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OPC UA Explained
Quickstarts and Tools for Developers
I have been amazed lately at some of the technological advances in consumer electronics that I have been seeing on television. Handhelds that have Google built right in. An HP printer that has Google built right into it that allows users to print images and documents directly from the internet or wireless device. Truly amazing advances in technology that provide new levels of connectivity for end-users to stay completely connected to their environment. Have you ever stopped to wonder how trends in consumer electronics influence trends in other parts of our lives? As a society we are demanding to be completely connected to the web and each other in all our work and social environments. Just ask anyone who is a fan of SMS text messages.
“Staying connected” has an entirely new meaning. Those who travel a lot are used to hauling around laptops and searching for a power outlet to stay connected and access email. With the recent advances in handheld technology consumers can stay connected with business and family directly from cell phones and other handhelds. WiFi connections are abundant and customers of coffee shops and other retail outlets demand them. As I mentioned earlier, every device that is sold on the consumer market is coming with some sort of built in connectivity to the web, or an ability to wirelessly interface with other devices. The desire for web services in consumer electronics is extremely high, and that desire transfers over into industrial communication protocols too.
OPC UA (Unified Architecture)
At the OPC Foundation we receive a lot of questions about OPC UA (Unified Architecture). Is OPC UA simply OPC DA in a different wrapper? As with advances in Microsoft Windows, not every technological advance is on the side of the box. Often advances in security and functionality are powerful, but too small or complex to be stated on the box for consumers. To answer the question - OPC UA is an advance on OPC technology. It is the next evolution in the OPC specification and will serve as the foundation for all new specifications in the future.
OPC UA is actually an abstract framework with a multi-layered architecture where each layer is completely abstracted from its neighboring layers. These layers define the protocols that hit the wire, the security to encode/decode messages containing your data, data-type definitions and much more. With this framework of core services and data-types, one can very easily build upon (inherit) them to add more functionality. This allows OPC UA to combine the best features and functionality from the current (OPC Classic) specifications and takes them to the next level by adding a Service Oriented Architecture (SOA), and a whole world of security features to make those die-hard security gurus happy.
Because of the abstract layering of the OPC UA architecture, it will be possible to add new over-the-wire Protocols, to add new Security and Encryption technologies, to add new data types (simple and complex). So as the world evolves and the way we do things changes, OPC UA will be able to advance with it.
All about OPC UA Profiles
OPC UA already encompasses all of the current (Classic) OPC specifications: OPC DA (Data Access), A&E (Alarms and Events), HDA (Historical Data Access), as well as Commands and complex data. This complexity is made easy for users of OPC UA by providing them with a means to choose the level of functionality that is right for them. OPC UA will provide “Profiles” to enable this customized functionality. Each of the OPC Classic specifications can be considered a “Profile”.
OPC UA will become the “transport”. Other protocols/standards such as BACnet could very easily become a Profile within OPC UA. This would mean that a device could simply expose a UA Server sporting a “BACnet Profile” and any UA Client would be able to consume its data.
The addition of web services enables OPC UA to be platform independent, and truly scalable. There has been a huge demand from both end-users and vendors over the last few years to implement OPC on non-Microsoft based computer systems, and embedded devices alike.
OPC UA Functionality
OPC UA offers all the functionality that end-users were used to with OPC Classic but without the constraints. Flexibility and scalability are key characteristics for OPC UA. Most importantly, OPC remains an open international standard for reliable interoperability and data exchange.
Imagine a day where inexpensive embedded devices have OPC UA built straight into them. Imagine a day where Linux, MAC and Windows UA products are talking to each other without special configurations. Both of these concepts are already a reality on the open market making the future of OPC UA now!
Oh, and did we forget to mention that OPC UA products built today with today’s technology will still work with those products built in the future? Just as they’ll seamlessly work with the OPC Classic products we’ve been using for the past decade.
Guide to OPC UA Downloads
Questions abound about OPC UA. Particularly end-users can find tools and guides to OPC UA. Randy Armstrong of the OPC Foundation published a post on his blog that highlights several useful tools and guides for those wanting more knowledge.
Here is an excerpt from his Blog.
Top Questions and Answers about OPC UA (Click on the blue hyperlinks for more information.)
I am new to the world of OPC UA and I am looking for a somewhere to start?
Armstrong Answers: For people looking for a good introduction to UA concepts I recommend the video/audio presentations from UA DevCon 2007. They can be found here.
I am a software developer and want to see the actual code that can get me
started with OPC UA?
Armstrong Answers: For coders looking for a simple starting point there are a series of Quickstarts available. Each Quickstart contains one or two simple applications which focus on a particular feature. For example, the Data Access Quickstart contains a client and server that implement nothing more than the features which you would see in a COM DA application (e.g. browse, read, write, subscribe). The Alarm Condition Quickstart provides the equivalent based on COM AE applications.
I am looking for help developing C/C++ applications. What can the OPC
Foundation do for me?
Armstrong Answers: The ANSI C stack source code is part of the SDK source download but it is also available in a separate package which does not include the .NET SDK. There is an ANSI C Quickstart which provides simple C++ client and server applications. These applications illustrate how to create a session and read a value.
I need to develop Java applications, is that possible using OPC UA?
Armstrong Answers: The Java stack is available from the OPC Foundation here.
(To read more in the OPC UA Blog, navigate to: http://lists.opcfoundation.org/RandyBlog/default.aspx)
Earlier we spoke about the
influence of consumer electronics on the world of industrial technologies. The
expectation has been set with respect to consumer electronics and plug-and-play
interoperability. Engineers are expecting the same level of interoperability in
their industry. OPC UA will continue to provide the standard infrastructure
enabling secure and reliable plug-and-play interoperability. OPC UA will also
continue to enable end-users to have the ability to pick best-of-breed
components to build the systems they want without being locked into one vendor’s
proprietary protocol or hardware.
Systems architects and Integrators must choose carefully when advising on system construction. In today’s economy the maximizing of assets is paramount. Systems need to be constructed with not only today’s needs in mind, but also what tomorrow's might be.
Looking for more information about OPC Unified Architecture? Check out the latest OPC UA news and developments at the official OPC Foundation website: www.opcfoundation.org or at Randy Armstrong’s OPC UA Blog: http://lists.opcfoundation.org/RandyBlog/default.aspx
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