Many industrial networks solutions built on IEEE 802.x Ethernet standards are available to vendors and end users. Even as vanilla Ethernet evolves with the support of organizations such as the Ethernet Alliance, many Ethernet-based standards—or more accurately, Ethernet-based industrial networking protocols—have emerged. They help developers use commercial IT economies of scale, and future-proof networks as Industrie 4.0 and the Industrial Internet of Things (IIoT) redefine smart manufacturing across industry lines.
Industrial Ethernet solutions serve diverse needs, and speeds, which typically range from 10 Mbit/s (megabits per second) to 1 gigabit per second (a.k.a. Gigabit Ethernet), while 100 Mbit/s is the most common speed for communicating control data from field to host devices.
Some solutions are tailored to process applications, while others are best known in the discrete world. Generally, it’s not the technology, but market factors that give each solution its momentum. The key is vendor support, says Harry Forbes, research director with ARC Advisory Group. “If the solution is widely used in the end user’s vertical industry, and it's also an important part of their vendors’ offering, then they're much more likely to adopt it," explains Forbes. "They don’t want to be the only plant in their industry or region that's running their process with a particular platform.”
As a result, process industry professionals would do well to become familiar with developments from several industrial Ethernet consortia, including those that cross industry lines.
HART-IP, Foundation Fieldbus HSE
As the digital transformation of IIoT and Industrie 4.0 emerges, “End users are increasingly interested in gathering diagnostic data from their HART instruments," says Paul Sereiko, marketing director, FieldComm Group, which administers the HART and Foundation Fieldbus protocols. "HART-IP multiplexers, RTUs and WirelessHART gateways provide a simple, easy way to capture this information.”
The most recent Ethernet-enabled developments at FieldComm Group include HART-Internet protocol (IP). Similar to the hybrid analog-digital HART communication protocol, HART-IP communicates between intelligent field instruments and host systems, such as DCSs, asset management, safety and SCADA systems, and mobile devices from laptops to handheld configurators. The application layer for HART-IP is the same for all HART protocol-enabled field devices, but employs Ethernet physical media and a standard TCP/IP protocol in a solution with speeds from 10 Mbit/s to 1 Gbit/s. Therefore, it eliminates the time and errors of data mapping, for example with Modbus RTU, and simplifies setup and using a backhaul network for WirelessHART gateways, wired HART multiplexers and remote I/O. Security continues to evolve for HART-IP (Figure 1).
Meanwhile, for Foundation Fieldbus users, Foundation Fieldbus High-Speed Ethernet (HSE) specification has been available since the early 2000s, is standardized as IEC 61158, and uses Ethernet to connect plant communications from fieldbus to higher-level devices such as controllers and remote I/O using a 100 Mbit/s solution tailored for process plants.
In addition, FieldComm serves as clearinghouse for Field Device Integration (FDI), which allows integrating competing electronic device description language (EDDL) and field device tool (FDT) device data standards into one platform for greater interoperability, adding value to higher-level Ethernet solutions.
Profinet proves pervasive
Mike Bowne, executive director of PI North America, says more than 3 million Profinet devices went to market in 2015—a 30% increase over the previous year. “And 2016 is on pace to beat that again,” he adds. The latest news is that a new, intrinsically safe (IS) version of PI's Profinet industrial Ethernet protocol is being developed that will be based on Advanced Physical Layer (APL) technology. It will employ a two-wire connection with limited current/voltage to be IS, while still providing power and segments longer than Ethernet’s present, 100-meter wired limit (Figure 2).
In related news, work on Profinet includes Process Application (PA) Profile 3.02, which eases replacement of aging instruments by eliminating reconfiguration of the DCS or device by automatically assuming the parameters of the (older) device they’re replacing. A pending PA Profile 4.0 will be released in the near future, Bowne adds, “with further developments for process control users.”
Profinet can connect to devices, controllers, I/O and field devices, the latter through the use of proxies to access data from IS fieldbuses such as Profibus PA. “In these hazardous environments, Profibus PA cables can land directly on an instrument; Ethernet cables can't—yet,” explains Bowne. This is partly due to PI North America’s support of FDI technology.
While work continues to bring Ethernet-based solutions to the field, Bowne says inexpensive sensors and actuators without a Profinet interface can employ the point-to-point communication IO-Link standard (IEC 61131-9), which uses the same, common, three-wire cable that many sensors already use.