Chicago—Vendors at the recent National Industrial Automation Show began laying the foundation for Ethernet's migration to the factory floor, thus sending a signal to design engineers to endow next-generation motors, drives, and sensors with onboard Ethernet capabilities.
The Open DeviceNet Vendor's Association (ODVA) took the first step in creating that groundwork when they announced support for EtherNet/IP, an open application layer that interfaces with conventional fieldbuses. At the same time, Siemens Energy & Automation (Alpharetta, GA) said that it would market a so-called "gateway" device that would act as a link between industrial fieldbuses and Ethernet. The gateway device is expected to be introduced by this summer.
The announcements are important for automation users, as well as for engineers who make the components that plug into industrial fieldbuses. Increasingly, engineers who are surveyed on the use of I/O networks designate Ethernet as their choice for the future. A study done by Industrial Controls Consulting (Fond du Lac, WI) revealed that U.S.-based system integrators selected Ethernet by 3:1 over DeviceNet and by 9:1 over Profibus when asked their preference for the primary I/O network of the future. "By far, the preferred industrial network was Ethernet, with DeviceNet a distant second," notes Jon Bullock of Industrial Controls Consulting.
Ethernet was invented at Xerox PARC in 1973, and today is the most widely-used LAN access method.
By using EtherNet/IP, fieldbuses such as DeviceNet, Profibus, Modbus, or others could easily communicate with Ethernet. As a result, information from motors, drives, and sensors could be available to a broader swath of individuals in a manufacturing enterprise. "There's a very large base of people who already understand the use of Ethernet in the office environment," notes Gregory Baker, vice president of corporate development for Woodhead Industries, Inc. (Deerfield, IL) and a member of the ODVA board. "This potentially gives them connectivity from the boardroom down to the factory-floor sensors."
Ethernet would also give users a huge speed advantage over industrial fieldbuses. EtherNet/IP baud rates would range between 10 and 100 Mbit/second. In contrast, DeviceNet offers a maximum speed of 500 Kbit/second.
Still, users aren't expected to gain any immediate benefits from the EtherNet/IP announcement. The reason: Connecting via an application layer such as EtherNet/IP requires that industrial control products have onboard Ethernet intelligence. "While Ethernet is ready now to connect to the fieldbus level," notes Horst Kolbert of Siemens, "the problem is the products aren't ready."
For that reason, Rockwell Automation has announced that it will begin offering EtherNet/IP products within six to twelve months. Siemens, meanwhile, says it will wait until a standard has been broadly accepted and use the gateway as an interim measure in the meantime.