Whatever happened to Time Sensitive Networking (TSN)? I had been pondering the relative disappearance of several technologies creating buzz in 2020—TSN, Arduino, Raspberry Pi. Then came buried within the OPC Foundation discussion with us at the 25th ARC Industry Forum this month word of TSN.

This appears to be the last of the updates I received at ARC this year. OPCF president Stefan Hoppe began with a photo of the unusual amount of snow around his house in Germany (as I was contemplating my yard in my new house in the Chicago suburbs with about 2 feet of snow blanketing the area. Meaning—none of us were in Florida this year).

I wrote last month about the Field Level Communications standard work. In this, 300 experts from 60 major companies published a Technical Paper and completed Initial Release Candidate. OPCF continues work on the networking side with this FLC specification along with work on the “Advanced Physical Layer”, which is a new Ethernet cabling standard. Hoppe stated the mission, “…in order to drive industrial interoperability from field to cloud (and vice versa) and to support IT/OT convergence.”

Work has also started on identifying and creating facets and profiles that define the mandatory feature sets for the various types of automation components which is essential to reach a high level of cross-vendor interoperability.

Hoppe continued, “Ethernet APL and TSN are important enablers, which allow OPC UA to further penetrate new application areas in process and factory automation. The OPC Foundation’s Field Level Communications Initiative bundles these activities and acts as a global center of gravity for a unified OPC UA-based industrial interoperability solution harmonized between the process industry and factory automation.”

Peter Lutz, Director of the FLC Initiative, said, “The initial release candidate, which was completed in November 2020, is a major achievement because it facilitates the long-awaited standardization of Controller-to-Controller (C2C) connectivity. The specifications are used not only to build prototypes, they are also used to create test specifications that will be converted to corresponding test cases for the OPC UA certification tool (CTT). Furthermore, it lays the foundation for specification enhancements, covering the Controller-to-Device (C2D) and Device-to-Device (D2D) use cases in the next step.”

The initial release candidate (RC1), which focuses on Controller-to-Controller (C2C), consists of four parts (Parts 80-83) that specify how automation controllers exchange process data and configuration data using OPC UA Client/Server and PubSub extensions in combination with peer-to-peer connections and basic diagnostics.

These parts are extensions to the OPC UA framework and are labelled with OPC UA FX (Field eXchange):

  • Part 80 (OPC UA FX 10000-80) provides an overview and introduces the basic concepts of using OPC UA for Field eXchange.
  • Part 81 (OPC UA FX 10000-81) specifies the base information model and the communication concepts to meet the various use cases and requirements of Factory and Process Automation. 
  • Part 82 (OPC UA FX 10000-82) describes networking services, such as topology discovery and time synchronization.
  • Part 83 (OPC UA FX 10000-83) describes the data structures for sharing information required for Offline Engineering using descriptors and descriptor packages.

In addition, a 40-page technical paper was published that explains the overall vision and the technical approach.

Since the Advanced Physical Layer (APL) and Time-Sensitive Networking (TSN) are key technologies for the OPC Foundation’s strategy to bring OPC UA down to the field in discrete and process industries, different cooperation strategies have been established:

  • The OPC Foundation has joined the Advanced Physical Layer Project Group (APL) to support the development and promotion of the Advanced Physical Layer (APL) for Industrial Ethernet, suitable for use in demanding applications and hazardous locations in the process industry.
  • The OPC Foundation has established liaisons with IEC SC65C as well as IEEE 802.1 in order to support and align with the IEC/IEEE 60802 TSN Profile for Industrial Automation, which is essential in building converged industrial automation networks in which multiple IT and OT protocols share a common network infrastructure. 
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