Interested in linking to "The Network in Your Future"?
You may use the Headline, Deck, Byline and URL of this article on your Web site. To link to this article, select and copy the HTML code below and paste it on your own Web site.
By Jim Montague, executive editor
Some futures are better than others. Naturally, the trick with industrial networking, and most endeavors that invest in the future, is to pick the right path now to achieve the best outcome later.
Not easy—especially for users, engineers, system integrators and suppliers trying to cope with the constantly shifting terrain of industrial networking. It's all most folks can do to keep up with the present—or yesterday for many of us. Few, if any, have time to speculate or bet successfully on what's going to happen to industrial networking five or 10 years down the road. Fortunately, to handle present tremors and upcoming upheavals, there is plenty of helpful advice and many useful resources. Ironically, one of the best may be a cold splash of reality, and then a clear-eyed look at industrial networking's recent past as an indicator of its likely future.
"Everyone believes Ethernet in some form will be what all the analog and fieldbus networks will head toward in the future because it's fast, simple, inexpensive and ubiquitous, and because users can just give their devices an address on their network and be done with it," says Hunter Vegas, senior project engineer at Avid Solutions (www.avidsolutionsinc.com), a system integrator in Salem, N.C. "However, despite all the marketing brochures and CEOs at conferences, the process control-related industries still move very slowly. Twenty years ago, 4-20 mA was supposed to be dead because buses were going to change everything in five years. Well, even today, all the fieldbuses together don't add up to more than a fraction of all industrial networks. This is because, if you lose enough instruments and your plant shuts down for a couple of days and you lose $2 million dollars, then the $100,000 you saved on wiring doesn't matter. It's still difficult and costly for fieldbuses to achieve this kind of redundancy, and users still aren't going to walk away from the thousands of hardwired instruments they have in place."
Despite these drawbacks, Vegas adds that some networking protocols, like lower-level Actuator Sensor-interface (AS-i), help reduce costs because they're simple and easy to implement, and they don't require users to do as much engineering as other fieldbuses. He explains that all industrial networks must strive to be almost as easy to use as 4-20 mA if they hope to replace it in the years ahead. "Many instruments and fieldbuses are leaving the average technician behind," says Vegas. "I know a dozen plants where, if a transmitter fails, they have to call in an engineer. In the past, if a 4-20 mA line failed, anyone could go hook up a new one and get the system running."
As a result, Vegas reports that some networking design tools and hardware are becoming easier to use, and this is the direction that users need their suppliers to follow. "For instance, users can adjust AS-i networks on the fly with a lot less pain than before. We also have handheld AS-i readers that are very plug-and-play because they allow us to assign numbers to nodes, punch in those numbers, and immediately get a reading from that particular switch or device. New fittings and blocks also make it a lot more like using 4-20 mA. It's also good that users now can buy fieldbus transmitters and plug in whatever chip they need into that common device. I think we're going to see more common devices like this soon, too."
Likewise, a lot of networking hardware is getting easier to mix, and this will continue, says Vegas. "For instance, you can run Profibus or DeviceNet out to a particular area and use gateway converters to immediately convert to AS-i at your field devices," he says. "Also, the buses are getting easier to deploy because you don't need as many special cards or licenses, and this helps to accelerate their use."
Because of their varied legacy equipment and newly required capabilities, many process applications increasingly need networks and strategies that allow all these controllers and other devices to talk to and interact with each other and—you guessed it—do it faster and easier, too. Maybe comprehensive interoperability isn't too far off either?
For instance, Caeté-Matriz Distillery, part of Grupo Carlos Lyra (www.carloslyra.com.br) in Alagoas, Brazil, recently upgraded its huge sugar and ethanol plant from 4-20 mA/HART to Foundation fieldbus (FF) High-Speed Ethernet (HSE) and Profibus as an alternative in its classified and motor control center (MCC) areas, and used a Smar distributed control system, client-server schema and flexible function block (FFB) software to coordinate and optimize its various installed and legacy equipment and systems. Meanwhile, plant supervision is performed by a GE Fanuc HMI/SCADA system, which uses redundant database servers to communicate with the controllers via OPC in real time.
To integrate its new and existing equipment, Caeté-Matriz's fermentation process uses a Smar controller that functions as a Profibus-DP master and a HSE remote I/O (RIO) at the same time (Figure 1). It controls the fermentation process by automatically injecting defoamers and backwashing the fermentation tank's heat exchangers. In general, these Smar controllers have native and redundant HSE connections that provide twin 100 Mbps connectivity. Because FFBs in HSE controllers provide data between analog and discrete controls, it's possible to use FFBs to create HSE links between controllers and integrate analog and discrete controls.