What's next for industrial Ethernet?

Plant Engineering spoke with Brian Oulton, an ODVA contributor and participant on behalf of Rockwell Automation, a principal member of ODVA to learn how Ethernet and EtherNet/IP are contributing to networking success on the plant floor.

07/28/2010


Ethernet has come a long way since its appearance in the early 1980s. The personal computer industry learned how to make the basic technology affordable. Automation vendors working toward a single network architecture have learned how to enhance its performance to become a robust networking solution for the plant floor. In order to get suppliers and users moving in the same direction, there needs to be standards. ODVA is a standards organization that manages the development of open technologies, and assists manufacturers through its activities in standards development, certification, vendor education and industry awareness.

 Plant Engineering spoke with Brian Oulton, an ODVA contributor and participant on behalf of Rockwell Automation, a principal member of ODVA to learn how Ethernet and EtherNet/IP are contributing to networking success on the plant floor.

PE: What factors are responsible for sharp increases in the adoption of Ethernet (in all its forms) for industrial networking on the plant floor in recent years?

Oulton: Ethernet has been very popular for many years as a programming and HMI network in industrial automation because of its speed and ability to handle large amounts of data such as the download of a programmable controller program. As the technology moved from 10 M and hubs to 100 M and switches, vendors added many more automation products and expanded Ethernet’s usage to include most, if not all, of the space occupied by traditional fieldbuses. Customers are adopting Ethernet rapidly because it has now been proven to work well, handle a variety of applications and is relatively well known because of its use in the business enterprise.

PE: Among the variations of Ethernet used in industrial applications, EtherNet/IP seems to be ranked second, only to native TCP/IP. Why has EtherNet/IP outpaced other “versions” of Ethernet?

Oulton: EtherNet/IP is the world’s leading industrial Ethernet network for a number of reasons. First, it is capable of handling the widest range of applications including discrete, safety, motion, process and drive applications. Several Ethernet derivatives are limited to niche applications – either by design or by the narrow range of products that are currently available on the network.

Second, unlike some Ethernet-based networks, EtherNet/IP uses the same standards that are used for e-mail, the Internet and many other popular applications in the very same way as those applications – without modification. This enabled vendors to adopt EtherNet/IP quickly, and provided many features and tools that already existed to be applied directly to industrial networking. Others moved slowly because their modifications to standards prevented reuse of these features and tools; instead they had to develop from scratch.

Third, the EtherNet/IP standard is managed by ODVA, a fully open organization with balanced membership of vendors contributing to the standards work and services provided to help other members. As a result, EtherNet/IP delivers interoperable Ethernet products from a large community of vendors, thus solidifying EtherNet/IP as the network of choice. Today, more than 250 vendors – including Rockwell Automation, Schneider Electric, Omron, Emerson, Mitsubishi and other leading automation vendors have recognized the advantages of EtherNet/IP and are supplying OEMs and end users with more than 850 automation product lines and several million installed devices on EtherNet/IP.

PE: The actual definition of Ethernet refers to the data transmission cabling system, and occupies only the bottom two layers in the ISO protocol stack. Briefly explain the protocol stack and how the other layers make Ethernet more usable in industrial networking applications.

Oulton: When you hear about standard IEEE 802.3, it refers to the physical layer of the ISO/OSI Reference Model. The popular standard for the middle layers of Ethernet are referred to as TCP/IP or TCP/UDP/IP. Novell Netware and several other network protocols pale in comparison to the popularity of TCP/UDP/IP. The top layers contain the actual application protocols for e-mail, the Internet and many other applications including the Common Industrial Protocol that powers EtherNet/IP when used on this stack; and ControlNet, DeviceNet and CompoNet when used with other stacks. Using the bottom (physical) layers of Ethernet enables the industrial Ethernet to use the same hardware and chipsets made available in the Enterprise and elsewhere, but using TCP/UDP/IP enables the use of many standard tools and features such as the ability to prioritize some traffic over others.

PE: EtherNet/IP is now making its way to instruments and other device-level automation system components. What are some examples of the types of devices that can now make use of EtherNet/IP connectivity?

Oulton: There is an array of EtherNet/IP products currently available and operating in manufacturing facilities around the globe. The catalog is extensive and spans a wide range of control-system requirements. Well beyond HMI, controllers, robots, I/O, valves, drives and computers, EtherNet/IP today supports torque tools, welders, barcode, vision systems, weighing instruments and countless others.

Among the latest examples are devices used in precision motion control systems. The Allen-Bradley Kinetix 6500 servo drive from Rockwell automation uses CIP Motion, an extension of the Common Industrial Protocol (CIP) from ODVA. CIP Motion technology combines the requirements of deterministic, real-time, closed-loop motion control, offering full compliance with Ethernet standards including IEEE 802.3 and TCP/IP. Position, speed and torque loops can be set within the new Kinetix 6500 servo drive, delivering an open, high-bandwidth solution for motion control. Add the power of ODVA’s CIP Sync technology – the IEEE-1588 compliant Precision Clock Synchronization – and multiple axes can be coordinated for precise, synchronized motion control.

In the instrumentation market, Endress+Hauser recently announced the launch of its Promass 83 Coriolis Mass Flow Meter with EtherNet/IP connectivity. This instrument joins an array of EtherNet/IP-enabled products that provide significantly more information than when on conventional process instrument networks, joining several high-end analytic instruments and other devices used in process applications.

PE: Some versions of Ethernet bypass the TCP/IP stack. Why do some “standards” choose to bypass it? Why does EtherNet/IP include TCP/IP?

Oulton: Some networks use standard Ethernet but don’t comply with TCP/UDP/IP because they were developed before the potential of TCP/IP was fully understood. While these networks may use standard Ethernet cable, you’ll need to use special, proprietary switches, and you may not be able to use the standard network management or troubleshooting tools that your IT people use on your business system. You’ll likely need special training and services to make these networks work. Further, completely standard devices inserted into the middle of these networks can cause problems for the entire network.

Fortunately, ODVA had the innovation and foresight to understand that standard Ethernet technology was advancing quickly enough in the right direction to be able to support industrial purposes without modification. As a result, EtherNet/IP is in a better position to take advantage of new developments than those networks that modify hardware or bypass the TCP/IP stack.

PE: What major changes in industrial Ethernet, in general, and EtherNet/IP specifically are coming in the near future? 2010 and beyond?

Oulton: The use of standard wireless Ethernet (IEEE 802.11N) is going to become much more significant in industrial networking. The latest standard added many things needed to provide the stability required for industrial applications. Also, there will be a lot more innovation and improvements around physical media and cabling and different ways of transmitting the Ethernet signals – whether that’s media that work well in hazardous or explosive areas or media that carry both power and signal. These technologies will be refined and will allow for easier deployment and more flexibility in how to get those signals from point A to point B.

We also expect additional refinements that will help make the user experience even better with EtherNet/IP. Unlike fieldbus where a lot of work is required to create good diagnostics and tools, with EtherNet/IP, there’s already a wealth of tools, skills and features that are available. Future enhancements will help expand these capabilities and improve the network’s performance in the industrial space.

The other area involves leveraging technology advancements and innovations in the commercial sector, whether it’s cell phones, PDAs or digital cameras. Many of these operate with standard Ethernet and standard IP, which makes them easy to apply for industrial use.

 

PE: What’s the single biggest factor a plant engineer or control engineer should consider when looking at implementing Ethernet (or any other type of communication) in an industrial manufacturing environment?

Oulton: The application of EtherNet/IP can do incredible things to support and accelerate network convergence that can provide business agility and innovations that were previously impractical. To get started, check out the resources at www.ab.com/networks/architectures.html, which provides education, design guidance, recommendations and best practices for implementing Ethernet in an industrial manufacturing environment. These resources address topics relevant to both engineering and IT professionals.

 



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