Last fall, some of the biggest industrial network news of the year was announced at the SPS/IPC/Drives show in Nuremberg, Germany. As highlighted in my article summarizing those announcements, one of the key developments at the event was OPC UA's initiative to include time-sensitive networking (TSN) down to the field level.
Most notable was the OPC Foundation’s plan for using the publish/subscribe (PubSub) method of communication—rather than the client/server method—for controller-to-controller and field-level communications as part of this initiative.
In the ARC Advisory Group paper, “How OPC UA and TSN Are Driving the Creation of a Universal Industrial Network,” analyst David W. Humphrey notes that the OPC Foundation initially refrained from actively promoting PubSub to the field level. "In response, a group of about 15 automation suppliers, led by the companies B&R and TTTech, formed an initiative in 2016 called the Shaper Group," he writes. "The Shapers lobbied actively for the rapid development of ‘an open, unified, standards-based IIoT communication solution between sensors, actuators, controllers and cloud addressing all requirements of industrial automation,’ with OPC UA and TSN as the basis. In 2018, Rockwell Automation joined the group, bringing with it the weight of its market might in North America.”
Humphrey contends that the OPC Foundation’s commitment to and promotion of OPC UA over TSN using PubSub as an alternative to classic master-slave I/O communications protocols “removed any doubts about the future of a universal Ethernet-based industrial network.”
With this development, however, the "onus is now on automation suppliers to implement OPC UA over TSN in field devices, promote its advantages, and provide a clear migration path for users,” Humphrey says.
Of course, even with this groundwork in place, nothing about industrial networks will change overnight. Humphrey notes that "the inertia of the installed base of industrial Ethernet devices is high, so transition to a new universal industrial network will be a slow process. Realistically, it will likely take many years, maybe even a generation, before the current variety of Ethernet-based industrial networks fades away.”
In the interim, much work remains to be done—and specific tasks will fall to automation suppliers, machine builders, and process equipment suppliers.
For automation suppliers, Humphrey recommends that they begin educating their customers on the need for and the advantages of a universal industrial network. Though this may seem to be a tall order, it’s worth noting that more than 20 major technology suppliers currently count themselves among the committed contributors to the "OPC UA including TSN down to the field level” initiative. (For a list, see the “2019: The Year of the Industrial Network Protocol” article)
Humphrey recommends that machine builders and process equipment suppliers join OPC Foundation working groups to create companion specifications rather than leaving this up to automation suppliers. He notes that several companies, including manufacturers of robots, machine tools and injection molding machines have already taken this step in order to have a voice in the process.