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 don't 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.
(http://www.measurementcomputing.com/cbicatalog/cbiproduct_new.asp?dept_id=352&pf_id=1572&mscssid=QWRSDQCA91TC9KND8PWAC36MBDD5D2MD
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. "When you're doing something like time domain analysis in an internal combustion engine, you want to know things all at the same time," 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 NI's LabView software, giving the unit access to the broad offerings in that family. It's also compatible with Matlab and Labtech.