Snap controllers from Opto 22 "snap" into place in I/O racks, though the manufacturer recommends users secure them with a screw.

To simplify troubleshooting on its line of fluid beds, engineers at Fluid Air Inc., Aurora, Ill. (www.fluidairinc.com), replaced a PLC with a Snap controller from Opto 22, Temecula, Calif. (www.opto22.com). The controller uses flow-chart-based OptoControl software that lets operators step through manufacturing processes in real time. This simplifies maintenance and helps pinpoint problems.

"With PLCs, you typically need tech-savvy engineers to sort through the ladder logic and make necessary adjustments to the control system," says Jim McAndrew, Fluid Air director of technologies. "But Opto's software lets almost anyone easily upload their program, make changes, and download it to the controller."

Pharmaceutical companies rely on fluid-bed systems to granulate, dry, coat, and process chemicals into drugs. Every batch in a fluid bed can easily sell for as much as $500,000, and each bed handles up to three batches daily, so it's easy to see why drug makers don't like to see beds down for maintenance. Quickly finding and correcting problems is also a safety issue. "If a fault in the control system or the fluid bed itself potentially adulterates a batch, the risk to the public may be deemed too high to release the product," says McAndrew. "So a control system that is easily understood and maintained is an advantage. And our customers find it empowering to make changes on the fly without depending on one or two specific individuals or the vendor."

Snap controllers connect to operator interfaces or PCs acting as control panels via standard Ethernet and serial or Arcnet cable. This lets operators tweak processes underway in the fluid beds. Snap controllers log all changes and let Fluid Air managers restrict who can alter the process, another safety factor. -- Stephen J. Mraz