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FROM EDN EUROPE: NI simplifies data acquisition with USB

Under the name Compact DAQ, National Instruments has introduced a data-acquisition system based on the connectivity of USB.

By Graham Prophet, Editor -- EDN Europe, 5/11/2006

Under the name Compact DAQ, National Instruments has introduced a data-acquisition system based on the connectivity of USB. The base hardware unit is an eight-slot chassis that accepts a range of hot-swappable, auto-detected instrumentation modules. While not replacing its 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-medium scale, quickly configured field-data-collection system, or as a small-scale ATE 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 required to support up to 256 measurement channels. You can combine low- and high-speed modules in the same configuration—NI says that it is in part the diversity of capable analogue-to-digital converter chips silicon vendors now offer that permits it to build a variety of modules using different ADCs selected for specific tasks. Each module is digitally isolated. Compact DAQ operates from AC supplies or from 11 to 30 VDC.

As might be expected from NI, the system is fully supported within the LabView graphical programming environment, via an open API: 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 up to 24-bit resolution, and as much as 3.2 Msamples/sec acquisition rate. You connect the eight-module chassis directly to a PC with a USB cable—no interface card is required. 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: also, its low latency enables fast command transmission. A base system of host frame and a four-channel, 10-V range measurement module costs in the region of E 1100.