placed by the co-existence of heterogeneous transmission media in the same network. Moreover, we propose a novel solution to provide inter-cell mobility to PROFIBUS wireless nodes.
63 citations
References
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Book•
01 Jan 1993
164 citations
Book•
31 Dec 1993
TL;DR: This expanded and updated edition is the most comprehensive on the subject and covers new topics including switching hubs, routers and the Ethernet's role in multimedia networks.
Abstract: From the Publisher:
The new generation of Ethernet networks can perform as fast as ATM and cost about a quarter of the price. A prolific author of computer books provides a detailed introduction to LAN technology, describes the operation of each type of Ethernet network and discusses LAN performance. This expanded and updated edition is the most comprehensive on the subject and covers new topics including switching hubs, routers and the Ethernet's role in multimedia networks. Contains over 100 charts, tables, halftones and diagrams.
30 citations
Book•
01 Jun 1995
TL;DR: The purpose of Network Management applications, including Fast Ethernet Network Management Features, and changes to Previous Clauses, which have been published are described.
Abstract: Fast Ethernet. 1. Ethernet. How Ethernet Got Its Name. Early Development. Before Local Area Networks. The Ethernet Architecture. The Ethernet Control System. Commercial Development. Standards. Who Published the Ethernet Standard. How the IEEE Works with Other Standards Bodies. Where Fast Ethernet Fits in the Picture. Evolution. Thick Coax (Original Recipe). Cheapernet. StarLAN and Hierarchical Wiring. 10BASE-T Gets the Formula Right. Centralized Management. Bandwidth: the Need for More. Origin of Fast Ethernet. 2. Fast Ethernet. Overview. CSMA/CD. Basic Topology. Cables Supported. Use of External Transceiver. New Protocol Sublayers. Advanced Capabilities. Products. Adapter Architecture. Repeater Architecture (Shared Architecture). Switch Architecture. Application of Fast Ethernet. Implementing a Mixed 10/100 Mb/s Network. Implementing a Pure 100 Mb/s Network. Network Performance. Finding the Bottlenecks is Hard. Characterizing a Network. Characterizing Part of a Network. Real Network Performance. 3. Detailed Guide To Fast Ethernet. Changes to Previous Clauses. 100BASE-T Introduction (Clause 21). OSI Reference Model. Organization of T4 and X Clauses. Material Common to All Clauses. Media Independent Interface (Clause 22). MII: New Features. MII: Options. MII: Applications. MII: Management Features. 100BASE-T4 Transceiver (Clause 23). 100BASE-T4: Distinguishing Features. 100BASE-T4: Other Features. 100BASE-T4: Frame Structure and Encapsulation. 100BASE-T4: Options. 100BASE-T4: Features Not Needed. 100BASE-T4: Cables and Connectors. 100BASE-T4: Exceptions to ISO 11801 Wiring Practice. 100BASE-T4: Signal Levels, Comparison to 10BASE-T. 100BASE-T4: Safety. 100BASE-T4: Confusion with Telephone Wiring. 100BASE-T4: 120-ohm Wiring. 100BASE-X Transceiver (Clause 24). 100BASE-X: Relation to ANSI FDDI standards. 100BASE-X: Distinguishing Features. 100BASE-X: Other Features. 100BASE-X: Frame Structure and Encapsulation. 100BASE-X: Options. 100BASE-X: Features Not Needed. TX PMD (Clause 25). 100BASE-TX: Cables and Connectors. 100BASE-TX: Exceptions to ANSI TP-PMD. 100BASE-TX: Signal Levels, Comparison to 10BASE-T 100BASE-TX: Safety. 100BASE-TX: Confusion with Telephone Wiring. FX PMD (Clause 26). 100BASE-FX: Cables and Connectors. 100BASE-FX: Exceptions to ANSI Fiber PMD. 100BASE-FX: Signal Levels. 100BASE-FX: Distances. 100BASE- FX: Environmental specifications. 100BASE-FX: Use of Single-Mode Fiber. Repeaters (Clause 27). 100BASE-T Repeater: Distinguishing Features. 100BASE- T Repeater: Other Features. 100BASE-T Repeater: Options. Auto-Negotiation (Clause 28). Auto-Negotiation: Distinguishing Features Auto-Negotiation: Other Features. Auto-Negotiation: Options. Topology (Clause 29). Basic Model 1 Topologies (Single Collision Domain). Bit Budget Calculation Method (Single Collision Domain). Simplified Constraint System (Single Collision Domain). Management (Clause 30). Purpose of Network Management. Structure of Network Management Applications. Fast Ethernet Network Management Features. Protocols for Network Management. 4. Generic Cabling. Generic Wiring Architecture. Horizontal Cabling. Preferred Cable Combinations. Crossover Wiring. Answers to Commonly Asked Questions. Planning an Installation... About T4... About TX... About FX... 5. The Future of Fast Ethernet. Switching. Full Duplex Ethernet. Multimedia. Flow Control. Full duplex. Link level flow control. Bandwidth allocation. Binary Logarithmic Arbitration Method. Priority Access Control Enabled. Link Transmission Technology. ISO-Ethernet. Wide-Area Networking. 6. Comparison of Networks. FDDI. FDDI Overview. FDDI Strong Points. FDDI Weak Points. ATM. ATM Overview. ATM Strong Points. ATM Weak Points. DPAM. DPAM Overview. DPAM Strong Points. DPAM Weak Points. Fiber Channel. Fast Ethernet. Fast Ethernet Overview. Fast Ethernet Strong Points. Fast Ethernet Weak Points. 7. Collision Domains: Extra for Experts. What is a Collision Domain? How MAC Timing Works. Why the Diameter of a Collision Domain Matters. 8. Reference Materials. Books About Ethernet. Books About Other High-Speed LANs. General Books About LAN Technology. Ordering Ethernet Documents. Standards Closely Related to Fast Ethernet. Sources. Clauses of IEEE Std 802.3. Recent Supplements to IEEE Std 802.3.
24 citations