The hardware gets softer

Once upon a time, manufacturing test consisted of collections of rack-and-stack instruments. Engineers attached connectors and twiddled dials to get desired information. The instruments have become more sophisticated, but their basic principles remain. Analog oscilloscopes yielded to DSOs, for example, but a transplanted engineer from that earlier time would still recognize a scope (always remembering the precept offered by science fiction author Ray Bradbury many years ago—"A sufficiently advanced technology is indistinguishable from magic"). Over the last few years, the boxes themselves have begun to fade away. Sometimes the box exists, but at the other end of a phone line from the engineer, who controls it by direct connection or through the World Wide Web. This approach works particularly well for contract manufacturers (CMs). OEM designers can examine manufacturing and test parameters at CM facilities in real time, a huge savings in time and money.

"Virtual" instruments possess no boxes of their own at all. The function resides on a printed circuit board plugged into a conventional personal computer, interacting with the unit under test through the board's I/O.

The instrument's operation is emulated in software—including the traditional front panel. Packages such as National Instruments' LabView, Agilent's Vee, and Geotest's ATEasy serve this category. Sometimes the "instrument" interacts only with another collection of ones and zeros—a product and production line simulation.

With the latest innovation, so-called "synthetic instruments," a generic piece of measurement hardware with a high-speed ADC and DAC at its core is entirely controlled by function-specific software. A piece of hardware might act like a voltmeter one instant, a spectrum analyzer a moment later, and a power meter after that, mimicking an entire rack of expensive stand-alone instruments. The economics of such a solution prove very attractive to prototyping, pre-production, and low-volume/high-mix operations.

Instrument boxes are fading away, with software emulations replacing front panels. Courtesy of National Instruments.

People often contend that "there is nothing new under the sun." Perhaps not, but if you "look under the hood" of these latest instrument architectures, you'll find the hamster running on the wheel is only a hologram.

Steve Scheiber, Contributing Technical Editor sscheiber@aol.com