Ethernet protocol selection, other implementation answers
Certain consideration up front will help optimize your next industrial Ethernet implementation, according to Brian Oulton, director, networks business, Rockwell Automation. Questions and answers follow.
Why was Ethernet chosen instead of another industrial network?
To achieve true business agility, machine builders and manufacturers need a simple network architecture that can connect across applications and from the IT infrastructure to the instrumentation level in order to access real-time production data. By far the most popular is Ethernet.
Ethernet has been very popular for many years as a programming and human-machine interface (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 10M and hubs to 100M 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. Machine builders are adopting Ethernet rapidly because it has proven to work well, handle a variety of applications, and is well known due to its use in the business enterprise.
What Ethernet protocol do you need and why?
EtherNet/IP [an ODVA protocol] is the world’s leading open industrial Ethernet network capable of handling the widest range of applications, including discrete, safety, motion, process, and drive control. EtherNet/IP delivers interoperable Ethernet products from more than 300 vendors, including Cisco, Schneider Electric, Omron, Bosch Rexroth, and Rockwell Automation, providing more than 1,000 product lines and several million installed devices on EtherNet/IP. Because EtherNet/IP uses readily available, off-the-shelf media and complies with IEEE 802.3/TCP/UDP/IP standards and conventions, IT professionals and engineers can collaborate easily to deploy and maintain security, reliability, and quality of service.
Are multiple protocols used on the same Ethernet physical layer?
EtherNet/IP uses standard Ethernet (IEEE-802.x) and standard TCP/IP/UDP. It is an application-layer protocol that can coexist alongside the many commercial and business application protocols used today for web (http), e-mail (smtp), voice, video, etc. EtherNet/IP itself has only one version that supports the many diverse industrial applications named above.
Is the installation new or an upgrade?
Effectively coping with increased demand means ensuring more efficient production methods. Askim Mek Verksted AS, a subsidiary of Glava AS, is one of only a handful of manufacturers supplying cold end glass wool production machinery and manufactures specialist machines designed to package difficult-to-handle glass wool insulation products. AMV’s unique Battpacker system completely automates the entire cold-end process of glass wool production, transforming raw material into palletized, ready-to ship product. The packaging process is a complex one, involving numerous operations, all of which have to be carried out with a high degree of precision and repeatability. AMV has built up considerable expertise in this specialist area, which has seen its Battpacker system gradually evolve as technologies have improved. But for its latest version, AMV took the more radical step of completely reevaluating Battpacker’s control architecture. Battpacker comprises eight separate stages, each one requiring numerous sensors and valves to maneuver the glass wool through each part of the process. Accuracy and repeatability are vital in ensuring efficient operation, minimum wastage, and maximum product throughput. The machine also has to be flexible enough to cope with different types of products and different "recipes" with minimum disruption of production.
Comprehensive system monitoring and diagnostics functions were also vital in ensuring maximum efficiency and uptime. To achieve these objectives, AMV’s engineers looked to replace Battpacker’s Profibus architecture with a state-of-the-art EtherNet/IP solution, supplied by local Rockwell Automation distributor, Triple-S Industry Automation AS. Working with Triple-S, the choice of EtherNet/IP opened up some exciting new possibilities for AMV’s engineers—chief among these being the growing number of manufacturers offering EtherNet/IP compatible products—leading to greater choice. The plug-and-play connection of controllers, actuators, and I/O devices from an increasingly wide number of manufacturers is just a small part of the benefit that EtherNet/IP delivers to machine builders like AMV. EtherNet/IP adheres strictly to the Ethernet standard, allowing users to take advantage of low-cost of Ethernet hardware and cabling. The adoption of the standard Ethernet protocol, rather than a modified version of it, delivers maximum flexibility for machine builders to choose the best components for their application. Because everything from controller to actuator shares a common, single connection, the direct costs of wiring are greatly reduced. The dramatic reduction in wiring bulk delivers significant secondary benefits, such as minimizing the need for cable management and greatly reducing wiring time.
Alongside the tangible cost benefits of a decentralized control architecture, EtherNet/IP allows greatly enhanced functionality. Thanks to EtherNet/IP, virtually every aspect of Battpacker can be monitored for effective maintenance and rapid fault diagnosis, from the operation of the Festo pneumatic valves to the operating temperature of the motors. EtherNet/IP also allows comprehensive remote diagnostics and machine management over the Internet via a secure virtual private network (VPN).
Will the network expand?
Unlike some industrial networks, EtherNet/IP uses the same foundation or infrastructure products as an enterprise network. This means applications like e-mail, video, and voice-over-IP developed for the enterprise can coexist with manufacturing network traffic like I/O and drive control, safety control, motion control, and HMI communication. EtherNet/IP allows machine builders to continuously take advantage of developments in collaborative technologies. In particular, video and voice-over-IP offer significant promise for machine builders and their customers, possibly extending equipment warrantees through advanced diagnostic capabilities and providing opportunities for optimal real-time collaboration.
Depending on project scope and needs, might you be able to do this without relying on IT experts?
Manufacturing engineers and IT professionals rarely see eye-to-eye because their priorities and approaches differ. Manufacturing engineers tend to care most about speed and uptime of equipment, while IT professionals care most about security and reliability of data transmission. With the right design guidance, manufacturers can meet all of these priorities with a single network infrastructure and truly harmonized approach. Rockwell Automation and Cisco are committed to being the most valuable resource in the industry for helping manufacturers improve business performance by bridging the technical and cultural gaps between plant-floor and higher-level information systems. Through successful collaboration on products, services, and educational resources, these industry leaders help manufacturers converge their network infrastructure and tightly integrate technical and business systems using EtherNet/IP—the world’s leading open industrial Ethernet network.
– Mark T. Hoske, CFE Media, Control Engineering, www.controleng.com, and Brian Oulton, director, networks business, Rockwell Automation.
Control Engineering webcasts include more on Ethernet.