still haunts OPC. Some users complain that there are too many transmission failures. Defenders of OPC blame the peculiarities of Microsoft’s authentication requirements for many of these failures. One solution is tunneling, or creating software tunnels through firewalls in order to bypass Microsoft authentication.

Some choose to bypass OPC for specific applications. One example is Acsis Inc., a Marlton, N.J., company that develops product-tracking software. It employs communications libraries from CimQuest InGear, Phoenixville, Pa., to forge connections with Allen-Bradley PLCs from Rockwell Automation.

“The InGear library has allowed us to talk to PLCs directly rather than having to use OPC,” says Ross Levin, director of product development for Acsis. The result, he says, has been “a real-time performance advantage.”

Transitions Optical Inc., Pinellas Park, Fla., a leading lens manufacturer, is another company that chose to bypass OPC. Along with performance advantages that the company believed it could gain through InGear, it was also influenced by the fact that it has many customized systems deployed over five plants.

“OPC is an open source standard, while our company is privately held and uses no open source, so if we used OPC, we would have to change the methodology that we use to interact with our machines on a global basis,” says Patrick LaFerriere, project leader at Transitions Optical.

“When we first get the lenses as raw substrate, we use a laser to put a tiny matrix on the back. That matrix contains the crucial information that will be required as the lens is processed. We use the InGear communication tools to interface with our PLCs, the laser and the production machines.

“When the lens gets to packaging,” he continues, “we use a vision system to read the data matrix and determine what box and what label to use, as well as any special instructions.” LaFerriere notes that the same communication tools interface with customized HMIs that scan every 100 milliseconds to gather data on machine status. The HMIs, in turn, are interfaced with the plant’s MES.

The OPC Foundation, Scottsdale, Ariz., has responded to problems such as these by kicking things up a notch through the launch of OPC Unified Architecture, or UA.

Unlike its predecessor, OPC UA is not bound to proprietary Microsoft technology. It employs Web Services as well as Microsoft .Net in preference to the fast-fading Microsoft common object model (COM) and distributed COM (DCOM). It is capable of handling more complex data and expands the range of OPC, reaching farther down into the control level and farther up into the enterprise systems level. Importantly, its “wrapper” software allows it to work with existing OPC interfaces.

Referring to OPC and other standards, B&R’s Muehlfellner notes, “The needed standards exist. Now it’s up to people to implement those standards. As that implementation progresses, I think it is going to be beneficial for the packaging industry as a whole.”

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