Training Wheels for Fieldbus

Feb. 6, 2009
Even in Lean Times, There Are Ways to Get a Fieldbus Testbed If You Think Creatively
By John Rezabek, Contributing Editor

Many early adopters have relied on trial and error and supplier or main instrument vendor (MIV) expertise to get from ignorance to competence in fieldbus and related technologies. Some of us have seen some value in having a “training” system―a mini-simulation of what we’ll be installing in the real plant.  By acquiring and interconnecting the rudimentary DCS components controller, fieldbus H1 card or linking device, power supplies and engineering interface/operator interface with a representative selection of field devicesthe opportunity for education, testing and experimentation is significant.

At the Houston office of Bechtel, then-chief engineer David Lancaster had his group assemble prototype systems that now span several systems and many field devices. Beginning with its first Foundation fieldbus (FF) projects in 2001, Bechtel added relevant system components and devices as required and “played” with them, gaining proficiency in the skills that would be needed at FAT and when the systems were commissioned in the real plant. Nuances such as fastest macrocycle times and effects of downloads/changes were explored well in advance of “go-live” with real measurements and controls. Procedures were tried out and faults simulated without affecting running process.

Now teaching Foundation Fieldbus classes at Trine University in Angola, Ind., Lancaster says “Having this type of facility, with multiple hosts, wiring components and field devices by many manufacturers, has made Bechtel an industry leader in the design and implementation of Foundation Fieldbus.”

If you’re part of a smaller firm, building such a prototype system can be challenging. Do you ask a client to fund its acquisition? Even if you’re successful, chances are the prototype will head to the client’s site for its own use. But if your shop is focused primarily on a single host system’s offerings, then it benefits both of you to have some substantial investment in a demo and training system, both for prospective customers and formal training courses.

Field devices, while individually less of an investment, quickly can drain anyone’s budget for non-billed incidental expenses and investments. There’s a little more leeway for operator and engineering workstation hardware, however specific licensing to unlock systems features may be prohibitively expensive.

BP used another path, when it operated chemical plants in Lima, Ohio. Seeing a need for continuing education of its own employees, prospective employees and the contractor workforce, BP donated sufficient funds to the local technical college to allow it to procure a nice assortment of systems hardware and field devices. It also donated the technical expertise to get the systems hooked up and operating. Other suppliers offered their hardware at special pricing and providing licensing at reduced or zero cost. In a similar fashion, BP donated a sizeable sum to help create and expand a similar (and much larger) lab at SAIT Polytechnic in Calgary, Alberta.

Current economic stress may make such generosity a pipe dream. However, economic downturns can also mean idling or scrapping some assets. You might find an early-adopter’s fieldbus system in their boneyard.
Finally, end users can create a sandbox in the midst of their physical plants. An unimportant or rarely used segment in a typically idle part of the process can still be a test bed for allaying fears and insecurities of operators and technicians. Physical layer components can be abused, and one can push the limits of segment length, spur length, total devices and macrocycle times, all using spare parts or idle hardware. A segment run into a shop area for training or dead-weight calibrations can also be exploited in this role.

No matter how you get there, the benefits of having a small systemavailable early on the road to digital integration of field devices and throughout the life cycle of your projects and plant is well worth the effort and expense.