OPC UA over TSN: A Realistic Future for a Unified Industrial Control Network?

  • May 08, 2018
  • Feature
OPC UA over TSN: A Realistic Future for a Unified Industrial Control Network?
OPC UA over TSN: A Realistic Future for a Unified Industrial Control Network?

By Bill Lydon, Editor, Automation.com

At Hannover Fair 2018, the vision for a seamless architecture from edge devices to enterprise and cloud computing was a prominent theme. Numerous product demonstrations, announcements, and discussions promoted the combination of Time Sensitive Networking (TSN IEEE 802.1) with OPC UA messaging and data models to create a new manufacturing and production architecture to satisfy Industry 4.0, Industrial Internet of Things (IIoT), and Internet of Things (IoT) requirements.  The vision of this new architecture is made possible with high-performance deterministic TSN to enable implementation of Industry 4.0, Industrial Internet of Things, and Internet of Things requirements, including strong data typing and information models at edge devices including sensors and control devices (i.e. circuit breakers, motor starters, etc.)   Adoption of this architecture would help achieve the goals expressed by many users to have multi-vendor peer-to-peer communications and control between and sensors and control devices, PLCs, and DCS controllers without cumbersome gateways and bridges. Thus this vision would also create a seamless architecture from edge devices to enterprise and cloud computing.

If implemented this would eliminate the need for existing middle level industry protocols such as EtherNET/IP (CIP), PowerLink, SERCOS, PROFINET, and others.


An Ad Hoc Group of Industry Leaders

This initiative is not championed by any formal trade association or a sanctioned working group under IEEE, but rather it is an ad hoc group of companies meeting to sort out industrial insights. These companies include Rockwell Automation, ABB, Belden, Bosch Rexroth, B&R, Cisco, Hilscher, KUKA, National Instruments, Parker Hannifin, Phoenix Contact, Pilz, Schneider Electric, TTTech, and WAGO.  This ad hoc group is referring to themselves as the, “Shapers”, due to the focus on the time shaping functions for TSN IEEE 802.1.

Members of the Ad Hoc group calling themselves “Shapers”.


Goals of the Shapers’ Efforts

The goal of the effort was described by “Shapers” group member TTTech as follows:

The communication platform OPC UA (Open Platform Communication Unified Architecture), which enables data exchange from sensor to cloud, has been chosen as the reference standard for Industry 4.0. The Publish/Subscribe enhancement for OPC UA now allows for multicast communication between thousands of sensors and the cloud, and also coordination between machines. OPC UA in combination with IEEE TSN enables open data exchange between industrial controllers from different vendors, making the vision of open, real-time machine to machine communication a reality for all applications, including those with critical safety requirements.  

In April, Rockwell Automation joined the industry effort on OPC UA Time-Sensitive Networking. At the time, Paul Brooks, business development manager, Rockwell Automation was quoted, “Connecting technologies across an industrial organization while maintaining multivendor interoperability requires a harmonized, interoperable solution that uses consistent information models, communication and application behavior (together known as application profiles),”


Industrial Internet Consortium (IIC) White Paper

At the time of the release, Rockwell Automation also referred to an Industrial Internet Consortium (IIC) white paper titled,Time Sensitive Networks for Flexible, Manufacturing Testbed - Description of Converged Traffic Types.

The conclusions of this white paper noted several aspects of TSN potentially applied to manufacturing, including types of traffic found in typical manufacturing IACS (Industrial Automation & Control Systems) and the network performance characteristics they need. In a future release, the paper will be expanded to include mappings of the traffic types and performance characteristics to QoS capabilities, including the enhanced TSN capabilities. This mapping is intended to help the underlying standards organizations to deliver interoperable and certifiable devices and network infrastructure to the industry overall.

Some of the many industry minds behind this whitepaper included:

  • Paul Didier -CISCO
  • Astrit Ademaj -TTTech
  • David Puffer -B&R Automation
  • Dietmar Bruckner -B&R Automation
  • George Ditzel -Schneider Electric
  • Ludwig Leurs -Bosch Rexroth
  • Marius-Petru Stanica -ABB
  • René Hummen - Belden/Hirschmann
  • Richard Blair - Schneider Electric
  • Thomas Enzinger - B&R Automation
  • Florian Frick – ISW
  • Jeff Lund -Belden/Hirschmann


Bill’s Thoughts & Observations

I find the lack of organization of the “Shapers” effort to be, at a minimum, unusual.  This group would logically fit as part of the OPC Foundation, since the streamlined architecture would only have TSN and OPC UA to accomplish the task.

Will TSN become mainstream for industrial automation?  Time Sensitive Networking (TSN IEEE 802.1) for industrial automation has potential to be a unifying network but has a level of complexity that could have a negative impact on network reliability.  There are many unanswered questions about TSN that have been explored in the references at the end of this article.

The cost of applying TSN could be significant as well.   In meetings with Cisco at Hannover Fair 2018, I was told TSN ethernet switches are more expensive with the added TSN capabilities I asked for list price comparisons, but CISCO informed me they do not release price lists outside of authorized Cisco sellers.  CISCO spokespeople provided the following information on the cost issue:

“We expect the current TSN market to grow and will be adopted on additional platforms. All shipping IE4000 ( CISCO Industrial Ethernet Series ) switches support TSN. There is no IE4000 without TSN support and customers can download firmware for previously purchased IE4000 switches and make them TSN capable.  There will be a software license to use TSN in production. The price of the TSN license will be no more than 25% of the price of the Switch.”

Possibly over a long period of time the complexity could be reduced to a chip…if TSN gains enough popularity to achieved high volume use.  It is not at all clear, at this point in time, that TSN will become a mainstream volume adopted technology since there are competing approaches that are emerging for automotive and other applications.

Many of the vendors involved in the aforementioned TSN efforts are not addressing multivendor control and application portability. This is a big issue for users.  Further, the majority of the participating vendors have not implemented the PLCopen/OPC Foundation published IEC 61131-3 OPC UA Function Blocks. These are intended to enhance data exchange and peer to peer control and automation between controllers, independently from fieldbus system or vertically, with other devices accomplishing multivendor interoperability at the applications level.


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