Ever since the “fieldbus wars” of the 1990s, automation standards proponents have lamented that industry could not agree on a universal industrial network standard. The good news is that it’s finally coming, and this article explains how it can be part of your company’s strategy.
This article is part of our monthly Automation Zone column. Read more from our monthly Automation Zone series.
OPC UA (Open Platform Communications Unified Architecture) over TSN (Time Sensitive Networking) combines IEEE 802.1 standards for deterministic network performance with communications functionalities being developed by the OPC Foundation’s Field Level Communications (FLC) initiative. When the standards come together later this year, there will finally be a single, interoperable industrial Ethernet supported by the major automation technology providers.
This is important because while the legacy fieldbuses are also adopting TSN technology to improve performance, without the OPC FLC functionalities, those existing networks will still not be interoperable, a capability that is especially critical for the converged networks enabling IIoT. Fieldbuses over TSN also will not benefit from OPC UA capabilities such as built-in cybersecurity, semantics, and a number of companion specifications.
It is not anticipated that MRO teams will need to replace existing networks with OPC UA over TSN unless there is a specific requirement (i.e., if it ain’t broke, don’t fix it). However, now is the time to consider OPC UA over TSN for any of the following: new projects in the plant; IIoT communications; and adding functionalities such as machine to machine (M2M) communications in order to synchronize production lines that often have no or only rudimentary coordination.
Here’s what’s happening now.
Open Source Automation Development Lab
The Open Source Automation Development Lab (OSADL) is embarking on its third phase of funding and functionality development for OPC UA over TSN. The organization has already developed a publisher/subscriber (pub/sub) communications stack that is certified, lightweight, secure, and stable. They’ve also developed a TSN driver. This pub/sub provides faster network performance compared to client/server architectures. Further information can be found at the following link: https://www.osadl.org/OPC-UA-over-TSN.opcua-tsn.0.html
The OSADL project complements the work of the OPC Foundation’s FLC initiative. OPC Foundation is defining a fieldbus standard, with, for example, an information model for bus couplers or motion drives with basic states in common and with connection management. The OSADL project also is one layer below FLC, providing basic functionality for OPC UA to be able to communicate in real-time with third party devices. Overall, OSADL is defining how information is transported, while OPC Foundation is defining what kind of information will be exchanged.
The same is true for TSN, so a Linux system can have drivers for TSN optimized in terms of performance and quality, and can be configured as a TSN device with a common communication interface that hardware and component vendors can build upon and provide chip level hardware drivers that talk to the chip in the most efficient way.
What should we expect in 2020?
OPC UA is all about the combination of interoperability and performance. Performance includes the determinism of TSN with the interoperability, semantics, cybersecurity, and performance of OPC UA with the pub/sub. Early adopters across the spectrum of automation technology providers, machine builders, systems integrators, and industrial machinery users will benefit if they value these attributes. Applications include discrete, batch, and continuous process control; connectivity within and between machines; and IIoT communications between devices, edge controllers, and fog and cloud systems.
Virtually all industrial device manufacturers would appreciate getting beyond the cost of supporting multiple fieldbuses, whether they are adopting TSN or not. And I suspect most IT people cannot understand why OT has “flavors” of Ethernet that are not natively interoperable. We are seeing interest among end users who want to mix control platforms on their production lines to achieve best-of-breed performance. For integrators and machine builders, OPC UA over TSN means more flexibility and an alternative to supporting multiple fieldbuses.
Users pursuing a digital business strategy across the enterprise will find that OPC UA over TSN acts as the glue that binds manufacturing and logistics systems behind the scenes, with their first mover advantages in e-commerce, mass customization, direct-to-consumer, and related initiatives.
We are already seeing control hardware that could be termed “OPC UA over TSN ready,” including switches, PLCs, and industrial PCs. These early product introductions mean that systems purchased today can provide a smooth transition from the current to future networks without replacing hardware.
Software development suites supporting OPC UA over TSN are expected in fourth quarter 2020. Expect simple, automatic configuration of OPC UA over TSN networks for real-time communications, data exchange, traffic classes, routing, and scheduling.
For controller to controller (i.e., third-party controller) communications, expect it to be a simple matter of configuring the address to which to publish and what variables to publish. To subscribe from a third-party device, expect to simply import the information model from the third-party controller and the variables to subscribe to, and then write the subscribed value to the internal variable in the controller.
As companies increasingly implement digital business strategies to make the enterprise more adaptive to changing marketplace requirements, increased networking requirements are inevitable. Now is the time to get ahead of the game, before decisions are made without your input that could impact plant systems and possibly disrupt operations:
- Familiarize yourself with the differences between OPC UA over TSN and fieldbuses over TSN, as there is some confusion in the marketplace, and determine which approach best serves your objectives.
- Make sure you have a place at the table on the “OT/IT” team, teams that are currently being formed for the most part from controls engineering and manufacturing IT.
- Challenge status quo thinking – red flags include arguments to avoid capital investment, the learning curve of new technologies, and even the cost of new spares inventory – to prevent necessary technology advances from being postponed in your facility while your competitors gain the advantage.