Interested in linking to "Future Fieldbus Trends"?
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.
We automation professionals in a plant environment are a cautious, conservative lot who are slow to adopt new technologies unless the benefits are concrete and the risks low. Therefore, these predictions might be a bit less rosy (but hopefully more accurate) than those espoused in the glossy, color marketing brochures and the flashy articles written on the hottest technology du jour.
When Foundation fieldbus and Profibus-PA first were introduced in the early 1990s, they were expected to revolutionize industrial control and render 4-20 mA instrumentation obsolete within a few short years. Nearly 20 years later, fieldbus devices still make up a small fraction of the installed base and well fewer than 50% of new installations.
One of the reasons for slow adoption has been addressed. The major organizations finally are at work on a common standard with similar device files, etc. However, the rapidly increasing cost of fieldbus hardware and licensing software, especially for Foundation fieldbus and Profibus-PA, is stifling future growth. The increases are not the result of manufacturing cost hikes, but mainly because people are willing to pay the difference and automation vendors are looking to capitalize.
At this point, fieldbus solutions equal or exceed the cost of traditional I/O and the touted savings simply are not there. Hopefully, recent attempts to adopt a common device definition file and falling control chip costs should allow the vendors to create a single device that can operate on either Foundation fieldbus or Profibus-PA systems. When that happens, competition should drive down fieldbus device costs significantly, and the rate of adoption will increase.
Wireless instrumentation will grow, but not nearly as fast as the current predictions suggest. Fundamentally, wireless has value in tank farms and similar monitoring applications. But control over wireless for a process plant simply makes no economic sense. In a plant of any size, one outage caused by lightning, radio interference or a failed battery will often pay for all the wire saved in the original installation. Wire installation is a one-time cost, and when considered over the life of a 15-year instrument, it is a small part of the total lifecycle cost.
Ethernet will continue to grow, and I expect many of the current high-speed communication protocols (Profibus-DP, ControlNet, etc.) will migrate in some manner toward the Ethernet hardware layer. Some might argue about the need for determinism, but as the network speeds increase, the response is becoming so quick that the issue of deterministic data transfer is nearly moot.
Power over Ethernet (PoE) is going to play an increasing role in automation and control. In the long run, I could see the low cost of switches and high-speed communications pushing the industry toward some kind of common high-speed field network with self-healing rings and power available straight off the network. Field devices will be assigned addresses as they plug in and the control system will query the field device and pull up a configuration menu straight off the device—finally eliminating the needless pain of chasing down the latest GSD/EDS/CFF file.
All of these changes will happen slowly. With millions of 4-20 mA instruments in reliable, trusted and supportable service today, the risk of changing to the new technology will need to be more than offset by the benefits to the plant's bottom line. As such, the industry as a whole will be in no hurry to migrate in a new direction. Plants will continue to try new technologies in small projects, and gradually will adopt those that offer intrinsic value and payback.
In the meantime, magazine articles will continue to be written hawking the latest trend and promising global acceptance “in a few short years.” I feel pretty certain about that last prediction.
P. Hunter Vegas, PE, is senior project leader at industrial process control system integrator Avid Solutions (www.avidsolutionsinc.com), based in Winston-Salem, N.C. Vegas and his colleagues have engineered and installed many fieldbus systems in many different industries.