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IAS is more than just a tag serverWonderware's industrial application server product enhances yag servers with a range of production services To manufacturing users, the new Industrial Application Server (IAS) from Wonderware looks and acts a lot like a tag server, but it's more than that. IAS provides a whole new tier of real-time data acquisition, alarm and event management, data manipulation services and collaborative engineering capabilities that have been designed from the ground up for use in industrial environments. It has been built upon Invensys' new ArchestrA platform and offers a new class of application server for both manufacturing and process industries. But why use servers at all? A decade ago development of typical automation software applications was relatively simple in concept. Programmable logic controllers (PLCs) ran equipment or process loops. Plant floor sensors, actuators and recording devices were connected to the PLC. Human-machine interface (HMI) software provided the PC-based visualisation needed to interact with the process under control. The problem was that as engineers built more functionality and sophistication into their applications, they were adding more data tags, a lot more scripting and many more alarms. In addition, as systems were scaled up to expand or enhance production lines it meant they had to add more PCs, PLCs and control devices. This in turn meant networks needed to grow as well and so that throughput wouldn't affected they were often segmented. While system engineers borrowed heavily from the client/server technology deployed in the business world, they could not use it efficiently because of the difference between business and industrial environments. They were able to offload tags and scripts to a common server, which reduced network traffic and client duplication. They used communications servers to offload data traffic management. Calculation engines were added to process data for use elsewhere within a running process. But each of these used a separate server implementation and typically servers were dedicated to a single application task. For example, a tag server would be used to acquire data from specified plant floor devices in an industrial automation application, then scale the data, check it for alarms and events that had occurred, and distribute the processed data to any user requesting it. This is how plant floor operators are notified when an alarm or an event occurs that needs their attention and intervention, as an example. Tag servers form part of a complete application system and are mainly responsible for offloading the data handling and manipulation functions between the human-machine interface (HMI) layer and the control device layer in the application. Their primary purpose is to maintain regular 'snapshots' of the state of the process under control. In large applications, users may use multiple tag servers to handle tags for specific groups of devices. This presents yet another configuration problem since each tag server must be programmed and addressed differently as a separate element of the application. Growing problemsWhile all of these approaches helped solve immediate problems, they only made an overall system harder to manage. As applications grew bigger and more complex, new problems were created administering networks, managing changes and scaling applications to add new lines. Enhancements to improve functionality or efficiency become harder to implement and change management has become an increasingly large cost element in re-engineering. The only realistic solution today is to borrow a page from the business IT world and move towards application servers but it will take more than just standard application server technology to meet the needs of the industrial world. In its typical historical development pattern, the industrial world has lagged the enterprise world by several years in its adoption of IT technologies and their adaptation to the factory floor. This has meant that application servers were most often used for business systems running software and databases information for use in customer resource management, e-business, financials and other enterprise applications. Most application servers provide services in a transaction-based environment, however, and that doesn't work in an event-driven industrial environment because the ground rules are different in a factory to those in an office. An industrial application server performs the same basic logic functions as its business counterparts, which is, providing services and data to multiple applications - but it must do so while fulfilling unique requirements of the industrial world. For examples:
The new Industrial Application Server from Wonderware provides all of this capability and more, all in one product. The company has created a server that complements existing factory software, providing an array of services that are usable by all industrial automation applications. This includes services such as: licensing, security, internationalisation (without multiple dictionaries), configuration, deployment, events, messaging, scripting, alarming, peer-to-peer services, and integration of large numbers of plant floor devices. Removing these various services from individual applications and providing them in an application server environment offers many benefits to the system designer. The limitation on the number of tags that can be supported is removed, while at the same time loads can be distributed across servers. Code can be reused across applications and using the Plant Model projects can be given a formal structure, which simplifies maintenance and change propagation. The IAS approach to security is robust and offers data model security to industrial applications at the lowest possible level. It extends the Microsoft Windows security model down to the physical equipment layer, providing security attributes that specifically match factory requirements. At this level, data is arranged according to the area model and the plant model. Users still enjoy the same centralised ease of login procedures as the Microsoft model, but IAS expands upon it once clients are inside the system. Carrying the security model down to the equipment and process loop level makes access much more secure. Authorised accessThis security approach is needed because, while plants typically have a lot of highly skilled engineers and technicians who may be capable of making changes in applications, those applications must be secured at a low enough level so that only authorised persons can make adjustments to them at authorised times. Because of the deterministic nature of factory automation, individual skill and authority levels are matched against the role played with any specific piece of equipment or any process loop, not just with individual permissions. For example, a plant manager may have access to any point in a production process, but that does not mean that it would be wise to intervene in a process anytime he or she wishes, since an intervention at an inappropriate time might cause a catastrophic failure. Industrial Application Server is a versatile new product from Wonderware that satisfies the evolving requirements of a maturing automation marketplace. It provides a degree of scalability, integration and architectural freedom that will enable it to be an ideal platform on which users can evolve today's industrial applications. With the advantage of a single name space, as if it were merely one server, IAS in reality uses multiple networked peer-to-peer servers seamlessly integrated to support the thousands of devices found in any plant floor topology. This plant-centred model provides an efficient path forward for integrating today's existing industrial systems with tomorrow's new technologies.
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