OPC UA over TSN – What is it and how did it begin?
07 March 2019
Machines, field devices, ERP systems and cloud applications – all communicating on a single network? An impossible dream until only a few years ago, but with OPC UA over TSN, it will soon be reality. The world's automation companies have agreed on a common standard for real-time industrial communication.
For decades, the automation landscape has been shaped by the effects of competing communication protocols. For machine builders, the choice of a communication protocol was at the same time a commitment to a specific controls vendor. In many cases, the only way to meet their customers' requirements has been to offer multiple variants of the same machine, each with a different control system.
The fieldbuses
"The predecessors of the first fieldbus systems were developed in the late 1980s," explains Stefan Schönegger, vice president of product strategy and innovation at B&R. By the mid-90s, more and more fieldbus systems began stepping into the ring to fight for their share of the market. "This was the beginning of what would become known as the first fieldbus war."
In the late 90s, as increasingly demanding applications began to exhaust the capacity of existing fieldbus technology, eyes turned to the well-established Ethernet physical layer as the most promising alternative. The only obstacle would be finding a way to make Ethernet real-time capable.
The Industrial Ethernet protocols
"For a time, it looked as though the industry might be able to settle on a common Industrial Ethernet standard," says Schönegger. But automation suppliers soon began developing different Industrial Ethernet protocols for each of their systems, and by the early 2000s, machine builders and operators had to abandon the dream of a uniform protocol.
Like its fieldbus predecessors, Industrial Ethernet has its own performance limits, which are becoming a restrictive factor in an increasing number of applications as the years progress. In addition to bandwidth and cycle times, the requirements of the Industrial IoT have been the main driver of demand for a new technology. "A fundamental prerequisite for the IoT is seamless communication from the sensor to the cloud," explains Schönegger. "In this context, security is among the top concerns."
The Shapers first unveiled their plans for a unified communication standard based on OPC UA and TSN at he 2016 SPS IPC Drives exhibition.
The standard
"At B&R, we began thinking about what the next step in the evolution of industrial communication might look like," explains Schönegger. "As we spoke with our customers about their requirements, it quickly became clear that, aside from the technical issues, there was also another major pain point: the heterogeneity of the protocols and the lack of a globally accepted standard."
"So, in September of 2016, B&R and network specialist TTTech invited interested automation and IT companies to talk about the establishment of such a standard based on OPC UA and the Ethernet extension TSN," recalls Schönegger. It was at this meeting that the OPC UA TSN initiative was founded. Its members would later become known as the "Shapers". The group's vision was to achieve open, interface-free communication from the sensor to the cloud – including the real-time capabilities needed for highly synchronised motion control. The goal was to offer increase performance by a factor of 18 compared to existing technologies.
From that point on, the Shapers grew steadily in number as they hashed out the technical details of the new technology. "By 2018, many of the biggest names in automation technology had joined our initiative," reports Schönegger. "The industry had come to accept that the only way forward is with OPC UA over TSN as a unified standard."
The organisation
For a standard to be independent, the organisation behind it must not be tied to any specific manufacturer. "I am thrilled that the Shapers have been able to win over the OPC Foundation as the umbrella organisation for OPC UA over TSN," says Schönegger. In November 2018, the OPC Foundation announced that it would expand its scope down to the field level with OPC UA over TSN and set up a steering committee for the new technology comprising 22 industry heavyweights. In addition, three global players in automation were added to the board of the OPC Foundation: Schneider Electric, Rockwell and B&R's parent company ABB.
The future
B&R presented the first bus controller with OPC UA over TSN at the 2018 SPS IPC Drives exhibition.
The fundamental specifications for OPC UA's publish-subscribe mechanism and the essential sub-standards for TSN have been completed. These include IEEE802.1AS for time synchronisation and IEEE802.1qbv for the guaranteed transmission times for data on the network. "Our efforts are now already focused on equipping our entire portfolio for OPC UA over TSN," explains Schönegger. A B&R bus controller with OPC UA over TSN is set to go into production, and controllers and drives will follow.
"In a few years' time, you won't find a new machine without OPC UA over TSN," Schönegger is confident. As the barriers of the heterogeneous protocol landscape fall, machine builders and operators will have a much easier time implementing connected manufacturing systems and Industrial IoT solutions. Schönegger expects the transition phase to go smoothly. "Companion specifications such as those between POWERLINK and OPC UA," he notes, "make it easy to integrate existing machines and systems into new networks."
OPC UA over TSN – How it all began
• September 2016: Foundation of the OPC UA TSN initiative at the invitation of network specialist TTTech and automation specialist B&R. The companies involved would later became known as the "Shapers".
• April 2017: Belden/Hirschmann and Phoenix Contact join the Shapers.
• November 2017: Pilz, Hilscher and Wago join the Shapers.
• April 2018: Rockwell Automation announces it has joined the Shapers.
• November 2018: The OPC Foundation announces its expansion into field-level communication with OPC UA over TSN.
• November 2018: ABB, Schneider and Rockwell join the board of the OPC Foundation.
• November 2018: Presentation of the steering committee for OPC UA over TSN at the field level: ABB, BECKHOFF, Bosch-Rexroth, B&R, Cisco, Hilscher, Hirschmann, Huawei, Intel, Kalycito, KUKA, Mitsubishi Electric, Molex, Omron, Phoenix Contact, Pilz, Rockwell Automation, Schneider Electric, Siemens, TTTech, Wago and Yokogawa.
• November 2018: The first functional devices with OPC UA TSN are presented at the SPS IPC Drives exhibition.
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