OPC UA: The United Nations of Automation
A global standard for industrial interoperability with common data models
By Stefan Hoppe
OPC UA is a framework for industrial interoperability based on data models that provide a syntactical definition of information that can be communicated with virtually any communication methods, including modern industrial protocols, Ethernet, cellular, and wireless. Device and machine manufacturers describe the object-oriented information of their system and also deﬁne the access rights with integrated information technology (IT) security. International security experts have proven this end-to-end, built-in-by-design security with very positive and transparent results. Data producers, like machine builders, thus remain in control of their data and can distribute it in a targeted and controlled manner. They thus also participate in big data and the analysis of their data to achieve increased efficiency and performance, yielding greater manufacturing and production profits.
There are many protocols, but OPC UA’s goal is common information modeling that can be used throughout automation systems to achieve seamless interoperability. The actual key for digitalization lies in the meaning and description of the data, and OPC UA provides a framework and standards for information modeling. Unconsciously, every equipment and machine manufacturer today provides an information model. Data and interfaces are already available (via various protocols). We humans have adapted to the way computers “think” and have created documentation about the meaning behind the bits and bytes and hex codes. The new world of devices enabled by service-oriented architecture (SOA) now helps humans understand “things” faster and easier, because these “services,” above all, offer their meaning.
The subject of SOA is not new in the IT world—but now SOA is moving into the “things” themselves. In the next step, it would be pleasant if different manufacturers who supply the same devices also agreed on the same data and services. The integration of these devices would be much easier and would provide a plug-and-play solution. This is exactly what the OPC Foundation, with many partners, provides in the joint creation of standardized information models (Companion Speciﬁcations).
Before a device and machine builder starts, it should check whether a standardized information model already exists. This interoperability is demanded by more and more operators from different areas of the factory and process industry, but also from the energy or logistics industry—OPC UA has even found its way into industrial kitchen equipment (Association HKI).
Figure 1. Architecture of OPC UA
Membership growth unabated
A few years ago, the OPC Foundation was still a meeting place for technology experts, but today, the global association is welcoming an increasing number of new members from the OPC-UA user community. The number of affiliated companies is rapidly growing. Currently, the list of OPC-UA members amounts to more than 700 globally. It is very gratifying to see that more and more end users are turning to the Foundation. Companies such as Volkswagen, Foxconn, Samsung, Miele, and British American Tobacco from factory automation, but also Equinor, Exor, Exxon Mobil, and Bayer from process automation are demanding the functionalities of OPC UA in their automation environments. They are thus pushing the development of topics with a strong background and sometimes at breakneck speed. For example, the first, more intensive contact with Volkswagen took place in 2017. After becoming an OPC member in 2018, the company hosted an OPC Day Automotive in spring 2019 with over 300 participants in their headquarters in Wolfsburg, Germany.
Their goal is to influence the direction of specifications to make sure technology brings real value for their needs in factories. The OPC Foundation is where all automation manufacturers and also chip vendors like Intel and NXP or IT companies like Microsoft, SAP, and Cisco meet to cooperate on common standardizations. Connecting a machine or a device within minutes to their systems with standardized data and interfaces and integrated security proven by international experts are unique selling points. This helps to achieve plug and play and simplifies industrial automation installation, commissioning, and production startups.
In summary, the OPC Foundation is the United Nations of automation. Companies meet on neutral ground with rules, transparency, and openness. The board of directors is democratically elected by members (not influenced by money); sample code and specifications (once released) are publicly available; and certification is a (paid) service for nonmembers.
Security at all levels
OPC UA offers integrated security from the ground up. An analysis by the German Federal Office for Information Security (BSI) underlines that this is much more than just a marketing slogan. The BSI experts have intensively studied the specifications and stack implementations of OPC UA and concluded that OPC UA offers a high degree of security. All security methods are available!
However, these methods must be implemented comprehensively and above all correctly by the users. Even the best lock in the world is useless if it is not locked or the key is not easily accessible.
Evolution: Combine technologies to cover more applications
The OPC UA framework is similar to a modular system of Lego bricks that can be extended. It is not a revolution, but is normal technology development to combine existing technologies and use their strength for new applications:
- In 2007, OPC UA started with the client/server communication architecture based on Transmission Control Protocol/Hypertext Transfer Protocol Secure (TCP/HTTPS) without any break in compatibility.
- In 2014, an additional communication scheme, “Publisher/Subscribe,” was launched to enable and optimize OPC UA for one-to-many, many-to-one, or many-to-many system configurations. Specifications and validation with prototyping led in February 2018 to the release of v1.04 with User Datagram Protocol (UDP) for faster real-time communication on premise and Message Queuing Telemetry Transport/Advanced Message Queuing Protocol (MQTT/AMQP) as transport for cloud applications. OPC UA data models can be used with any transport and protocol, for example MQTT.
- In 2015, the Time Sensitive Network (TSN) working group with more than 85 members was founded as a subgroup of the OPC UA core team. This project will add a transport mapping from OPC UA Pub-Sub to Time Sensitive Networking. Based on this mapping, deterministic data exchange between UA applications will be possible once TSN is finally specified and operational by IEEE/IEC. Also on the radar is 5G wireless. Fifth generation wireless systems will offer better performance and determinism—mapping Pub-Sub to 5G protocols is considered similar to TSN mapping, ideally with the same or similar configuration interfaces.
- In February 2018, a new group, “Safety over OPC UA based on PROFISafe,” was formed to enable functional safety over OPC UA via client/server and Pub-Sub communication. Today, the group “Safety of OPC UA” is combined in the Field Level Communications (FLC) activities.
- In November 2018, the FLC initiative was formally launched and is now supported by 25 companies providing additional financial and human resources. The aim of this initiative is to extend OPC UA to all relevant industrial automation applications for process and factory automation, including deterministic, safety, and motion.
- In the future, the Advanced Physical Layer (APL) will be combined with OPC UA to provide small devices in process automation, such as flowmeters, with a single cable for power, and to transfer secured data in standardized format directly from data source.
Information is key: Companion specifications
One perfect example is the first global OPC UA Machine Vision Companion Specification, as this has been the first OPC UA Companion Specification developed via close international collaboration between multinational machine vision–related standards bodies, including the American AIA, Chinese CMVU, European VDMA and EMVA, and Japanese JIIA. This “big thinking” aligns well with a key OPC Foundation focus on encouraging organizations to work together to reduce the vast number of overlapping “custom” information models into a harmonized set of OPC UA Companion Specifications that will benefit end users and vendors around the world by lowering the barriers to true interoperability.
For equipment suppliers, meeting this type of industry standard does not automatically mean they become exchangeable, as each manufacturer can offer its own special services on top of the standard. Intelligent devices should definitely be able to support multiple information models simultaneously—for example, the dedicated functionalities of an injection molding machine, in addition to the models for energy data or manufacturing execution system (MES) interfaces.
Leading programmable logic controllers (PLCs) can load the machine with understandable information models and expose standardized data and interfaces to the outside world quickly. To reduce the engineering effort, the importance and availability of such industry-specific and multi-industry information models will increase rapidly in the future. It is the key for Industrie 4.0 (also known as Industry 4.0).
Figure 2. OPC Foundation has a wide range of collaborations with more than 50 today that include process automation, factory automation, energy, engineering, industrial kitchen equipment, and IT standards groups.
Harmonizing cross-domain information models
With the increasing success of the implementation of OPC UA, new challenges arise. In addition to the Companion Specification (e.g., the AutoID industry), each industry sector has its own information model—from oil and gas to the process industry and robotics. The application of OPC UA reduces engineering costs in every sector. The fact that the VDMA (the Mechanical Engineering Industry Association, Europe’s largest industry association with 38 trade associations in the mechanical engineering industry) has the topic OPC UA on its agenda in 17 working groups today (and more are on the road) alone shows the current significance of this universal communication model.
This dynamic development creates new challenges for the OPC Foundation. The multitude of defined specifications leads to duplication in some places. The subject of asset management, power management, or firmware updates can be found not only in the machines used in the process industry, but also in robotics or on an oil drilling platform. To meet this requirement, the OPC Foundation established as an important next step a cross-domain harmonization group for the comprehensive modeling of information models within the OPC Foundation. What is now necessary, for example, has been demonstrated in the AutoID industry by merging within a sector and developing a sector-wide Companion Specification.
The next step in interoperability is to examine where similarities exist between the specifications in other areas in order to minimize these overlaps. The aim of this cross-group work within the Foundation is to transfer global data, for example from an MES or energy interface, to a generally available repository one level higher. This will prevent each working group from independently defining data types for identical applications. The outlook for this cross-domain harmonization is a glimpse into the future of the Foundation and at the same time, the greatest challenge (started in July 2019)—one that will definitely not be completed within a year but will be an ongoing process.
As a first fantastic result, all data types and interfaces of all OPC UA specifications and all Companion Specifications are available online in a reference (https://reference.opcfoundation.org/v104).
End-to-end eliminates vulnerabilities
The OPC Foundation and its members are deeply and firmly committed to end-to-end encryption and have not detected any weaknesses in OPC UA that could pose a security risk. The end-to-end functionality is precisely the feature that OPC UA has been using to stay ahead of other systems, such as some broker-based communication. The OPC Foundation has integrated three different security levels into the UA technology, one of which is end-to-end encryption from the sender of the message to the recipient of the message. This approach has proven to be very robust.
According to the BSI, the disclosure of the OPC UA source code is a further factor in this security robustness. The open source approach enables security experts to gain detailed insight and detect vulnerabilities. For example, the security company Kaspersky has made a valuable contribution to a sample code to demonstrate the high security level of OPC UA. This transparency gives the industry that uses it confidence. The OPC Foundation is aware, however, that with all the security features of UA technology, communication is just one piece of the puzzle in an overall solution. If the underlying hardware is backlogged at the chip level, as was often the case with the media in 2018, then even the best and most secure software is powerless. The Foundation must therefore trust in the security of the hardware.
Neutrality leads to UN comparison: Committed to independence and neutrality
The Foundation is 100 percent independent and cannot be dominated by a single company. There is no risk, for example, that the world’s two largest automation companies will take the helm and steer the Foundation according to their will. The voice of a small company is just as important as that of a global corporation. This independence, along with the transparency of the open source solution of UA technology, is the Foundation’s greatest strength—and, at the same time, the only way to achieve worldwide acceptance among companies from a wide variety of industrial sectors.
Nevertheless, the Foundation’s work is not unaffected by global politics and politically initiated economic developments. Like any other association or alliance, the OPC Foundation registers global developments and moods. The Foundation needs to be vigilant and very careful in observing and analyzing the significance this can have on the Foundation’s work and objectives. From the Foundation’s point of view, it is tremendously important to involve as many companies from as many countries as possible, in order to stick to the idea of a universal, globally usable standard.