Electronic Design

PC-Based HW/SW Tools Aid Design And Test

Next-generation data-acquisition hardware and interactive test software in PC-based instruments raise performance levels yest still lower costs.

"We need more speed and accuracy!" say design and test engineers who work with PC-based instruments. Of course, the price for that performance must be within reason.

Paying heed to that cry, National Instruments came up with the M series next-generation, multifunction, data-acquisition (DAQ) modules, which promise increased accuracy and faster sample rates along with a reduction in cost per I/O channel by more than 30%. The modules also minimize setup time thanks to advanced development tools. In addition, the company attempts to more closely link design and test via its SignalExpress interactive software package. The software accelerates tests needed to verify and validate a design and lets designers combine design simulation data with actual measurements.

The DAQ modules are based on the company's NI-STC-2 custom-designed system-synchronization and timing-controller ASIC, which incorporates clocked and correlated digital I/Os as well as quadrature encoder inputs (see the figure). The ASIC also integrates the NI-PGIA 2 custom-designed gain amplifier for improved measurement accuracy and faster acquisition rates, plus the NI-MCal revolutionary calibration and linearization methodology. The modules offer breakthroughs in accuracy, sampling rates, number of I/O channels, and lower costs/channel, compared to the predecessor E series.

The M series includes four product variants: two with 16 analog inputs (one of which has no analog outputs and the other with two analog outputs), and two with 32 analog inputs (one of which has no analog outputs and the other with four analog outputs). Analog 18-bit inputs are available for higher accuracy. The series is categorized by three types of families—low cost, high speed, and high accuracy—that all feature 80-MHz, 32-bit counter/timers.

For low cost, users can select from a 16-bit analog input with a 250-ksample/s rate; a 16-bit analog output with an 833-ksample/s rate; and a 1-MHz digital I/O. For high speed, the choices are a 16-bit analog input with a 1.25-Msample/s rate (1-Msample/s scanning); a 16-bit analog output with a 2.8-Msample/s rate; and a 10-MHz digital I/O. For high accuracy, options include an 18-bit analog input with a 625-ksample/s rate (500 ksamples/s scanning); a 16-bit analog output with a 2.8-Msample/s rate; and a 10-MHz digital I/O.

With the NI-STC-2 controller, up to six operations can be executed simultaneously at rates five times faster than previous NI devices. The NI-PGIA-2 programmable amplifier dramatically reduces settling time to ensure accurate measurements at fast scanning rates. And, the NI-MCal calibration and linearization technology boosts measurement accuracy up to five times and extends the recommended calibration interval up to two years.

SignalExpress is an interactive software environment for acquiring, comparing, automating, testing, and storing measurement signals. Providing a virtual instrumentation environment for benchtop instruments, it saves time by automating measurements for design, debugging, characterization, and validation tasks.

SignalExpress can be used with any programming code or development environment. Projects can be converted to LabView VI from the interactive environment.

The software includes 25 built-in steps for generating and acquiring signals from a wide variety of hardware. It provides interactive alignment, filtering, averaging, and scaling measurements and features time-domain amplitude, level, timing, transition, and histogram measurements. Power, frequency response, and distortion measurements can be made in the frequency domain. Sweep operations and limit testing are possible as well.

User-defined LabView VI steps can be executed from the interactive environment. ASCII, LabView Measurement File (LVM), and simulation results from EDA tools can be imported and subsequently exported to ASCII and LVM files.

Pricing for M series DAQ modules starts at $375. SignalExpress software costs $995.

National Instruments Inc.
(800) 258-7022

See associated figure

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