What is OPC UA and what does OPC UA stand for?

OPC is an acronym for Open Platform Communications. A number of interoperability specifications have been released over the years and in its latest iteration, OPC UA (Open Platform Communications Unified Architecture) integrates all this functionality into a single service oriented architecture. At the same time, it adds essential new features such as platform independence, diagnostics, discovery, rendering of complex information models, security, and reliability. It also provides everything needed for the transmission and interpretation of data and information from the factory or enterprise information system. OPC UA was released as an IEC Standard, IEC 62541 in October 2011.

Why is OPC UA important?

The OPC UA standard brings plug-and-play connectivity to industrial automation. Before OPC UA, application vendors had to develop custom software for every third-party device and application that needed to be integrated into the automation system. OPC UA instead offers open connectivity across products, independent of the hardware or software platforms involved. OPC UA defines a standard way for sharing real-time data, historical data, and alarms & events, reducing integration and total life cycle cost for system implementation.

What are the benefits of OPC UA?

• Object definition library provides contextualized information, not raw data, which enables true interoperability ‘out of the box’ across multiple vendors and device/applications
• Standardized information enables efficient asset performance management
• Open ecosystem avoids vendor lock-in
• Vendors differentiate by additional features and quality; not by proprietary restrictions
• End to end security model allows use across multiple communications networks
• Specifications, sample code etc. are all openly and freely available. No royalties to pay on any runtimes. Membership of the OPC Foundation is not necessary to access resources or certification labs. Modern IPR policy protects not only OPC foundation members, but also all adopters of OPC UA
• Companion specifications can be developed for devices and IT applications and services, providing a single architecture within which both OT and IT systems can interact in a common manner

How is OPC UA different from other protocols such as DDS, AMQP or MQTT?

The first thing to understand is that OPC UA is more than just a protocol. Protocols such as DDS, AMQP or MQTT are concerned with the transfer of data between applications, devices and systems. They achieve this with different levels of intrinsic security, but they do not implicitly provide any context for the data being transferred. Instead, it is up to the user to define the content of the data and because of this, it does not guarantee that the transferred data can be interpreted by a receiving system. 



OPC UA addresses this by including definitions not only of data and information types, but also of the device or application which generated the data using a common object definition library (OPC UA refers to these as ‘companion specifications’). Because of this, any system implementing the OPC UA architecture is guaranteed to be able to natively connect to and interpret data from any device which supports the same companion specs.

In addition to this common object library, OPC UA also addresses security from an end-to-end perspective. As such it can be used with multiple transfer protocols including both client-server and pub-sub protocols like MQTT whilst maintaining data and user security independently of the transport layer.

How does OPC UA drive industry 4.0?

For industry 4.0 to be fully realized, there are several key issues that must be addressed, namely security, interoperability, real time operation and IT-OT integration. OPC UA provides features which address each of these requirements within a single unified architecture model:

• Security

OPC UA provides end to end security, starting with a hardware root of trust within devices, and extending through the transport, application and user security levels. All devices within a system are authenticated, and all communications are signed and encrypted.

How does OPC UA do vs. other industry standards regarding cost/revenue?

Specifications, sample code etc. are all openly and freely available. No royalties to pay on any runtimes. Membership of the OPC Foundation is not necessary to access resources or certification labs. A modern IPR policy protects not only OPC foundation members, but also all adopters of OPC UA.

There is a level of complexity within OPC UA which means there appears to be a steeper learning curve than for some other technologies. In reality this is rarely the case because of the comprehensive nature of the specification. With other technologies users must factor in the learning curves of associated technologies needed in order to build a complete, end to end, secure, resilient, interoperable and open system. Once all of these parallel learning curves are considered, it can be seen that OPC UA is not any more complex or expensive to implement than any other system offering similar capabilities. Indeed, because features are already integrated into the specification, the overall effort required to implement an OPC UA based system can be considerably less than with other approaches.

What are OPC UA’s major applications?

OPC has its origins in the OT layer between smart devices such as PLCs and supervisory systems such as SCADA. Whilst OPC UA remains highly relevant in this area, the object based nature of the architecture mean that the real hotspot is in the interface to SOA based IT systems, which really benefit from the ability to group and define data by asset type, and the richness of the datasets it provides against these asset models.

At the same time, OPC UA is significantly improving the ability for factory floor systems to communicate with each other in a peer-to-peer arrangement. This can significantly increase the efficiency of a production line by eliminating the delays associated with handing production process between machines, whilst also allowing machines that have otherwise incompatible fieldbus or protocol models to interact directly with each other.

How widely adopted is OPC UA?

There are over 450 companies who are members of the OPC foundation. Hundreds more are developers or users of OPC technologies without being foundation members. Users come from OT, IT, academic and research backgrounds, and range from small independent software provides to large multi-national automation corporations. Collaboration groups exist to share resources, knowledge, and promote the OPC UA architecture and its related companion specifications.

How OPC UA enables and simplifies remote facility management?

Let’s start by analyzing the ideal needs of any system targeting remote management. Firstly it must be secure, to ensure that only authorized actors can interact with each other, and can see the data flowing between them. Secondly, it must have the versatility to work over a number of different communication topologies, including some which are subject to occasional dropout. Then, it needs to work with not just a single type of device from a single vendor, but instead with multiple device types from multiple vendors. It also needs to provide an easy way to contextualize the data that is flowing, ideally one which is machine readable rather than requiring human intervention of interpretation. Finally, it needs to interact with multiple systems, both from an IT and OT background. Of course, it is possible to address all of these elements by combining and integrating technology solutions from multiple sources, but OPC UA provides all of this within a single, open and publicly adopted standard. Simply by deciding to base a system architecture on OPC UA, all of these elements are intrinsically available ‘out of the box’, leaving users to concentrate on their application and value add, rather than the mechanics of building an infrastructure.