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Data-acquisition boards and modules of offer designers an embarrassment of riches, as performance and feature sets advance in lockstep with PC and chip technology. In the last few years, vendors have been busy reformulating cards for the latest PC buses-notably, PCI-so that users can take advantage of their speed, bus mastering or other new capabilities. They have also poured effort into software-both the drivers and application, or programming, software that are responsible for much of the performance and personality of today's boards.
Recently, the DAQ arena has seen a few new twists. For notebook or laptop PCs, sophisticated capabilities are being tucked into PCMCIA cards, a notable packaging feat, as portable data acquisition becomes more widespread. And at the high end, the Universal Serial Bus is beginning to make its way into PCs, opening up an entirely new set of possibilities for data acquisition.
The sweet spot of the data-acquisition market falls between 12 and 16 bits of resolution and perhaps 100-kHz operation. That is where board shoppers will find the more popular families, such as the extensive lines at ComputerBoards and Daytronic, Data Translation's DT-300 and DT-3000, Intelligent Instrumentation's PCI-2000, Keithley Instruments' extensive Metrabyte line and the voluminous National Instruments E and other series.
However, these represent only the typical boards. The PD-MF-330/12 from United Electronic Industries, for example, moves 12-bit data along at a 330-kHz clip, and Analogic's boards top 800 kHz. IOtech has offered 1-MHz digitizers for years, and others are moving up as well.
Chase Scientific has a 14-bit ISA card, the multifunction AD210-12, which zips along at 10 Msamples/s and boasts 14-bit resolution. And in the A/D converter speed race, Gage Applied Sciences has blazed away from most others with boards like its red-hot, two-slot CompuScope 1016, a 16-bit performer that samples at up to 10 MHz.
Typically, however, faster boards come at lower resolutions, and slower boards at higher resolutions. A case in point is the Chase Scientific Diamond-MM-250M, which sucks in data at 250 Msamples/s, but with 8-bit resolution. Chase bills the unit as "the world's fastest PC/104 data-acquisition module."
Will acquisition speeds continue to climb? Most likely. According to Skip Cook, director of product operations at Keithley Instruments (Cleveland), "upgrading is on everyone's mind because of the...