Module simplifies data acquisition with USB

National Instruments has introduced a data acquisition system based on the connectivity of USB. The basic Compact DAQ hardware unit's eight-slot chassis accepts a range of hot-swappable, auto-detected instrumentation modules. Although the unit does not replace the company's PCI-based instrumentation, NI says that, by exploiting the speed and convenience of USB 2.0, it can address the performance needs of a large fraction of the data-acquisition market.

Compact DAQ, the company says, operates equally well as a small to mid-scale, quickly configured field-datapulse collection system, or as a small-scale ATE (automatic- test-equipment) platform. Modules provide signal conditioning for variables such as voltage, temperature, strain, sound level, and vibration. The system employs four dedicated USB-signal streams to provide the bandwidth to support as many as 256 measurement channels. You can combine low- and high-speed modules in the same configuration. According to NI, the diversity of currently available, capable ADC chips permits the company to build a variety of digitally isolated modules using ADCs. Compact DAQ operates from ac supplies or from 11 to 30V dc.



The LabVIEW graphical programming environment supports the system through an open application programming interface; you can also program it with Visual Basic 6 or with Microsoft Visual Studio .NET. Alternatively, you can use the DAQ Assistant, a setup utility that offers a step-by-step configuration process that generates LabVIEW code. Compact DAQ provides resolution as high as 24 bits and an acquisition rate as great as 3.2M samples/sec. You connect the eight-module chassis directly to a PC with a USB cable; connection requires no interface card. The speed of USB 2.0, NI points out, provides a channel into the PC that is almost five times faster than a 100BaseT Ethernet connection, supporting fast data streaming. The unit's low latency enables fast command transmission. A base system of host frame and a four-channel, 10V-range measurement module costs about 1100 (approximately $1400).

National Instrumentswww.ni.com