What exactly is an open control system? If it has an Intel chip and runs some flavor of Windows, does that mean it's open? Is 'single-vendor, open system solution' an oxymoron? When you buy an open control system in pieces from different vendors, who takes responsibility for the system?
I called some of the companies who are promoting open control. I asked for a definition of open system and here's what they said:
Brian Brickhouse, Cutler-Hammer Automation, said, "We feel a system must be open at all levels, that is, at the controller level as well as at the device-level network below and the cell-level network above. Having an open system means that every component is multi-vendor available because in today's world it's not possible to find everything from a single vendor. The requirement is for a 'bolt-on' technology to give the customer the ability to use best-in-class components."
Ted Wodoslawski, Rockwell Automation, offered, "Open doesn't always mean PC-based. Although PC-based control systems are typically open, many proprietary PC-based control systems have been created and as a result some users have gotten wedged into one company's open system solution. A control system that modifies Windows NT is no longer an open architecture; it is a proprietary PC-based control system."
John Ham, ObjectAutomation, commented, "An open system is where you expose the interfaces to your product so third parties who aren't associated with you can write software for it. Object systems, in general, encapsulate functionality so others can use it, without knowing what's inside."
From Reed Hornberger, Sun Microsystems, I heard, "An open control system can be accessed from and publish to any platform or device throughout the corporate Internet or intranet."
Marcus Schmidt, Microsoft, said, "An open system is based on generally accepted standards. Industrial automation (IA) will eventually be inundated with information technology (IT) standards due to the economies of scale. Eventually IA and IT will converge around a set of high-volume technology standards."
Currently, open control systems tend to reside in boxes. With Java or Windows CE, computing power comes down to the level of the sensors and actuators. According to Ham, "As Windows CE emerges, control will come off the PC and into dedicated control devices." Wodoslawski reports that Rockwell currently has a number of Windows CE developments underway to provide hard real-time control and a platform for small footprint systems. Sun's control system strategy, as explained by Hornberger, is based on Java's platform independence and scalability. Within the next two to three years, he expects the control system to be on the sensor.
Certainly, the IT world is already having a significant impact. But IA isn't about word processing, spreadsheets, or missing a payroll. Faulty control systems can kill people. In IA, the word 'crash' can have a different meaning. The key is the application of all the technologies, including those from IT, to create an effective control system. This lands us squarely on the issue of system responsibility.
Wodoslawski believes some users are taking too much responsibility on themselves. Rockwell is responding with bundled systems, "so customers get the benefits of open systems but have someone to take responsibility." It appears that 'single vendor, open system solution' is not an oxymoron.
Cutler-Hammer will accept responsibility for multi-vendor systems. "If a customer wants a system with products from several different vendors and someone to stand behind it, we'll put it together and take responsibility," says Brickhouse. "That doesn't mean we're competing with systems integrators. We work with them as partners." Schmidt sees the responsibility issue as "a wide open opportunity for systems integrators." He believes that end users are quite willing to pay for those services because of the security it appears to offer.
Perhaps that's true. A larger issue is whether they feel as secure when an integrator takes responsibility for the system as they do when the control equipment manufacturer is on the hook to make it work.