Ethernet Solutions Evolve and Gain Ground on Fieldbus

For decades now, Ethernet solutions have been gaining ground (in terms of both their absolute number of users and their percentage of all industrial nodes) on legacy fieldbuses as the automation industry increasingly takes advantage of Ethernet’s superior bandwidth, cost-effectiveness, and general familiarity. While it was once nondeterministic and incapable of being reliably used in control systems, Ethernet has since evolved and been incorporated into many protocols, such as PROFINET®, EtherNet/IP®, Ethernet Powerlink, and EtherCAT®, that can handle even highly demanding applications such as motion control.

In the long run, industrial Ethernet appears set to transform further into the underlying network that supports time sensitive networking (TSN). TSN is basically a set of extensions to the IEEE 802.1 and 802.3 standards, with roots in the audio video bridging project, which was originally designed for the deterministic synchronization of professional audio and video streams. The ideal of TSN is to create something that is:

  • An open, interoperable standard that can be used by vendors around the world
  • Able to provide immunity to critical traffic from lower priority converged traffic1
  • Easy to use, provisioned, and incorporated into existing network infrastructures
  • Economical with the ability to converge multiple types of traffic onto the same wire
  • Real-time, thanks to low jitter guaranteed latency and zero congestion for critical control loops

There have been a lot of important TSN-related developments in recent years, including the launch of the world’s first TSN testbed by Bosch Rexroth, Schneider Electric, Cisco, TTTech, National Instruments, and Kuka in February 2016.2 While manufacturers, automakers, and others await and contribute to TSN, other forms of industrial Ethernet continue to thrive, indicating that we can expect further movement away from, if not total abandonment of, fieldbuses in the years ahead.

With TSN on the Horizon, Sales of Industrial Ethernet Solutions Continue to Rise

Fieldbus had an enormous head start on Ethernet, which only became a viable alternative in the last 15 years or so. It is also important to remember that the change from 4 mA to 20 mA to fieldbus was a much more significant upgrade than the later shift from fieldbus to Ethernet. With 4 mA to 20 mA, analog signals had to be run over many different wires with a single scalar value. In contrast, with fieldbus, consolidation into a digital network with actual values and status information finally became possible.

Ethernet is a digital network like fieldbus. Still, its improvements over fieldbus are substantial. As the Industrial Internet of Things (or Industry 4.0) comes into focus, Ethernet will only become more important due to its easier scalability and greater bandwidth compared to fieldbus. It also allows many dedicated networks and pieces of infrastructure to be consolidated into a more cost-effective automation platform.

“Industrial Ethernet is about creating an automation network; the difference is that industrial Ethernet expands the network beyond the realm of control engineers,” Michael Bowne, director of technology marketing for PI North America, explained in an article for Automation World.3 “To better understand this difference, consider safety applications. In the past, a separate, dedicated safety system of contactors and relays was required in addition to the existing automation network. Today, all those contactors can be connected to industrial Ethernet, thereby eliminating the extra wiring. Users can also replace many relays with a safety logic controller.”

These types of benefits have helped boost the market share of PROFINET (which Bowne focused on in his piece), as well as EtherNet/IP and others. A February 2016 report found that all Ethernet protocols accounted for about 38% of all installed nodes, while fieldbus totaled around 58% (the remaining 4% was wireless such as Bluetooth and Wi-Fi, which were surveyed for the first time this year).4 While the gap between the two is undoubtedly wide, it has actually closed since 2015, when the fieldbus market was still twice the size of its Ethernet counterpart.

The breakdown of individual protocols revealed that:

  • PROFIBUS was again the overall leader, representing approximately 17% of nodes across the board
  • Among Ethernet solutions, EtherNet/IP was the worldwide leader at 9%, barely edging out PROFINET at 8% and “other Ethernet,” also at 8%
  • Fieldbuses as a whole exhibited a 7% growth rate between 2015 and 2016; meanwhile, Ethernet solutions surged 20%
  • The Ethernet growth rate is impressive since it actually increased compared to 2015 (20% vs. 17%), despite having a larger overall number of nodes this year than last one
  • Protocol adoption varied a lot by region; for example, in Europe and the Middle East, PROFIBUS occupied the top spot, while PROFINET was the fastest growing 
  • However, common industrial protocol networks ruled the roost in the U.S., with EtherNet/IP and DeviceNet both near the top of the list there
  • In Asia, there was no clear leader, only the usual suspects, including PROFINET, EtherNet/IP, Modbus®, and CC-Link
  • Looking ahead, the IIoT could be a big driver for uptake of both Ethernet and wireless technologies

Looking at What Is Ahead for the Industrial Ethernet Market

Although industrial Ethernet has been around for a while, only in the last few years has it really made inroads into factories and other settings. The previous results demonstrate that it still has a lot of headroom for growth, too.

Through 2019, industrial Ethernet sales are expected to climb at an average rate of around 9.5%, according to numbers from Technavio.5 Factors driving this trend include the relative ease of adopting Ethernet (which is now a familiar office technology) and the ability to move larger amounts of data at higher speeds than would ever be possible with fieldbus.

The Evolution of Ethernet Equipment

One thing to watch for the rest of this decade (in addition to developments pertaining to TSN) is how Ethernet equipment will evolve for new use cases and environments across the IIoT. For instance, when Ethernet first entered factories, the RJ45 connector—already ubiquitous on consumer electronics such as PCs as well as data center equipment like network switches—was the most popular Ethernet cordset. RJ45 is only one type of Ethernet connector.

It remains so in the overall Ethernet market, but in many plants RJ45 has been superseded by the M12 connector, which offers more robust protections from the vibrations, shocks, and other pressures common in industrial environments. With the IIoT and TSN now on the radar, we may see a shift away from M12 to M8 in order to use tinier I/O modules and accommodate even smaller devices.

M8 supports high data transfer rates (up to 100 Mbps) and also provides ingress protection, which makes it ideal for a wide range of industrial applications. In addition to the updates to connector types, there may also be a shift in cabling, especially as category 8 cables becomes standardized by the Telecommunications Infrastructure Association.

Ethernet and Hazardous Settings

Ethernet has many possible areas to expand into in the coming years. One promising sector involves hazardous industrial environments, in which legacy fieldbuses have long had a leg up. PROFIBUS and others are still mainstays in such settings but the potential of industrial Ethernet will make it increasingly hard to pass up.

“Another area of expansion will be in Ethernet for hazardous locations, where PROFIBUS, Foundation Fieldbus, and AS-I currently lead the pack,” Laura Schweitz, connectivity product manager at Turck, explained in an article for Machine Design. “This trend is emerging as engineers and system integrators look to gain the faster speeds and advanced connectivity other industries are already enjoying with Ethernet.”

These use cases and others show why industrial Ethernet has a sunny growth outlook. It may still trail fieldbus worldwide, but the gap should continue to close thanks to increasing use of today’s industrial Ethernet protocols in addition to the gradual rollout of the standardized TSN.


1 George A. Ditzel III. “Time Sensitive Network (TSN) Protocols and Use in EtherNet/IP Systems.” OVDA Industry Conference, 2015.

2 “NI, Bosch Rexroth, Cisco, Intel, KUKA, Schneider Electric, and TTTech Announce Collaboration on Time Sensitive Networking Testbed With the Industrial Internet Consortium.” National Instruments, 2016.

3 Michael Bowne. “The Continuing, Critical Role of Industrial Ethernet.” Automation World, 2016.

4 Rechelle Tangcangco. “HMS Estimates Industrial Network Market Shares in 2016.” Control Engineering, 2016.

5 Laure Schweitz. “Ethernet Connectors Evolve to Meet New Demands.” Machine Design, 2016.