Volker Goller, Systems Applications Engineer in the Deterministic Ethernet Technology Group at Analog Devices, explains the background.

What features predestine OPC UA and TSN for Industrial Communication 4.0?

Goller: OPC UA is first and foremost an information model. Of course, there is also a protocol for connecting clients and servers, but the strength of OPC UA is the address space, which makes it a universal application interface. The flexibility of OPC UA allows existing user interfaces - the "profiles" of the Industrial Ethernet protocols - to be mapped in OPC UA. For this reason, there is now a mapping to the OPC UA address space for almost every profile of an Industrial Ethernet protocol, or work is underway on such a mapping. OPC UA itself does not yet specify such profiles - 'IO', 'Drive', 'Safety', etc. - but this is likely to change. In the context of Industry 4.0, OPC UA is seen as a 'lingua franca', with correspondingly great potential for the future.

TSN, on the other hand, is an extension of IEEE 802.3 Ethernet with a whole range of new possibilities with the aim of making Ethernet more deterministic and real-time capable. Because TSN-capable hardware is expected from many manufacturers in the future, it can be seen as a democratization of real-time communication. Almost any protocol could be given real-time properties with TSN.

What are the concrete benefits of combining the two technologies?

Goller: The OPC Foundation's Pub/Sub working group is specifying a real-time-capable transport protocol for OPC UA based on a publisher/subscriber model for linking with TSN. This makes OPC UA real-time-capable and potentially an alternative to Industrial Ethernet protocols. It would therefore be very welcome for the level above the classic PLC, as controllers from different manufacturers could interact with OPC UA in real time. TSN can also give OPC UA a guaranteed bandwidth in the network and therefore greater robustness than is currently possible.

What tasks will remain for traditional Industrial Ethernet systems and fieldbuses in the future?

Goller: The classic Industrial Ethernet protocols will not disappear. Some will continue to exist in a different form (as profiles or profile families in OPC UA), others will themselves be based on TSN in the future. Fieldbuses will be replaced by Ethernet.

What tasks could the classic industrial Ethernet systems fulfill in OPC UA TSN systems at the profile level?

Goller: To be very clear once again: TSN does not automatically require OPC UA. They are two completely independent technologies. OPC UA can play a major role in the networking of controllers (controller to controller). In this area, Pub/Sub with TSN is advantageous. Whether it can also play a role at field level remains to be seen. OPC UA is not a 'small stack', at least not if you want to take advantage of all the benefits.

To what extent does the desire to implement transmission rates of 1 GBit/s and higher play a role in TSN?

Goller: 1 GBit/s (and beyond) is a logical further development of today's networking. Will it replace 100 MBit/s? Not everywhere, but 1 GBit/s will enable new applications and overcome today's performance bottlenecks in data-intensive applications.