Distributed communication architecture

ork, managers can use them fully. Introduction Most factory floor networks are not ready to take manufacturing into the next millenium. The DCA product line from Hirschmann provides manufacturers with a practical high-performance answer with the ability to operate distributed high-bandwidth networks, delivering unmatched performance through sophisticated robust design Hirschmann DCA - a strategy for the next millennium The industry is dominated by legacy fieldbus solutions. So-called fast control networks generally operate at a meagre 1 or 2Mbps and lack the ability to scale to multi-megabit speeds and support thousands of devices. Newer fieldbuses like 12Mbps Profibus promise higher performance, but with an accompanying expensive price-tag. Foundation Fieldbus are now committed to using 100Mbps Fast Ethernet for the long awaited H2 specification. Of these alternatives, it is only Fieldbus Foundation with the H2 standard that has the potential to provide an optimal solution for Industrial automation networks. This is the market opportunity targeted by Hirschmann's Distributed Communication Architecture. Designed to meet the demands of the most mission-critical application, DCA is optimised to deliver the deterministic performance, scalability and high resilience required by these applications at price-points far below those of today's fieldbus solution. Hirschmann's Distributed Communication Architecture describes a control network strategy for the next millennium. Strategic direction Simply, Hirschmann's DCA network architecture defines the strategic direction for its next generation Ethernet fieldbus products - IndustrialLine. The combination of new demands on the factory floor network and the emergence of the intranet/Internet technologies has pushed current-generation fieldbus designs to their architectural limits. Although elegantly simple in concept, DCA is a radical rethinking of the control network architecture - and also defines the strategic direction for the development of the Hirschmann IndustrialLine products. The DCA architecture is the means by which Hirschmann will deliver high performance and guaranteed quality of service for real-time processes as well as easy, low-cost deployment, thanks to its compatibility with legacy fieldbus solutions. Why do you need a network architecture? Users are going to be spending large amounts of money on new automation and control networks to meet the forthcoming bandwidth and performance crisis, so it makes sense to do it right first time. A well thought-out network architecture outlines the solution to this crisis and gives customers confidence about a vendors capability to answer both current and future needs. Flexibility for the future As the automation and control infrastructure changes over time, the network architecture must incorporate the necessary flexibility to accommodate evolving user needs. Investing in the network today will buy flexibility for tomorrow. The lack of a single transparent automation and control network The past lack of an appropriate automation and control network architecture coupled with the lack of standardisation of vendor offerings has prevented the rapid development of new products and new vendor services. The subsequent lack of competitiveness (or dominance of any single vendor-driven set of "standards") and the complexity of current three-tier control networks has opened a new window of opportunity for vendors who want to embrace a new architecture. The diagram below shows how and when Ethernet is going to push down from the information level all the way to intelligent devices at the instrumentation level. The network is a long-term major asset For users, the deployment of an automation and control network and related equipment is a major expense and as a long-term major corporate asset and utility, a coherent network architecture justifies the spending of funds. Network architecture identifies the major components of a network and how they relate to one another. Since it is strategic in definition, individual components or devices may not be currently available, but available in a time-scale of about 18 months. In essence, it defines the ideal state of an actual implementation of a network. However, an architecture does not specify the exact sizing and placement of its components. Principles for industrial network architecture Although hardware and software implementation differs, the underlying standards for open, production management systems are the same as can be found in today’s business systems. That means freedom from the expense of maintaining specialized, one-of-a-kind systems to run their plants. Further, open systems unchain live manufacturing data, enabling companies to distribute it freely across enterprise networks in real-time to people who can use it to make a whole company run more effectively. Changing manufacturing practices are leading towards a new industrial automation and control infrastructure. As firms move into the global marketplace and implement advanced production processes, new technologies - such as Internet, wireless communications, graphical client/server applications, smart devices and decision support systems - are being deployed to reduce costs and streamline operations. However, these new tools and business processes create significant data distribution problems from the device level to the back office. Companies employing the latest automation and control techniques can expect a steep rise in bandwidth requirements, along with multiple challenges as they embrace technology to improve vendors' and customers' role in production. Emerging production processes, integrated systems and control/communications technology offer significant competitive advantages. For many years, the drive in manufacturing has been towards streamlined operations, improved response time to production schedule changes and the use of electronics to price and fill orders. Industry trends The Internet, and its associated technologies, has radically changed the way people go about their business today. It has improved communications throughout society and is now ubiquitous on a global scale. During the 1990’s the main user of the Internet has been people as they provide the intelligence to filter and sort the fast amounts of material available into useable information. This model is changing. In the world of office automation Internet technology has been designed into the devices that support the business and its infrastructure. Example of this evolutionary process can be seen in products as diverse as photocopiers and printers to LAN routers and voice PBXs. So why is this happening? The answer is simple - it makes sense! Giving intelligent devices the ability to communicate with the outside world is a good thing. In the case of the printer & copier automated ordering of consumables such as paper or toner, either to the office administrator or the supplier by email both saves time, money and increases availability of the device. As for the PBX, the ability for a device to inform the maintenance company when tolerances are exceeded and things start to go wrong, rather than wait for a complete system failure, saves time and money for all concerned. The additional benefit is that the technology differentiates the supplier through improved customer service & support. This value proposition, “to save time and money whilst offering increased service and support” has great worth in Industrial application where vast sums of money can be lost in a relatively short time when production or processes are halted. For the process and manufacturing industries, this is the year of change and a shift to new technologies. Underpinning all technological trends is the move towards open, transparent commercial installations based on intranet/Internet and away from legacy, vendor driven systems. Every part of the process control and automation industry - from embedded systems to the Fieldbus Foundation - has recognised the importance of Ethernet and TCP/IP. Ethernet has become the dominant network technology at the controller supervisory level. Every Controller, PLC and DCS vendor has an Ethernet interface and it is now moving downwards towards device and the I/O level. The need for high performance Industrial networks Adding these new processes, systems and technologies to today's automation and control communication infrastructure will stress it unbearably. Bottlenecks caused by, typically three, discrete networks (Plant, Control & Device) will need to be removed before networks become a transparent and plant wide utility. Over the past five years there have been many enhancements to the Ethernet standards, especially in areas of determinism, speed and prioritisation. There is no longer any reason why Ethernet cannot be used to build deterministic fieldbus solutions that are cost-effective and open. Since Ethernet is already the network choice for business computing, its presence at the control level will make sensor to boardroom integration a reality rather than a goal for manufacturers. With the physical bottlenecks removed raw transmission speed needs to be increased and management policies implemented to allow the various traffic types to be prioritised according to needs. The initial impact of adding new, bandwidth hungry applications will be on factory floor network, followed by WANs, should a manufacturer want to make key manufacturing data available to customers and other partners in its supply chain. Distributing manufacturing data is also a bandwidth intensive proposition. Over the next four years, manufacturing plant information generated by DCS equipment is expected to increase by 20 or 30 times the current level. Similarly, a 10 or 20 times increase is expected in PLC equipment collecting information from the factory floor. Distributed control systems (DCS), Controllers and programmable logic controllers (PLCs) also eat up bandwidth. These enabling technologies facilitate smart sensors and devices on the factory floor. Smart sensors mounted on process equipment are now capable of network connectivity throughout the factory; and each sensor being individually addressable and intelligent. Distributed Communication Architecture – DCA The Hirschmann Distributed Communication Architecture provides suppliers and end users with: a statement of direction for industrial networks a blueprint for future industrial network growth A statement of direction for industrial networks To meet the demands of the next generation of automation and control system, the network will require a new architecture comprising six key dimensions: real time, migration from legacy systems, resilience, management, performance and cost. Real time Whether you are designing a small, medium or large control network, Hirschmann networks are designed to grow as end user needs grow and to meet the needs of higher bandwidth real-time applications smoothly. With Hirschmann's Distributed Communication Architecture, its policy-based QoS makes sure high-priority traffic for certain messages always gets through. Migration Hirschmann integrates legacy devices, instrumentation and I/O through gateways supporting existing control and device networks. These gateways also aid smooth migration of installed control networks to Ethernet. Topology & Resilience Ethernet and TCP/IP based networks are inherently scalable by design. The Internet, with its millions of end stations is testament to this. On a local level, single mode fibre optics can move data at rates of 10, 100 or 1000Mbps over distances exceeding 20km with a single hop. Multiple hops and differing topologies (bus, star or ring) extend this even further. Created from the start as mission-critical products, Hirschmann's IndustrialLine offers no single point of failure in a network, either physically or logically Management Hirschmann's Distributed Communication Architecture (DCA) offers comprehensive management capabilities via Web browser, SNMP and priority-based VLANs. Performance Because of DCA's scalability, Hirschmann can give all level of the control and automation network the bandwidth it needs at the level of the network which makes most sense. Ethernet transmission speeds from 10Mbps to 1000Mbps are all fully standardised. Cost. Today, nothing can compare with Ethernet as the lowest cost implementation for a control network. The ability to take advantage of the existing support infrastructure for Ethernet is a major benefit to suppliers and dramatically reduces the total cost of ownership. Cost is also a factor from a development perspective, TCP/IP communications software and the underlying ASIC chips are commodity, mass market items and priced accordingly. A blueprint for future industrial network growth Greater openness/interoperability with other devices, management software and control platforms. Hirschmann DCA provides an open communication architecture compared to legacy control networking and connectivity. Vendors want openness to reduce client software expense and increase access to devices and other products. Reduced dependence on costly, highly skilled field installation and support functions - through automatic Internet Web connection and services. Greater partnership with end users offering open independent solutions with superior support services. Section 2 An industrial networking architecture for the next millennium The demand for ‘open’ industrial communication systems is being driven by end users' desire to move away from older, centralised plant control strategies to distributed control in the field. End users want an enabling technology that provides true device inter-operability, enhanced field-level control, simplified maintenance and reduced installation costs. The only network architecture capable of delivering against these requirements will offer deterministic high performance, be standards based and non-vendor specific. The future of automation New approaches to process and manufacturing automation, which will have a tremendous impact on the design of control networks, include: Manufacturing execution systems (MES). Computer-based information and command for managing production resources, processes, costs, labour, data collection, documentation, and work-in-progress, etc. Data collection. New technologies for traditional functions such as time and attendance recording, labour reporting, and materials tracking. Computerised maintenance management systems (CMMS). Graphical views of process equipment and processes accessed by multiple users to pinpoint faults and failures, order design fixes and accelerate repairs and changes. CCTV for monitoring Data warehouses. Quality information systems. For tracking compliance with ISO9000 and industry-specific benchmarks. Decision support systems. Product data management. Electronic forms. Data support for control and automation processes. These new applications will demand higher bandwidth than ever before from plant, control and fieldbus networks. This increased bandwidth is simply not available from low speed fieldbus systems. The Vision Most plant data collection applications use a batch approach, where data is transmitted at the end of the shift or other low usage times of day. New networking technologies will change this model to real-time, with plant information being continually and automatically collected and analysed - without operator intervention. Plant operations will increasingly be directly connected in a client/server model to host computers and servers. Controllers, PLCs and Enterprise Resource Planning (ERP) systems will be able to access any sensor connected to the control and device network. The result will be better information on manufacturing processes. Imagine the impact of every shopfloor worker having the equivalent of a handheld, possibly wireless network browser at his or her disposal. In real time, process operators will be able to monitor and fine tune system performance, access plant information and communicate directly with their production line managers. These operational online continuous nodes will be another bandwidth consumer, raising traffic levels significantly. And the network will not only supply information internally. Trends towards quick-response, vendor-managed inventory and electronic commerce, are demanding that manufacturing at the centre of the supply chain be brought online. Customers and suppliers need to be able to look at all points in the supply chain, from initial order placement to raw material consumption to assembly to shipment and delivery. Decision support systems and data warehousing applications will soon be able to "mine" massive amounts of data for correlation and trends that can lead to operational improvements. With manufacturing equipment and personnel on the network, higher management can have access to the operational data on the factory floor in unprecedented detail. The new factory floor network will also affect network capacity planning in the same way as switched networks impacted on traditional shared LAN designs. In future, IT/network managers will also need to be aware of developments on the factory floor generating additional traffic which will impact office LANs and servers and, eventually, WAN traffic. Another way of looking at this is of office users extending their reach towards the factory floor. Table 1 shows how key business line functions correspond to plant information sharing and data communication requirements. Table 1 Function Information sharing / Data requirements Operations Detail scheduling Sequencing, priorities, routings, shape, fit, setup, alternative / overlapping / parallel operations, equipment loading, shift patterns Dispatching Production units Flow, jobs, orders, batches, lots,work orders, sequences, changes,events, schedules, controls, buffers Process management Monitor, control, correct, decision support, tracking, alarms, tolerances Product tracking and genealogy Visibility, status, who is working on what components, suppliers, lots, serial numbers, environments, alarms, rework steps, exceptions, history, tracing, usage Performance analysis Up-to-the-minute status, results, history, measurements, utilisation, availability, cycle time, conformance to schedule, performance to standards, parameters, reports Quality management Analysis, measurement, collecting, quality control, identifying problems, correlation, symptoms, actions, results, tracking, inspection Document control Forms, instructions, recipes, drawings, standard procedures, programs, batch records, EC notices, as planned" and "as built" Data collection/ acquisition Interfaces, links, production/parametric data, forms, scanned transaction records, other collected data. Complimentary technologies that support such network related business functions are many and varied. They include: smart sensors and fieldbus devices. Electrical panels and intelligent circuitry in specialised local factory networks which enable multiple performance measurements on production line equipment, operations and materials. high bandwidth devices. Ethernet interfaces, data collection terminals, radiofrequency (RF) devices/transmitters and programmable controllers. traceability. RF tags, barcodes and smart cards. client/server installations & thin clients Internet access As these technologies mature over the next couple of years, current bandwidth levels are expected to hit their ceilings and new network solutions will be required. For control systems, the immediate focus is the factory floor network. Today, many devices are connected to a control network through proprietary serial cabling and protocols. Information is then consolidated from the control network running at speeds typically under 2Mbps. For this information to reach the corporate systems it must cross the divide between the control network and the information network with its links back into the enterprise office automation (OA) network. Typically this function is carried out by a PC based gateway or HMI workstation. With interfaces to the proprietary control network on the one side and the Ethernet/TCP/IP based information network on the other, the gateway provides a route, albeit restricted, across the divide. In the majority of cases today, the information network utilises 10Mbps shared Ethernet. The first casualty of the information explosion will be the legacy fieldbus system with 2Mbps as its upper limit. Shared 10Mbps Ethernet will also be replaced initially by 10Mbps switched increasing to 100Mbps as need dictates. Ethernet will also extend its reach, driving the technology closer to intelligent devices and remote I/O. The Internet and modern networking designs will enable four major functions to be radically improved. Easier product installation for remote or local personnel using HTTP server and browser technology set up, re-configuration and status monitoring Diagnostics/repair help find and solve problems with device or devices' mission using SNMP, FTP, peer-to-peer or HTTP technology and memory dumps to host for analysis, download programs to RAM or flash memory Use the HTTP server to gather a wealth of information from a device Management reporting and network capacity planning Criteria for network evaluation REAL-TIME Ethernet Legacy Fieldbus Application target ALL ALL Determinism YES YES Response time 4ms or less 5ms or less Message size ALL SIZES LIMITED MIGRATION Ethernet Legacy Fieldbus Geography WORLD-WIDE REGIONAL Backwards compatibility HIGH LOW Degree of openness HIGH LOW Interoperability HIGH LOW Standardisation IEEE 802.3 EN 50170 / Fieldbus Foundation Network Security HIGH HIGH Protocol TCP/IP PROPRIETARY TOPOLOGY & RESILIENCE Ethernet Legacy Fieldbus Automation level Business YES NO Control YES YES Device YES YES Bit-sensor GATEWAY YES Physical Connectivity Media TP, FIBER, COAX, AUI, WIRELESS COPPER, FIBER Devices connected CONTROLLERS, FIELD DEVICES, REMOTE I/O CONTROLLERS, FIELD DEVICES, REMOTE I/O Max no of nodes 64000 500 Nodes per segment 1-256 (APPLICATION DEPENDANT) 48 Distance between nodes Up to 40Km Up to 20Km Continued… Ethernet Legacy Fieldbus Repeaters for longer distances YES YES Logical Connectivity Communication modes VARIED VARIED Internet/intranet YES NO Resilience Reliability HIGH HIGH Scalability HIGH MEDIUM Redundancy YES YES Hot insertion of devices YES SOME MANAGEMENT Ethernet Legacy Fieldbus Plug'n'play support YES NO Network topology BUS, STAR, RING BUS, STAR,RING VLANs YES NO HTTP / WWW YES NO SNMP YES NO ISO Levels supported 1, 2, 3, 4, 5, 6, 7 1, 2, 7, User Layer PERFORMANCE Ethernet Legacy Fieldbus Data transfer rate HIGH LOW Speed 10 / 100 / 1000 Mbps 1-12 Mbps Scalability HIGH MEDIUM COST Ethernet Legacy Fieldbus Cost LOW HIGH Cost per connection LOW HIGH Cost of Ownership LOW HIGH Sourcing MULTIPLE SINGLE VENDOR Section 3 The Ethernet Evolution Advances in commercial networking technology have been coming so fast that it has grown difficult for automation and controls suppliers to keep comparable elements of their legacy systems abreast with state-of-the-art network developments. With the networking industry offering dramatically increased bandwidth, commercially available Ethernet equipment is now beyond what suppliers can hope to develop in-house in terms of fieldbus and control networks. For vendors, in-house development of computer hardware, operating systems and networking elements, which can be purchased cost-effectively on the open market, exacts a fierce toll. It is very expensive for suppliers to support 20 year old, proprietary systems. Originally ignored by the Automation industry because of its perceived lack of determinism and robustness, Ethernet has evolved into a technology which the automation and control industry is swiftly adopting. Ethernet TCP/IP is a widespread network technology, with users exceeding 100 million world-wide. Ethernet PC boards sell for sub $30 compared to the $900 or more for a control or device network PC board. In addition, the growing acceptance of Microsoft Windows NT and its incorporation of Ethernet drivers into the operating system enhance Ethernet as the backbone of high-speed control and device networks. Further, Windows CE is being considered as an embedded operating system for devices and controllers, leveraging Windows NT capabilities. Many PCs include an Ethernet network interface card at little or no cost. Ethernet TCP/IP also offers easy connection to the Internet, which is gradually filtering its way into the world of industrial automation and control systems. Devices sitting on an Ethernet TCP/IP network need only be assigned an IP address for Internet connectivity. In addition, a complimentary Internet technology – Java, is already being used in applications from automation and control suppliers. To meet the demands of industrial control networks, Ethernet architecture must be based on six main criteria: real-time capabilities, migration, topology & resilience, management, performance and cost. A brief history The history of local area networking is relatively short - Ethernet was the first working LAN. It was developed at the Xerox Palo Alto Research Park, beginning in 1973, by a team headed by Dr Robert Metcalfe. Ethernet was first widely employed commercially to network terminals to minicomputer systems - more specifically, to network Digital Equipment Corp terminals to its VAX line of minis. Unix-based workstations and scientific workstations were also connected by Ethernet early on. The original published specifications were known as DIX (Digital, Intel, Xerox) Ethernet Specifications Versions 1.0 and 2.0. The IEEE adopted, improved and modified the DIX Version 2.0 specification. This became the IEEE 802.3 standard, which is equivalent to the ISO 8802/3 standard. The first IEEE Ethernet standard was published in 1983, defining what we know today as 10Base5 or thick Ethernet. The earliest commercial network, Ethernet, used a bus - a single data path to which all workstations attach and on which all transmissions are available to every workstation. Only the workstation to which the transmission is addressed can actually read it, however. A bus cable must be terminated at both ends to present a specified impedance to the network workstations. The road to deterministic Ethernet How can only one computer at a time be allowed to transmit on the network? Access to the network - the right to transmit - can be allocated in one of two ways: randomly or in a deterministic order. In a random access method, any station can initiate a transmission at any time - unless another station is already transmitting. In a deterministic access method, each station must wait its turn to transmit. Carrier-Sense Multiple Access / Collision Detect (CSMA/CD) is the random access method used for bus arbitration within the original shared Ethernet standard of IEEE802.3. CSMA/CD and random access are best suited where network traffic is unpredictable and bursty, consisting of many short transmissions. Since industrial networks are characterised by their deterministic nature, consistent low latencies and low jitter, it is hardly surprising that the leading Automation vendors regarded early Ethernet as unsuitable and developed their own networking solutions. However, rapid developments in Ethernet switching technology in the early 1990s’ have eliminated what were once barriers to the adoption of Ethernet as the control network of choice. With its speed, robust performance, low cost of deployment and constantly updated technology, Ethernet is a natural fit into the automation and control hierarchy. Ethernet is typically used in manufacturing operations for communication both between business system components and plant networks. Ethernet's capability to easily communicate with multiple devices and manage the traffic to the information level of the plant make it an ideal candidate for use at the control & device level. Ethernet developments over the past decade A new version of Ethernet, 10BaseT, appeared in the late 1980s. It uses twisted pair (TP) wiring and is arranged in a star topology. Yet the network acts as a logical bus. That is to say, signals transmitted by any workstation are available on the network to all workstations. Only the station for which the transmission is destined can read it. Ethernet switching arrived on the scene during 1992. The best analogy to switched Ethernet is switched voice and the PBX voice switch. Ethernet switches also support multiple simultaneous communications between many devices without collisions. Using addressing information contained in each Ethernet frame a switch forwards data to a switch port to where the destination equipment can be reached. The ability to switch an Ethernet frame to a specific destination based upon information in the Ethernet frame rather than broadcast the frame everywhere was the first step in making Ethernet deterministic. Ethernet switching has since revolutionised the business of networking, originally demanding a premium switched ports are now priced at a level where it makes good sense to deploy them widely. IEEE 802.3x brought with it standardised full-duplex operation and link based flow control. Full duplex working in point-to-point mode, further overcame the issue of determinism by giving a single station full wire rate connection, with no risk of data collisions. It is collisions caused by two devices attempting to transmit at the same instant that made Ethernet unpredictable when loaded. Where contention is a network issue, flow control provides a means whereby an Ethernet switch can indicate to transmitting stations that congestion exists in the network and that they should pause transmission. The next evolution was Fast Ethernet (IEEE 802.3u), which is nearly identical to 10Mbps Ethernet. The packet length, packet format, error control and management information are identical to 10BaseT, but the speed is increased by a factor of 10. It is implemented as a star topology. IEEE 802.3ac, supporting the work carried out by the 802.1 p & Q IEEE working groups, added frame tagging for priority (8 levels) and VLAN identification which, when combined with Ethernet switching, delivers deterministic performance. Recently, Gigabit Ethernet (IEEE 802.3z) has been ratified, combining Fibre Channel technology with Ethernet media access, running at 1000Mbps (1Gbps) over fibre optic cabling. Hirschmann has specifically addressed current concerns about Ethernet's lack of determinism and redundancy using the standards described above and adding further, complimentary features that are specific to building industrial networks. The result is that Ethernet can now be adopted as the control & device network of choice. Several control suppliers have begun to move towards open systems by taking advantage of new technologies and incorporating them into their control systems. For example, Fisher Rosemount's DeltaV system uses standard Ethernet as the control network between workstations and controllers. Foxboro and Schneider Automation use Ethernet products as the backbone of their control networks. Evolving standards Three phases in the evolution of the Ethernet fieldbus can be identified. In the first phase, Ethernet replaces proprietary fieldbus connectivity and wiring as well as proprietary fieldbus signaling implementations. Above Layer 1, all fieldbus protocols are specific to the control network supplier. There are many examples of this type of implementation such as Foxboro's Micro I/A Series which uses Ethernet for connectivity between workstations and controllers, but retains a proprietary protocol to communicate between controllers. Phase 2 Phase 3 Phase 1 In the second phase, Layers 1 through 4 proprietary fieldbus protocols are replaced with open networking protocols i.e. Ethernet TCP/IP. However, higher layers retain their proprietary nature in order for suppliers to maintain differentiation. Examples of this approach include Modbus which is underpinned with Ethernet TCP/IP but has added application software in order to support the requirements of its field devices. In the third phase, the trend towards a "standard fieldbus" becomes inevitable, driven by user demand. The key example is the recent conversion of the Fieldbus Foundation for its H2 fieldbus architecture to be based on Fast Ethernet. "The Foundation's Fast Ethernet program is a direct response to the expressed needs and requirements of end users," said Fieldbus Foundation President, John Pittman. Section 4 A time for change End users want an enabling technology that provides true device interoperability, enhanced field-level control and reduced installation costs. However, both suppliers of controls and instrumentation and end users continue to seek a single international fieldbus standard. Suppliers want to base their new product developments on an open, non-proprietary fieldbus protocol that is available to any company that wishes to implement it. Market dynamics Every part of the process control and automation industry - from embedded systems to the Fieldbus Foundation - has recognised the importance of Ethernet and TCP/IP. Ethernet has become the dominant network technology at the controller supervisory level. Every PLC and DCS vendor has an Ethernet interface and it is now moving downwards towards the I/O and device level. For example, NETsilicon (fomerly Osicom) is pricing its embedded Ethernet TCP/IP chips at commodity prices that will open the door to Ethernet at the device and instrumentation level. In order to encourage take-up further, NETsilicon make starter kits available. Microsoft has committed to extend the real-time capabilities of Windows CE, its embedded operating system, with the twin goals of thread response latencies of 50 microsec or better and increasing the number of priority levels beyond its current eight. Windows NT is suitable for 80% of manufacturing and process control applications, Windows CE's proposed realtime capabilities will allow it to address 16% of the remainder, leaving a mere 4% for specialist embedded solutions. At the fieldbus level, the Fieldbus Foundation are incorporating open commercial high-speed Fast Ethernet into its H2 program as a direct response to user needs. Fisher-Rosemount uses standard Ethernet as the control network between its workstations and controllers in its DeltaV system. Foxboro was the first to adopt Ethernet as the backbone of its control system with its I/A Series. Initially, Foxboro modified the protocols to optimise Ethernet as a control bus, but today uses standard Ethernet. Similarly, Schneider Automation and GE Fanuc use Ethernet to network their PLCs. The industrial PC has also evolved in recent years from a mere graphics and data input terminal to a high-end operator interface with advanced control capabilities. This evolution has expanded its role from a simple interface to a programmable logic controller (PLC) into a dedicated PLC solution. While the traditional PLC cannot handle large volumes of data, the PC-based PLC integrates control and the logical functions of a PLC in software and runs these on a commercial operating system, such as Windows NT. In essence, it provides the functionality of the traditional PLC, but with the advantages of the PC environment including open Ethernet networking and free TCP/IP communications software and lower capital outlay. Internet and intranet access to real-time process information can be accessed using Java-enabled, Web application servers and standard browsers over TCP/IP and Ethernet. Using such Java tools, companies can unite control and computing equipment into a single, virtual network that overrides their incompatibilities. Java is the computing environment from Sun Microsystems that enables software to operate independently over an intranet or the Internet, ignoring differences in computer platforms that use the software. Vendor opportunities Since Ethernet is already the network choice for business computing, its presence at the control level will make the visionaries goal of sensor to boardroom integration a much easier task for manufacturers. The speed and data transfer rate of Ethernet comfortably exceeds those of high speed fieldbus, such as Profibus and ControlNet. Profibus has a maximum transfer rate of 12Mbps, while ControlNet is only 5Mbps. Standard Ethernet has a transfer rate of 10Mbps, with 100Mbps Fast Ethernet rapidly replacing it. With Gigabit Ethernet, the prospects of a 1000Mbps control network backbone become a reality. To address redundancy, the IEEE 802.1d standard provides the ability to add redundant links into a network to aid automatic recovery of network connectivity when there is a link or repeater failure anywhere in the network path. For control networks, however,the time to recover from a path failure is critical - and Hirschmann's Industrial Line recovers from failure several levels of magnitude faster than standard spanning tree implementations. In addition, IEEE 802.1p standard for message prioritisation aids control applications where timing of control information is critical and enhances the deterministic nature of Hirschmann Ethernet based control network solutions. In its Industrial Line, Hirschmann brings to Ethernet levels of determinism and resilience comparable to that found in today's fieldbus. However, Ethernet TCP/IP does not define the user layer specified in the Foundation Fieldbus, and also does not include function blocks and other features unique to fieldbus. For this reason, Hirschmann regards partnership with automation and control suppliers is key to delivering the proven benefits of Ethernet combined with the rich heritage of existing control network architectures. Any technology based company that isn't at least thinking about how to use the Internet and Ethernet is missing out on the next major wave of product opportunities. By the end of the next five years all products having anything to do with measurement, control and information gathering will be networked. Not only networked by Ethernet but also linked to Inter/Intranet/Extranet and Web enabled. The momentum behind Ethernet is unstoppable and its domination of the control and automation industry is certain. Nothing can surpass Ethernet as the lowest cost implementation of a transparent control network. Hirschmann's DCA provides the means to deliver a future-proof open Ethernet fieldbus family with all the resilience, reliability and deterministic benefits which in the past have only been found in proprietary legacy fieldbus solutions. The freedom vendors’ gain from open networking does not mean fewer opportunities. It means vendors will be able to add a lot more value by applying their expertise to providing reliable, fault-tolerant, real-time control packaged as co-ordinated transparent systems. Section 5 Hirschmann’s DCA The Distributed Communication Architecture (DCA) describes a robust standards-based Ethernet solution for all levels of the industrial automation and control environment, managing and handling information from instruments and sensors to control devices that intercommunicate with plant computer equipment. A blueprint for future industrial growth Manufacturing operations have to cope with unique problems - hazardous machinery, noisy environments, dirt and grease. Yet the challenges on the factory floor are similar to those faced in office networks when it comes to protocols, speed and throughput. Since Ethernet is already the network of choice for business level computing, its presence at the control will make sensor to boardroom integration a much easier task for control and automation suppliers. Vendors are always looking for ways to become more competitive. They are increasingly sales, service, and support-oriented. However, they need to find additional ways to increase revenues and decrease costs. Open networking - TCP/IP, Ethernet and Internet - provides new vehicles to meet these needs. Manufacturers are "the fountain of funds" and the last stop in the margin food chain. All other parts of the distribution cycle look to manufacturers to provide their margins. Margin enhancing strategies that are made possible by networking are new areas of leverage. These strategies have great potential and will be quickly adopted by suppliers' as soon as they understand the benefits. The Internet and Ethernet offer an almost limitless scope of new sales and margin increasing potentials. DCA permits supplier system engineers to develop networks better, faster, and at a lower cost. The Hirschmann Ethernet Fieldbus Approach Hirschmann's Distributed Communication Architecture has been developed to meet industry needs for: Greater openness/interoperability with other devices, management software and control computers. Hirschmann DCA provides an open communication architecture compared to legacy control networking and connectivity. Vendors want openness to reduce client software expense and increase access to device/products. Reduced dependence on costly, highly skilled field installation and support functions - through automatic Internet Web connection and services. Greater partnership with end users to strengthen dependence on the vendor while increasing the competitive barriers to entry. By lowering end user costs of vendor’s products based on standard networking technologies, and, using new applications enabled by them. For example: Ethernet cabling versus special purpose serial cabling, installation and commissioning. Automatic online preventative diagnostics More efficient maintenance and support using Web-based tools Easier to install and support Automatic updates of new technology and releases automatically increasing productivity usage of products Increased vendor revenue through Internet services Service/support contracts - delivered through the Internet Increased product firmware and software upgrade sales automatically delivered through Internet Ability to learn more configuration details - through registrations and suggest upgrades and new equipment justifications To meet these demands, the next generation of automation and control networks requires a new architecture that must have six key dimensions: real-time, migration from legacy systems, topology & resilience, management, performance and cost. Real-time Whether you are designing a small, medium or large control network, Hirschmann networks are designed to grow as end user needs grow and to meet the needs of higher bandwidth real-time applications smoothly. Wire-speed switching and VLAN support enables the network to scale to several thousand devices. Policy-based quality of service goes beyond simple bandwidth reservation to include bandwidth management, prioritisation and congestion control. Higher network loads and delay-sensitive messages from applications require sophisticated quality of service features. With Hirschmann's Distributed Communication Architecture, its policy-based QoS makes sure high-priority traffic for certain messages always gets through. An intelligently utilised Ethernet network out performs any control network for sending control messages between controllers. Even when carrying significant background traffic, Ethernet yields faster and more consistent message delivery times. Migration. While Ethernet can solve many application requirements, Hirschmann recognises that some may be better served using solutions targeted at specific applications. Hirschmann integrates these network application areas through gateways supporting existing device networks. These gateways also aid smooth migration of existing control networks to Ethernet. Topology & Resilience. Ethernet is fundamentally a bus architecture. The bus can be used by a single device connected to a switched Ethernet port in traditional half duplex mode or, for deterministic performance, ‘full duplex’ mode. Alternatively many users can connect to a single wire and share access to the Ethernet, using either: A ‘half duplex’ bus topology such as 10Base2 (Thinnet) or 10base5 (Thick Ethernet). Or A ‘half duplex’ star topology using 10BaseT (Twisted Pair) or 10BaseFL (Fibre) Created from the start as mission-critical products, Hirschmann's IndustrialLine switches benefit from no single point of network failure, either physically or logically, when configured in ‘single ring’ topology. Incorporating high levels of resilience as standard, the switches create an inherently "bulletproof" Ethernet network. Depending on how important the application is, the level of resilience in the overall network can be matched to meet further continuity requirements. For example, where a controller has dual redundant network interface cards each card could connect to separate switches on the same resilient fibre ring. or, if double redundancy is needed, a second ring could be added (as shown in the diagram below). Management. Hirschmann's Distributed Communication Architecture (DCA) offers comprehensive management capabilities via Web browser and SNMP. One weakness of Ethernet that DCA is that its openness means that potentially someone can gain access to the business level network through tapping into the control and automation network. The inherent security of VLANs means traffic can be restricted and the use of policies gives stringent levels of security. This enables different operators to use the system 24 hours a day, 7 days a week, without compromising mission-critical operations. In addition, secure access to control rooms and highly restricted remote access can be defined through policies. Performance Hirschmann switches extend Ethernet's evolutionary migration from 10Mbps to 100Mbps to 1000Mbps. This scalability is critical to LAN design and migration, enabling the plant manager to optimise the network by providing high-speed links for backbone and controller connections while maintaining performance at the device level. Hirschmann switches provide non-blocking switched links to every port, simultaneously. Switches must provide enough bandwidth within the network fabric to minimize the chance of network congestion. The switch must be capable of switching multiples of high- and low-speed ports simultaneously without blocking throughput on any port. Because of DCA's scalability, Hirschmann can give all levels of the control and automation network the bandwidth it needs at the level of the network that makes most sense. Cost. Today, nothing can compare with Ethernet as the lowest cost implementation for a control network. For example, a standard PC Ethernet card can be purchased for under $50. Compare that to buying a PC network card from control suppliers for any of the existing networks at between $500 and $1500, then the cost-effectiveness of Ethernet is obvious. The same commercial price pressure also applies to Ethernet hubs, switches and routers, where price erosion is the norm not the exception. This also does not take into account any special cabling, training and tools required for a non-Ethernet network. The ability to take advantage of the existing support infrastructure for Ethernet is a major benefit to suppliers and dramatically reduces the total cost of ownership. Since Ethernet is already the network of choice for business level computing, its presence at the control will make sensor to boardroom integration a much easier task for control and automation suppliers. Benefits Hirschmann Industrial Line is the complete networking system combining all the networking hardware and management software in a scalable product family, giving you these benefits: Hirschmann believes that the use of DCA will enable automation and control companies to bring open fieldbus networks, centred on Ethernet and TCP/IP, to market in the shortest time frame. Hirschmann with 10 years experience in industrial networking are the only networking company with a core competence in both Ethernet and industrial applications. What Hirschmann offers The IndustrialLine product family goal is to provide a broad range of connectivity solutions that are software compatible and cost effective. The DCA framework will span connection topologies, performance ranges and cost targets. The overriding goal will be to provide our supplier partners with a scalable range of connectivity hardware - complete products when they need them - while protecting their existing investments in technology. A key point for vendors is that even the most deterministic of control networks have limits on how many devices or nodes can be connected simultaneously in order to preserve deterministic performance. The same applies to Hirschmann Industrial Line. Although the Industrial Line has a high level of inherent determinism, Hirschmann will work alongside suppliers and tailor its products to meet individual requirements. Summary Most current control and automation networks cannot meet the data-intensive demands of the process industry into the next millennium. IndustrialLine products from Hirschmann provide suppliers with a practical high-performance network solution, with the ability to operate distributed high-bandwidth networks, delivering unmatched performance, determinism and resilience through sophisticated robust design. For product information from Hirschmann Network Systems, contact your local office.