News and New Products

Units underscore importance of USB-based modular instruments

By Dan Strassberg, Contributing Technical Editor -- EDN, 6/6/2008

The U2700A series turns USB into a plug-in modular-instrumentation platform. The portable chassis at top, which you can also mount in an equipment rack, houses and powers the modules, which you can also connect individually to a host PC. The chassis provides facilities for synchronizing the operation of the modules it contains. Included software (bottom) makes short work of common functions, such as specifying waveform parameters.

Agilent has underscored USB’s importance as an instrumentation platform with the addition of digital-oscilloscope and waveform-generator modules to an already broad, but little publicized, line of USB-based plug-in instruments that you can also use as stand-alone units. Although several data-acquisition-equipment manufacturers offer USB-based instruments that depend on a host PC for their operator-interface and control functions, you may not have heard about USB-based modules that you can connect individually to a host PC or plug into a chassis. Such a chassis is Agilent’s $1186 U2781A, which contains a USB hub and incorporates an ac-operated power supply because some modules use more power than the bus can provide. It also includes synchronization facilities for as many as six 1-in.-wide, 4.13-in.-high, 6.87-in.-deep resident modules, some of which may occupy multiple slots. The chassis’ master/slave-triggering capabilities enable synchronization of nearly all slotted modules, even those that perform different functions. By removing hardware that protects against mechanical shock in portable-system applications, you can fit the 10.63-in.×7.76×10.68-in. chassis into a 4U, 7-in.-high rack space. For engineers who design compact moderate-performance instrumentation systems for use in development and production testing, the availability of this chassis and the large and growing module family marks USB-instrument modules as potentially worthwhile alternatives to PXI (PCI extensions for instrumentation) and similar units.

The new USB modular instruments include the $1329, 100-MHz-bandwidth U2701A and the $1638, 200-MHz-bandwidth U2702A oscilloscopes, which offer sampling rates to 1G sample/sec; the $1638, 20-MHz U2761A function generator, which produces sine, square, triangular, pulse, ramp, exponential, modulated, and arbitrary waveforms; the $2165, three-channel U2722A source/measure unit, which offers four-quadrant source and measurement capabilities for parametric testing, including test-point and resistance measurement and current- and voltage-sourcing and measurement; and the $936 U2751A switch matrix, a four-by-eight-point, two-wire design with 32 channels that provide additional test points for functional tests.The included Modular Instruments Measurement Manager software enables measurements without programming thanks to a graphical interface that provides user-friendly configuration and makes functions easily accessible. Bundled drivers allow you to program with Agilent VEE, C#, C++, Microsoft Visual Basic, or National Instruments LabView.