Not So Fast: TSN Not Quite Ready for Prime Time

Though standardization efforts for Time-Sensitive Networking continue at pace, it is still years before industry should expect to see a bumper crop of compatible products.

Time-Sensitive Networking (TSN), widely touted as a revolutionary advancement of industrial Ethernet, promises to usher in reliability and deterministic capabilities critical to progressing the Industry 4.0 agenda. However, the highly anticipated collection of standards—part of a push for a unified foundation for industrial networking—is still not ready for prime time. The bulk of activity around TSN remains concentrated on standards setting rather than full-throttled product development.

Industrial Ethernet continues to gain traction in the automation and manufacturing space, driven by the need for high-performance integration between the factory and Industrial Internet of Things (IIoT) systems along with information/operations technology (IT/OT) convergence. A study by HMS Industrial Networks shows industrial Ethernet with an annual growth rate of 22 percent and a dominant 52 percent share of the global market compared with fieldbuses at 42 percent.

Though industrial communications devices based on industrial Ethernet protocols such as EtherNet/IP, Profinet, and EtherCAT deliver some level of determinism, there are limitations and, more significantly, interoperability issues impeding the vision for a single, open network that links the plant floor with the greater enterprise. Enter TSN, viewed as a way to achieve the requisite levels of determinism and security for new Industry 4.0 applications while also integrating industrial control, IT, video and other communications.

“Each industrial Ethernet technology can’t share a single Ethernet network without gateways or without compromising the performance of each,” says Atsushi Sato, an industrial network specialist for Yokogawa Electric. TSN, with its extensions on IEEE 802 Bridge and Ethernet standards related to timing and synchronization, deterministic data transmission, reliability, and configuration, is designed to solve those problems. “With those extensions, Ethernet is no longer a `best effort’ network, but instead has native real-time and reliability features.”

 

Setting standards is a march, not a race

The TSN Task Group, part of the IEEE 802.1 Working Group, has been hammering out a set of standards for deterministic services through standard Ethernet networks to ensure guaranteed packet transport with bounded latency, low packet delay variation, and low packet loss. In laymen’s terms, that means the evolving network standard is designed to ensure the reliable delivery of mission-critical, time-sensitive network traffic using built-in management and security capabilities that can prioritize the low-latency communication required for fast system response and closed-loop control applications.

Though TSN has its roots in the audio-visual industry, the evolving standard lends itself to a range of time-sensitive industrial use cases. For example, applications requiring very high communication bandwidths such as semiconductor and electronics manufacturing are prime candidates as are other environments that employ video streaming with high resolution for accurate parts inspection or remote operator control of safety and hazardous locations, notes Al Beydoun, president of ODVA, an association of companies focused on advancing open, interoperable information and communication technologies in industrial automation. Motion control and robotics applications requiring precision timing control could also benefit from TSN, and the automotive industry is moving in that direction to provide higher bandwidth in support of infotainment, connectivity, and driver assistance vehicle features, he says.

TSN will also help facilitate many Industry 4.0 applications, which are dependent on real-time IIoT data along with data from previously siloed automation systems. “If you want data, you need an easy way to access it, which means you need to connect every isolated network together,” explains Jack Lin, product manager for Moxa. “TSN helps you connect all systems data in one unified network without sacrificing reliability and determinism, which you can only achieve today with isolating networks.”

In addition to the IEEE standards-setting process, organizational alliances are doing their part to advance the standard. One example is a partnership between the Industrial Internet Consortium (IIC) and Avnu Alliance, which is working to advance development and interoperability of devices built on TSN open standards via TSN testbeds and exchange of best practices. Many of the industrial Ethernet protocol groups—for example, the EtherCAT Technology Group (ETG)—are also coordinating with the IEEE committee to ensure their offerings can support TSN upon release of the standards set, expected to be finalized by 2020. In addition to those efforts, there is the IEC/IEEE 60802 industrial profile for TSN, targeted for a mid-2021 release, which is designed to promote interoperability through the specification of TSN profiles for industrial automation. The latter is important because, if a product ignores the profile and provides non-compliant TSN features, it will lose interoperability, experts say.

“TSN is not viable yet—it’s all concept-based right now—so we don’t have products yet,” notes Sree Potluri, I/O product specialist at Beckhoff Automation. “If a customer wants to use it as part of a networking mix, we will be ready and accommodate it.”

At the same time, Beckhoff is planning ahead: The company is actively working with the IEEE standards bodies and has released the EK1000 EtherCAT TSN Coupler, which will bridge EtherCAT and TSN networks. Beckhoff also announced the new EtherCAT G gigabit communication technology to push EtherCAT performance to the next level by delivering Gigabit Ethernet speeds to support highly data-intensive applications.

Belden has a number of products that are TSN-ready, which will be updated with firmware when the specifications are finalized, according to Stephan Kehrer, senior architect in Belden’s CTO office. For example, the company’s RSPE35 and RSPE37 switches, out in the field for some time, have received a software update that will enable TSN features, he explains. Moreover, the Hirschmann Bobcat compact managed switch is Belden’s first appliance to provide advanced security and real-time communication through support for TSN on all ports in an effort to standardize Ethernet usage.

 

Prepping for TSN’s arrival

As the standards efforts wind down and vendor activity picks up, manufacturers can be doing a number of things to prepare for the gradual transition. Ensuring any new industrial network is built on a variation of Ethernet that supports multiple protocols on the same wire is critical, as is cultivating internal expertise in the more complex software configuration necessary for implementing real-time applications.

At the same time, vendors insist efforts are underway to ensure there will be a seamless transition. For example, PI North America, a member-supported trade organization that advances and educates users on Profibus and Profinet, maintains that companies making an investment in Profinet devices will be able to migrate to TSN devices when they are ready. The organization plans a June release of a specification for Profinet on TSN, which will eventually unleash a wave of TSN-enabled products.

“If you picked Profinet today, there is nothing to do—the same engineering and configuration of the network will look the same,” says Michael Bowne, executive director of PI North America. “But behind the scenes it will run more smoothly because of TSN.”

Phoenix Contact, which makes industrial routers, switches, and controllers, plans to hold off promoting any TSN-ready offerings until the official standards are ratified, which puts it closer to the 2020 timeframe. The reason, says Ken Austin, the company’s senior product marketing specialist, is to avoid having to retrofit or do hardware or software changes based on what the IEEE committees actually do.

“What is the purpose of being TSN-ready if they make an about-face and make changes to the standard and then your product is no longer TSN-ready?” he asks. “We plan to hold pace until the ratification of the standard and then develop products from there.”

Ultimately, it will be users who dictate the pace of TSN’s market penetration. Judging from traditional technology adoption in the automation sector, experts expect that the deployment curve will be inevitably slow. “The way the industrial automation sector moves, you usually have 15-year-plus lifecycles,” Belden’s Kehrer notes. “If you have an installation in the field now, you probably won’t just replace it with TSN networks. When new machines are designed, new plants set up, or network segments modernized, that’s when we’ll see more TSN technology come into place. It will be five to 10 years at least until we see TSN spread very widely.”

>> Read an FAQ on OPC UA over TSN.


SIDEBAR: Wireless Mesh Reality Check 

Another advanced networking technology slowly making its way to market is wireless mesh, a capability that lends itself to Industrial Internet of Things (IIoT) applications because of its ability to handle a huge number of devices that generate sporadic transmissions of short packets.

Though traditional wireless networks are increasingly being deployed in industrial environments to accommodate rotating equipment or areas that are remote or difficult to reach by cable, they have limitations that worsen in the advent of increasing machine-to-machine (M2M) connectivity traffic. A new technology known as kinetic mesh is being touted as better suited for IIoT scenarios because all nodes are equal in configuration, allowing for communication on a peer-to-peer basis.

Kinetic mesh is also full duplex, which allows a single node to receive data on one frequency and simultaneously send it out on another frequency, creating high speeds and resulting in extremely low latency, experts say. A kinetic mesh network also dynamically selects the fastest path out of hundreds of options to automatically circumvent interference or signal blockage, which makes for consistent, reliable connectivity via a variety of options.

At this time, however, there are few wireless mesh solutions primed for the industrial space, according to Nick Sandoval, product marketing manager at Moxa, which is planning to release its first industrial mesh product based on the Wi-Fi standard next year.

The reason for the lack of industrial wireless mesh offerings is that the standards are higher than what’s required for commercial products, Sandoval says. Specifically, there is a perception that wireless reliability is not as robust as traditional hardwired networks and there are also security concerns surrounding Wi-Fi. “For industrial systems, availability is everything—you can’t have any downtime,” he says.

There’s also the matter of domain expertise required for wireless and, especially, the new mesh technologies. “It’s a different skill set—you have to understand channels and frequencies, things you don’t have to deal with with wired networks,” Sandoval says.

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