Voices: Rezabek

Forays into Fieldbus Technology Pay Off

Plenty of Training Resources Available to Get Team On Board

By John Rezabek

Back around the time smart transmitters were becoming mainstream — 1989 — Keystone beer introduced an ad campaign touting its, well, relative lack of flavor. The beer delivered refreshment guaranteed to minimally challenge one's palate. In the ad, a quaff of “bitter” beer sent its subject into facial contortions, revolting to all who witnessed them. Better flee to an insipid, corn-adjunct-diluted brew.

There are those who've taken a sip of fieldbus technology, experienced an episode of “bitter beer face,” and remain unwilling to go near it since. Unforeseen struggles with a supplier, service provider or technology can be enough to quash any inclination to get another six-pack.

But what if you want to escape the bland world of 4-20 mA? If you have a thirst for an all-digital, 21st-century process control infrastructure, you'll encounter many who consider forays into new technology—for example, digitally integrated field devices using an open standard—a gamble with too much chance of potentially bitter consequences. How do you convince these folks to try a sip of your proposed brew?

Training: Training junkets aren't just about learning technology. They're also for learning about each other, and gaining an appreciation of your end users' fears and challenges. If it's a class with attendees from other locations, you both have a great opportunity to learn things from them and share war stories. It can be a great comfort for your plant's guys and gals to see they're not the first pioneers on the prairie, and often you—and they—will learn as much or more from your peers as you do from the course material. Sessions should not be restricted only to specialized training focused on fieldbus. They should include training from systems suppliers (once they're chosen), asset management system providers and possibly device suppliers as well.

Device Replacement: Device replacement has been distasteful for a lot of end users, especially when they need to call an engineer when a device or fieldbus segment needs downloading. In Foundation fieldbus (FF), by design, devices come out of the box as blank slates with minimal configuration. The idea is that a centrally stored database in the DCS is a more desirable repository to preserve a consistent device configuration. But complications arise when instrument technicians are neither trained nor permitted to perform any operations on the DCS. Other complications ensue if the device checked out of the storehouse is a later revision than the one originally installed. If they don't match, the system configuration requires sediting, and sometimes new device descriptors (DDs) have to be downloaded. This is particularly onerous for remote sites with dicey Internet access. Bitter beer face!

The Fieldbus Foundation is addressing this issue today, beginning with a specification called compatibility_rev. Devices and host systems employing this parameter will allow a new device to be commissioned as an earlier revision—all the way back to the revision specified by compatibility_rev. It works like this: If your project installs Revision 3 of a transmitter, when the storehouse restocks with the latest revision, this new device can still be commissioned as Revision 3 without installing a new DD or changing the system configuration. A number of systems and device suppliers have begun creating tools and wizards that exploit this feature. It's been an optional feature since ITK5 devices, but consideration is being given to making it mandatory before the next major update.

When taking your first sip of fieldbus “beer,” you don't need to brace yourself for a bitter experience. There are plenty of training resources to get your team on board, and the Fieldbus Foundation's focus on H1 usability aims to make FF as simple as old 4-20 mA. Once you've trained your palate, you'll wonder how you ever put up with the bland brews of yesteryear.

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