Multifunction data acquisition

Last week, National Instruments introduced its new M series of data acquisition modules, effectively replacing its older E series products with a new line of even higher performance cards.

Last week, National Instruments introduced its new M series of data acquisition modules, effectively replacing its older E series products with a new line of even higher performance cards.

Although there are twenty new products in the new range, effectively there are three basic M series ‘platforms’ that each has variants depending on the number of analog inputs, analog outputs and digital I/O that are required by the user.

First off, there is a low cost series of products that can handle up to 32 analog inputs at a rate of 250 kS/sec at 16-bit resolution and four 16-bit analog outputs at 833 kS/sec. All these boards have a minimum of 16 analog inputs, 24 digital I/O lines, and two counter/timers.

Next, there’s a higher speed range that again can support up to 32 analog inputs, this time at a 1.25 MS/sec acquisition rate at 16 bits, as well as a higher 2.8MS/sec output rate at 16-bits. All these boards sport a minimum of 16 analog inputs, 24 digital I/O lines, seven programmable input ranges (±100 mV to ±10 V) per channel, analog and digital triggering and two counter/timers.

Finally, there’s a high accuracy line up that takes advantage of Analog Devices new A/D converters to provide an 18-bit resolution at 625kSamples/sec and a 2.8MS/sec output at 16-bits. Like the high performance versions, these all have a minimum of 16 analog inputs, 24 digital I/O lines, seven programmable input ranges (±100 mV to ±10 V) per channel, analog and digital triggering and two counter/timers. The 18-bit devices also include a programmable lowpass filter, which blocks high-frequency noise from being digitized.

While all the boards in the series have 80MHz 32-bit counter timers, the low cost product clocks its I/O lines at 1MHz, the high speed and high accuracy versions run at 10MHz.

To achieve the performance of the new product line up, National’s designers turned to ASIC technology to provide them with a chip that could control the system timing, synchronization and data routing functions of all input and output DAQ operations.

The NI-STC-2 system timing controller, as it is called, can handle six DMA operations simultaneously – so it can perform analog input, analog output, digital input, digital output, and two counter/timer operations simultaneously while leaving the PC processor free to execute other operations such as data scaling and analysis.

What’s more, the designers also came up with a new type of calibration and linearization scheme to compensate for the inherent non-linearity of the converters on the board. The so- called NI-MCal technology, which is based on a calibration technique that uses third order scaling coefficients, improves measurement accuracy by up to five times when compared to a traditional 2-point calibration.

Lastly, they developed a custom programmable gain amplifier to improve the accuracy of the converters on the board by minimizing the settling time and maintaining the specified resolution of the device even at maximum sampling rates.

Each of the new M Series products includes the latest version of the company’s NI-DAQmx measurement services driver software, which allows system developers to use the new products with NI LabVIEW, Visual Studio .NET and NI LabWindows/CVI software.

More information, including all the product specifications and a white paper on the new technologies employed, is available <link>here=http://www.ni.com/dataacquisition</link>.