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  May, 2007
OPC – Paving the Road to Interoperability
by Eric Murphy

When the majority of the top Fortune 500 companies are using a technology, it’s usually safe to say it’s more than just a coincidence. Companies like ExxonMobil, Wal-Mart, Ford, General Electric, Dell and Pfizer span a wide range of industries and businesses who are using OPC to solve the their problems. So what is driving OPC?

OPC fulfills a need that many companies are striving for: Interoperability and integration of their information systems. Interoperability can be defined as “the ability of applications and systems to share information and exchange services with each other based on standards and to cooperate in processes using the information and services”. To put it more simply: Everyone gets the data, shares the data, understands the data and uses the information in a standard way. This is important to many companies for different reasons. Those working with reduced inventories require increased response times. Those who need better planning and decision making, require access to accurate and current information. Those looking for improved consistency and quality, require more automated business processes. Those facing increased customer service and compliance reporting demands require access to additional information. All roads lead to improved interoperability, and OPC is paving the way.

The term OPC has grown in scope over the last ten years. For many, OPC refers to the classic OPC standards that standardize information exchange for process data. These specifications are based on Microsoft’s COM/DCOM technology, and represent many thousands of OPC based products and installations, across industries and around the globe. More recently, the term OPC also includes the newly released OPC UA (Unified Architecture) standard. OPC UA is based on a platform independent, service-based architecture and has been designed to extend OPC to address the needs of enterprise level interoperability. Members of the OPC Early Adopters implementation group include many of the major control systems and OPC product vendors. This strong backing reflects the commitment to ensuring OPC UA enjoys the same level of success and adoption as the current OPC

specifications. OPC UA is the targeted as the architecture of the near future, but what is it about OPC today that is driving big name companies to make it their connectivity standard?

OPC Enables Integration

Regardless of what business a company is in, market dynamics are demanding faster response times and more efficient decision making. Customers need more data, faster, derived from multiple sources and delivered simultaneously to many destinations. In order to achieve the benefits of flexible, scalable and interoperable systems, without high integration costs and time, the solution must also be standardized across multiple vendors, systems and products. That is the challenge OPC successfully addresses.

In a nutshell, OPC provides a functional interface for reading and writing data in an efficient and deterministic way. There are separate specifications to address different data semantics, including real-time data, historical data, alarm and event information and batch data. The interfaces are comprehensive enough to provide the functionality that users require, yet simple and practical to implement, which results in wide vendor acceptance. The OPC specifications are implemented on Microsoft’s distributed binary communication protocol, DCOM. This offers several advantages, including high speed data transfer capability, efficient handling of multiple client/server connections and built-in operating system level security. In addition, many of the major control systems, machine interfaces, historians, expert systems and other automation applications are widely deployed on the Microsoft Windows platforms. Proper adherence to the OPC standards is aided by the OPC Foundation Compliance Testing tools and product interoperability sessions. These factors have led to the creation of fast, flexible and reliable connectivity solutions that businesses require.

OPC UA Drives Interoperability

Since OPC offers so much in the way of connectivity, it begs the question ‘Why introduce OPC UA?’ The primary purpose of the classic OPC was to solve the integration problem between devices and PC based client applications. The automation industry’s desire for connectivity standardization has led to OPC being used in a wider range of applications than was originally considered. The scope now extends to enterprise level interoperability, which includes applications from the field level all the way to realm of Enterprise Report Planning software, across multiple hardware platforms, and in globally diverse installations. As technology and market requirements change, so must the interoperability standards, therefore OPC UA extends the scope of the classic OPC specifications. The single OPC UA architecture encompasses and unifies the functional data format for real-time, historical, event based and batch information. The OPC UA specifications also go farther in setting standards for application security, reliability, audit tracking and information management. These are key components in an interoperable enterprise architecture.

The OPC UA specifications are implemented on a service base architecture, which leverages existing standards such as XML, SOAP and the WS initiatives. Services based implementations are supported by Microsoft as well as many other operating systems. This means OPC UA will be available on more platforms, including embedded operating systems. This promotes the power of standard based connectivity across more layers of the enterprise. A service based model also allows OPC UA to leverage standard security aspects such as authentication, encryption, data integrity and auditing. These are important features for companies facing increased security requirements.

In addition to extending, unifying and allowing backwards compatibility with existing OPC products, OPC UA offers a rich information model to better transform the data into information. Not only does OPC UA allow access to multiple data sources and formats, the architecture also supports reference semantics so client applications can discover and understand the information they are collecting. These capabilities offer the promise of more powerful OPC UA client applications in the future. The same flexible, secure interfaces could be available on a smart transmitter, the control system operator station, the historian, maintenance database and the manufacturing execution system; A single interoperable data highway from the shop floor to the top floor.

When traveling any road it’s important to know where you are coming from, as well as have clear sight of where you are heading to. OPC is firmly grounded in a successful history of standardizing integration for the automation industry. OPC UA is clearly well equipped for the complex highways of next generation enterprise interoperability. On the road of business, companies rely on those who pave the way to provide the infrastructure needed to drive their success.

© Copyright 2007, Matrikon Inc.

Eric Murphy is Advanced Architecture System Design Engineer, MatrikonOPC. Eric Murphy,BSc, PEng (Alberta), Eric is a Chemical Engineer with a Process Control specialization and an OPC expert. Eric has been a part of the OPC community since its early beginnings in the mid-1990s. Eric is heavily involved with the OPC Foundation and currently acts as the chair for the OPC Historical Data Access (HDA) working group. Eric is also a member of the OPC Technical Steering Committee (TSC) and an active member of the OPC Unified Architecture (UA) working group. Eric's Contact Information

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