OPC stands for Open Platform Communications and is one of the most important communication standards for Industry 4.0 and the IIoT.

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Michelle Kiener ABB Review Zürich, Switzerland, michelle.kiener@ch.abb.com

With OPC, access to machines, devices and other systems in the industrial environment is standardized and enables similar and manufacturer-­independent data exchange in the industrial automation domain and other industries. The specifications provide separate definitions for accessing process data, alarms and historical data:
• OPC Data Access (OPC DA) defines the exchange of data including values, time and quality information.
• OPC Alarms & Events (OPC AE) defines the exchange of alarm and event type message information, as well as variable states and state management.
• OPC Historical Data Access (OPC DA) defines query methods and analytics that may be applied to historical, time-stamped data.

The OPC Foundation is the organization behind the standard and counts ABB among its 850 plus members. Founded in 1994, the first version of the OPC standard was released in 1996. Membership of the foundation is not required for the use of OPC UA technology.

UA Unified Architecture
The UA in OPC UA stands for Unified Architecture and refers to the latest specification of the standard which was released in 2008. Although OPC UA is functionally equivalent to its predecessor, now called OPC Classic, it enhances and surpasses its capabilities by being a platform-independent service-oriented architecture [1] which has moved away from COM/DCOM to purely binary TCP/IP or alternatively Simple Object Access Protocol (SOAP). OPC UA integrates all the functionality of the classic OPC specifications into one extensible framework. Integration between OPC UA products and OPC Classic products can be accomplished with COM/Proxy wrappers that are available from the OPC Foundation.

01 Connectivity islands linked by OPC UA.
01 Connectivity islands linked by OPC UA.

In addition to many other improvements, OPC UA supports semantic data description and was developed to be “firewall-friendly” ie, it can be managed and steered using standard network techniques. 128 or 256 bit encryptions are used to secure data during transmission, as well as certificate exchange, sequenced packets and message signing, amongst other techniques.

The multi-layered architecture of OPC UA is intended to provide a “future proof” framework, capable of incorporating, for example, new security algorithms or transport protocols, whilst also maintaining backwards compatibility.

Within organizations one will always find islands of data and they don’t necessarily share information between them easily. OPC UA overcomes this and makes it very easy to move data between enterprise systems and monitoring devices and sensors that interact with real world data →01. One of the key features of OPC UA is that it can be supported on a wide range of components from low end sensors and tiny embedded controllers to high end servers, making it an important and useful standard that can be widely applied to connect and share between the data islands. 

[1] OPC Technologies Unified Architecture. Available: https://opcfoundation.org/about/opc-technologies/opc-ua/ [Accessed November 15, 2022].
Title photo: ©Andrey Armyagov/stock.adobe.com


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