skeptics. Increased intelligence is, of course, a good thing, but the devil is in the details, insists Elau’s Jensen. “We do not adhere to the notion of distributing as much intelligence as far down as possible.” Keep the drive as simple as possible, he insists, rather than load it with extra functions that can drive up its price tag and, by overburdening it, degrade its performance.

“The right things to distribute to the servo,” Jensen maintains, “are all servo loop closures, including position. Offloading tasks such as cam tables, however, wastes network bandwidth, takes motion tasks out of the IEC (International Electrotechnical Commission) 61131 standardized world and onto a DSP (digital signal processor), and prevents features such as cam changes on the fly. We advocate a centralized motion and logic control strategy with a distributed motor loop control and motor/drive auto-recognition strategy.”

Others in the industry agree with that general proposition, Beckhoff’s Rawlyk among them. “While our products and solutions can support distributed architectures,” he explains, “our preferred method is to remove much of the intelligence from the servo and drive level. Having just one higher level controller and drives with less integrated intelligence helps increase functionality and reduces required programming time for most applications.”

Rawlyk says that with recent advances in personal computer (PC)-based control technology, “there are very powerful, yet inexpensive centralized control options engineers should consider. When a high-powered PC-based controller is combined with a high-speed fieldbus, a large number of drives can be more flexibly coordinated in various ways.”

How many processing functions should servos and drives be asked to perform? That’s a question that industry pros will be wrestling with for some time, and one that may eventually be answered—or rendered obsolete—by advances in computer technology. But quite apart from the question of precisely where the intelligence should be located, it’s a sure bet that the rising demand for more flexible packaging solutions will fuel the market for more intelligent motion control technology, and vendors will strive to meet those market needs.