SOMEDAY, industrial networking will be simple. Someday, electronic data packets will move effortlessly and securely from thousands of I/O devices in the field or on production lines, up through the plant floor and control room, and on to enterprise users and beyond. Someday, users will plug-and-play their devices without even having to think about interoperability, configuration, and programming.
Someday—just not today. That’s because despite recent cooperation on electronic device description language (EDDL) technology by three major fieldbus organizations, despite the recent emergence of several other networking protocols and methods, despite multiplying Ethernet flavors, despite evolving wireless standards, and despite new efforts promising even more interoperability, users still don’t have the completely open, interoperable, easy-to-use networks they need.
Selfish, proprietary interests continue to hold uninformed users hostage by subtly feeding their fears about new networking technologies, and then adding unnecessary layers of complexity to fieldbus protocols to confirm those fears. This traditionally is done to “protect users’ investments in their installed base,” which actually means “protecting the market share of suppliers too lazy to truly invest in innovation.” The now-classic example of this was the International Electrotechnical Commission’s (IEC) 61158 standard, which was hijacked years ago, and ended up with eight, non-consensus, ineffectual parts. Though most suppliers and their related trade organizations developed and now promulgate their own Ethernet versions, some proprietary snags are starting to surface in efforts to develop and settle on a wireless networking standard.
Tapping Untapped Interest
However, all is not lost. Surging end-user interest in Ethernet and wireless technologies is stoking interest and adoption of fieldbuses and other networking technologies, rather than replacing them as might be expected. This likely is happening because the sheer volume of users of 4-20 mA and other hardwired networks still is about four or fives times as large as all of those using twisted-pair fieldbuses, industrial Ethernet, and wireless combined.
Many users in this huge, untapped market initially are attracted to Ethernet and wireless, but often settle on fieldbuses, which are perceived to be more reliable and less scary, but still able to generate the wiring and labor savings they’re seeking.
“Everyone expected Ethernet to supplant other networking methods, and that might happen in 10-20 years,” says Katherine Voss, executive director of ODVA and ControlNet International (CI). “However, at this moment in 2006, it appears that industrial Ethernet actually is causing all our other networking technologies to increase as well. So, while our EtherNet/IP protocol is growing by 30% per year, we’re actually seeing double-digit increased for all our CIP-based protocols, including DeviceNet and ControlNet, and we’re seeing a lot of hybrid networks.”
Voss thinks the ubiquitous adoption of Ethernet and Internet technologies in business and technical applications is the main inspiration for more users exploring and implementing newer networking technologies in control and automation. “For example, the fact that CIP can exist on the same wire and device at the application layer in Ethernet and Internet topologies makes it a very useful way to connect the plant floor to the enterprise, and this makes a good value proposition for all kinds of fieldbus networking.”
In probably the most genuine collaboration effort, Fieldbus Foundation (FF), Profibus Nutzerorganisation e.V. (PNO), HART Communication Foundation (HCF), and the OPC Foundation have been working jointly to extend the text-based Electronic Device Description Language (EDDL) specification and language they use to describe characteristics of networked field devices. EDDL is international standard IEC 61804-2. Proposed extensions to DDL included adding capabilities to describe display characteristics of device parameters, as well as the ability to include algorithmic relationships for complex device parameters, persistent data, and real-time trends. These were approved as IEC 61804-3 earlier this year.
Ron Helson, HART Communication Foundation’s executive director, says the newly enhanced EDDL simplifies and standardizes the presentation of intelligent device information for automation suppliers and users worldwide. “These enhancements allow manufacturers to easily incorporate graphical windows, menus, images, trends and other advanced data visualization features into the DD for display on compliant host application platforms,” he states. “All information to define the window, the presentation of data within the window, and interaction with the device is described entirely within the enhanced DD. The enhancements also support storage of historical data from field devices for troubleshooting and diagnostics.”