OPC UA and TSN – Expert Presentations on SPS Connect

Due to the Covid19 pandemic, MESAGO, the organizer and host of the annual SPS-fair in Nuremberg, Germany, conducted the “fair” as a virtual event over 3 days.  They created a web-conference platform that allowed visitors to connect to other visitors, experts and “exhibitors”, presented live stream opening speeches, and had all 3 days fully packed with live stream presentations on automation topics.

The platform MESAGO created for the SPS Connect made a professional and excellent impression, as registration and participation of events was easy.  Of course, this was not a 1:1 replacement of a real exhibition with lots of personal contact opportunities, but given the circumstances, it was the best MESAGO could make out of the situation.

Two of the presentations focused to OPC UA and TSN.  The first presentation “Realtime controller and field level OPC UA over TSN applications” was held by Stefan Bina of B&R Industrial Automation.  After summarizing the advantages of OPC UA and of TSN, the upsides of the different user groups were highlighted, and it is interesting to note, that besides the machine builders and end users (plant owners), data scientists were also mentioned as an important user group.

Next, the roadmap of the OPC Foundation was explained.  In a nutshell, for the C2C – controller to controller – real-time communication based upon OPC UA and TSN, the initial release candidate (RC1) specification has been completed by the OPC Foundation.  B&R's OPC UA over TSN enabled portfolio includes X20 PLCs, bus controllers, industrial PCs, panel PCs, and a TSN machine switch.  Configuration of OPC UA over TSN devices and the network itself, as well as assignment of access rights, is all handled in B&R's Automation Studio engineering software.

In the following presentation it became evident why motion control products are not yet available, and this is due to the roadmap of the OPC Foundation FLC initiative.  The second presentation on OPC UA over TSN was held by Peter Lutz, director of the FLC (field level control) initiative of the OPC Foundation.  He recalled the press conference at the SPS Fair in 2018, when this initiative was agreed upon between the top 3 automation suppliers and many other companies specialized in certain areas in automation, but also with IT companies.  Since then, the number of 23 companies forming the steering committee has expanded to 27 companies as of today.

Peter Lutz made it clear that OPC UA is not a communication protocol, but an industrial framework enabling secured, standardized data and interfaces for industrial communication.  The main pillars of OPC UA are Interoperability, Data Modelling, and Security.  OPC UA based communication not only reaches out into the machinery and process devices but upwards also to enterprise IT systems.

For the field level communication, the use cases are controller to controller, controller to device, device to device, controller to compute, device to compute, and compute to compute.  With compute being, for example, gateway, software or clouds.

The FLC working groups are currently specifying the controller-to-controller communication, and after this, controller to field device communication will be specified.  It can be expected that controller to controller specifications can be implemented into products within 2021, but the controller to field device communication specifications may not be available before the end of 2022.  Certainly, it must be acknowledged that the current COVID-19 pandemic has, to a certain degree, slowed down the work of the over 300 technical experts from more than 60 member companies.

Takeaway for ARC: it will take a lot of effort before OPC UA over TSN can play out its advantages in the field level, especially with multi-axis servo motion control applications.  But the consensus across the large number of supporting members is to achieve open, non-proprietary communication means across different brands and devices, based upon international standards.