Monitoring multiple data points in complex hardware has been an expensive
proposition, but low-cost solutions are starting to emerge. Simultaneous
sampling is now possible for applications that donít justify high costs.
Measurement Computing Corp. of Middleboro, MA, has expanded its Personal
Measurement Device with a USB-based data acquisition module that it says cuts
costs to 1/7th the price of competing units.
The 8-channel module, the PMD-1608FS, costs only $399 in quantities of 4 or
fewer, dropping to $299 for quantities over 100. That makes simultaneous
sampling available to a broader range of customers. ďWhen youíre doing something
like time domain analysis in an internal combustion engine, you want to know
things all at the same time,Ē says Bob Judd, vice president of strategic
marketing at Measurement Computing.
The unit has simultaneous 16-bit analog inputs with burst rates of up to 200
kilosamples per second, with a continuous rate of 100 ksamples per second. It
has 8 bits of digital I/O and a 32-bit counter.
By comparison, a USB-based
module from Austin, Texas-based National Instruments has 12-bit analog input
resolution and a maximum sampling rate of 100 ksamples per second. †It also
includes 2 analog outputs, 2 24-bit counter/timers, and 8 digital I/O lines. It
costs from $995-$1495, depending on connectivity. (http://sine.ni.com/apps/we/nioc.vp?cid=11922&lang=US)
The Measurement Computing hardware provides a simpler interface than earlier
PCI modules and boards. Both USB 1.1 and USB 2.0 are supported. The module
measures 3.25 x 3.125 x 1 inch. In applications that require security, cable
locks can be routed through an attachment hole in the case.
The PMD-1608FS comes with a range of software. TracerDAQ
functions as an oscilloscope or strip chart recorder, while InstaCal handles
calibration. The program includes drivers for NIís LabView software, giving the
unit access to the broad offerings in that family. Itís also compatible with
Matlab and Labtech.
Measurement Computingís PMD-1608FS offers
simultaneous sampling of eight 16-bit analog inputs, yet it costs only