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01 October 2001

More fieldbus expertise

Digital technology is the wave of the future.

After reading “Foundation fieldbus disappointment” [June 2001], I would like to share some input based on my experience with bus technology. In the last three years, Foundation fieldbus (FF) has come a long way in terms of acceptance as a viable alternative to HART or 4–20 mA. I remember when people were asking about FF just from a sense of curiosity. Today, people are sometimes requesting bus technology as the only choice. Vendors are realizing they should either be at the forefront of this technology or be obsolete in the near future. Digital technology is the wave of the future, and instrumentation and control was bound to adapt it.

Though the article indicated that savings on cable is sometimes negligible, one has to look at the overall cost of the job rather than just the cable. FF has never stated that cable savings was the sole benefit of this technology. The truth is that when one looks at bus technology and implements a project, the savings are realized in terms of smaller footprint for the control cabinet, which in turn typically means smaller control rooms, smaller and less frequent use of marshaling cabinets, narrower wire trays, and less terminations.

Bus technology also provides savings in terms of faster start-ups and commissioning. There is no need to shut down the segment or system every time a new device is added.

To further installation and start-up savings, device information that is now accessible to operators and electrical and instrumentation technicians makes troubleshooting less time consuming. Digital technology allows a vast amount of information to flow from the devices to the control system. Control systems that were built with bus technology as their platform allow the user to fully utilize the information available. Digital field devices act as servers of information, and not utilizing their full capability when running your plant shortchanges the user of all the benefits of fieldbus.

- Rami Mitri, Mansfield, Mass.