With the release of the OPC Unified Architecture, the OPC Foundation has finished a five-year development process of the new standardized communication and information exchange platform. The new architecture incorporates proven concepts from the successful OPC standards for access to current data, alarms and events, and historical data, but unifies them and provides solution for additional OPC use cases. Platform-independent technology allows the deployment of OPC UA beyond current OPC applications only running on Microsoft Windows-based PC systems. OPC UA can be directly integrated into embedded systems as well as into Linux/UNIX-based enterprise systems. The provided information can be generically modelled and therefore arbitrary information models can be provided using OPC UA.
The results of the specification and intensive verification work are implementable specifications, communication stacks and SDKs in multiple programming languages and higher level third-party toolkits. Early adopters of the standard verified products ranging from embedded OPC UA servers up to OPC clients integrated into enterprise systems on several OPC UA plug-fest events and interoperability workshops.
The key feature of OPC UA for the use in embedded systems is the platform neutral communication infrastructure based on service oriented architecture and web services. A highly optimized binary version of web services ensures high performance and minimal resource consumption on embedded systems. Platform-independent in this context does not only mean operating system independent, it is also independent of the programming language used and development environment. The OPC UA communication stacks are already implemented in a portable ANSI C version, in C# for the .NET platform and in JAVA. Even developers on a Windows-based platform will have great advantages using the highly optimized communication stack and the firewall friendly communication, which can be scaled and tailored to the particular needs of the application.
With the ANSI C version, the OPC UA communication stack can be implemented directly on embedded systems, allowing OPC data services to be tightly coupled with real-time control applications. This arrangement reduces resource requirements and avoids state inconsistencies. OPC UA on embedded systems eliminates the fundamental limitation of traditional OPC systems, requiring running the OPC interface on Windows PC platforms using a COM/DCOM communication interface. The classic OPC setup requires a proprietary communication channel from the embedded system to the Windows PC running the OPC interface and a parallel configuration of the OPC server on the PC. This leads to additional engineering effort and has a potential for inconsistencies in the configuration between the embedded system and the OPC server.
The direct integration of the OPC interface into the automation system avoids gateway solutions, significantly reduces the cost and complexity of OPC systems and simultaneously improves their reliability. Solutions like an OPC UA server in an embedded controller, an OPC UA server and client in a SCADA system running on a Windows PC, or an OPC UA client in an enterprise system running on a UNIX OS will be possible with the new OPC UA communication infrastructure.
As well, the modelling capabilities of OPC Unified Architecture will be used in embedded systems. A joint working group with PLCopen is defining an OPC UA information model to standardize access to controllers programmed with the IEC 61131-3 programming languages. The OPC UA Device Integration model provides a standard for device configuration and diagnostics. Such standardized information models allow vendors of embedded systems to directly integrate the systems into an OPC UA communication infrastructure, and also to expose the information from the embedded system in a standardized manner.
Unified Automation, a provider of OPC automation components and development tools, is a leader in providing ANSI C and C++ cross-platform embedded development products and services for OPC UA. The offered OPC UA SDKs, Toolkits and services allow easy and fast development of embedded solutions. The complete implementation down to the cable is available in source code, with no pitfalls and no surprises. Nearly 20 companies are successfully using the OPC UA SDKs of Unified Automation. There are already products for platforms like Windows and Windows CE, Linux and Unix on the market. In the very near future we will see embedded OPC UA products on RTOS like Euros, TenAsys INtime, VxWorks, embedded Linux, and others.
The communication stack and the cross-platform SDK were proven for development of OPC UA applications on various platforms. From standard x86, Intel Atom and several ARM processors to multi-core architecture, the concepts have been proven by ascolab GMBH, a key player in the OPC UA core development team. “We have left behind the concept studies and prototyping phase; ...