DAQ Technologies Support Broad Measurement Range

Data-acquisition hardware and software systems provide enhanced acquisition and analysis capabilities across a wide variety of applications from industrial control to life sciences. The available systems range from largely self-contained ones that support a limited number of modules and I/O capabilities to flexible modular approaches that can be expanded almost without limit to serve very high-channel-count applications.

DT8875 and DT8876 MEASURpoint Systems
Courtesy Data Translation

In addition to selecting sensors, signal-conditioning circuits, and DAQ mainframes, you’ll need to decide what to do with the data you capture. To that end, you can select systems with a variety of connectivity options.

VTI Technologies embarked on a major expansion of its DAQ lineup in February, according to Anirudh Narayanan, lead applications engineer. The new EMX series, he said, builds on the company’s legacy as a supplier of DAQ and modular instruments.

Specifically, he explained, the EMX series is a modular, Ethernet-based platform with a high-speed switched serial backplane for extremely fast, low-latency data transfers. It includes a PXIe mainframe as well as the EMX-2500 PXIe-Ethernet bridge; the EMX-4350, a four-channel, 625-kS/s, 24-bit smart dynamic signal analyzer; the EMX-4250, a 16-channel, 204-kS/s smart dynamic signal analyzer; and the EMX-1434, a four-channel, 204-kS/s, 24-bit arbitrary waveform source. The EMX series, he said, is a part of VTI’s SentinelEX family of DAQ solutions, which also includes the EX1629 for bridge and voltage measurements; the EX10xx for temperature, voltage, and general-purpose DAQ applications; and the EX1200 scanning DAQ platform.

Narayanan said the new products have grown out of VTI Instruments’ 25 years as a DAQ solution provider, during which time the company has found its products used in “…virtually all application areas—MIL/Aero, industrial, and laboratory.”

New DAQ Architecture

In 2011, Dewetron introduced the DEWE2 series, which Grant M. Smith, president, described as a completely new architecture for the company. “The big distinction is that, in all previous series, we had separate signal-conditioning and A/D cards,” he said. “By combining them into single modules that plug in very much like taller PXI cards, we accomplished several important things,” including increasing accuracy by up to 400% by eliminating all wiring and interconnections between the signal conditioners and A/D card.

xDAP System With DAPtools 6 for Native 64-Bit Windows 7 Applications
Courtesy of Microstar Laboratories

Smith added that the new system offers improved shock and vibration specs by completely eliminating the PCI cards used in the previous-generation system. In addition, he said, in the new series the ADCs now are 24-bit with automatic anti-aliasing filtering on all channels to further improve performance.

Tami Pippert, product manager at Agilent Technologies, said the company’s DAQ products have been used across a broad category of industries (including aerospace/defense, laboratories, communications, and industrial) to serve in product characterization (involving environmental testing, thermal profiling, and stress tests), design verification, and process monitoring (quality control). The DAQ products include the 34970A/34972A three-slot mainframes and the 34980A eight-slot modular mainframe. Both the 34970A/34972A and 34980A DAQ platforms offer internal 6½-digit DMMs, an easy-to-read display to monitor the setup and measured values, and an easy-to-use front panel for manual setup control.

The platforms provide various connectivity options, including GPIB, for flexible interfacing to a PC. USB and LAN (LXI) are available on the 34972A and 34980A platforms as is remote access with a built-in web interface. All the platforms support the SCPI programming language, with drivers and datalogger software included.

According to Kristin Sullivan, Data Translation’s product marketing manager, “Data Translation extended the features of our most popular product lines to address customer-identified application needs: higher isolation to preserve signal integrity in high-noise environments, comprehensive application software with intuitive GUI to increase immediate productivity, higher throughput speeds to extend feature capabilities, and enhanced third-party software support to improve user experience.”

Recent products from Data Translation include the DT8875/8876 high-isolation Ethernet instruments, additions to the MEASURpoint product line that uses the company’s ISO-Channel design. As Sullivan explained, ISO-Channel technology combines a 24-bit ADC per channel with ±500-V, ±1,400-V, or ±3,500-V isolation between all inputs and to earth ground for accurate, simultaneous DAQ. “Common-mode noise and ground loop problems are eliminated since sensors at different ground reference levels are easily accommodated, even if they are at widely differing voltages of hundreds of volts or transients to thousands of volts,” she said, adding that the technology is a feature on all of Data Translation’s Ethernet products and several of its USB products (including the DT9824 and DT987x).

Sullivan further explained that many Data Translation modules feature simultaneous acquisition. “Simultaneous acquisition means each analog input has its own ADC to eliminate phase shift between channels and to allow you to correlate measurements at the exact same instant in time,” she said.

Recent software enhancements from Data Translation include the MEASURpoint Framework application, which supports DT887x and DT987x instruments. It enables acquisition of thermocouple, RTD, and voltage data from multiple instruments with data plotted, digitally displayed, or recorded to disk. In addition, the company introduced LV Link 3.0, a library of VIs that enable National Instruments’ LabVIEW programmers to access the DAQ features of DT-Open Layers-compliant USB and PCI devices. LV-Link 3.0 features native support for 32- and 64-bit NI LabVIEW.

USB and Ethernet Connectivity

National Instruments is targeting a variety of connectivity options with its recent DAQ products, according to Chris Delvizis, product marketing manager for data acquisition. Such products include the one-slot NI CompactDAQ Chassis for USB, Wi-Fi, and Ethernet. NI also is emphasizing software capabilities included in NI LabVIEW 2011 and NI DIAdem 2011 for DAQ applications, he said.

xLabScribe2 Software and the IX-404E DAQ System
Courtesy of iWorx

Delvizis explained the latest version of LabVIEW adds programming and productivity features to improve users’ application efficiency and performance. It includes new features such as modern-looking UI controls and indicators and 20 math and signal-processing functions plus 13 based on user feedback. DIAdem software, he said, is designed to help engineers quickly locate, inspect, analyze, and report on measurement data using one software tool, offering efficiency gains and scalability with capabilities that overcome the limitations of office programs like Microsoft Excel.

Mike Hoyer, applications/marketing engineer at HBM, said his company’s efforts over the past year have yielded additions to the Genesis HighSpeed platform. These include 16- and 32-channel, 24-bit, 20- kS/s and 250-kS/s DAQ cards offering IEPE (integrated electronic piezo electric) and charge support, TEDS (transducer electronic data sheet) support, digital I/O capabilities, and single mainframe channel counts ranging from 512 in the GEN16t rack mainframe to 64 in the portable touchscreen GEN2i. The GEN2i, said Hoyer, enables 64 channels that can easily be carried around for onsite maintenance, troubleshooting, and R&D applications.

In addition, HBM recently introduced a new module—the CX22W—for its QuantumX compact DAQ system. The CX22W enables standalone measurements, without the need for a tethered computer, for mobile or stationary applications. Also new from HBM is the espressoDAQ platform, which includes USB DAQ modules that are highly compact with integrated signal conditioning.

Measurement Computing (MCC) recently introduced two product series targeted at low-cost DAQ applications. The USB-2408 Series features 24-bit devices with 16 voltage or eight thermocouple inputs, digital I/O, and optional analog output. They offer sample rates up to 1 kS/s. The USB-1608G Series of high-speed, multifunction devices includes 16 analog inputs, digital I/O, and optional analog output with sampling rates up to 500 kS/s.

The company also has been emphasizing software. Peter Anderson, general manager, said that emphasis is apparent in the DAQFlex products—USB devices that use a message-based protocol that eliminates the need for a separate driver. MCC posted a white paper about using DAQFlex Devices on tablets and created an open-source sample program for using these devices with an Android tablet.

Anderson said, “MCC’s focus is lowering the cost of DAQ systems—both in continuing to lower the cost of hardware and supporting new low-cost platforms.”¹ The MCC USB-1608G sells for $399, he said, more than 35% less than the cost of comparable devices. The USB-2408, he said, gives a similar shift in the price/performance curve.

Strain-Gage Support

UEI has introduced several new products including the DNx-AI-224, a four-channel, high-speed strain-gage input board; the DNx-IRIG-650, an IRIG and GPS timing interface; and the UEI-RSS Remote Serial Server Software for the company’s DNx-SL-501 and DNx-SL-508 serial cards.

Bob Judd, director of marketing, said, “The DNx-AI-224 was developed in response to requests from our existing DNx-AI-208 users. We took pretty much all the requests from our various customers and rolled them all into one board.” The new board, he said, is much faster and provides onboard anti-aliasing filters, bridge-completion resistors, automatic bridge nulling, and tension and compression shunt calibration.

Judd said the DNx-IRIG-650 was designed for customers who need enhanced sample timing capabilities. “We see two diverse yet popular applications for the IRIG board. The first is in flight-test applications where our system needs to coordinate sample timing with devices already on the aircraft. The IRIG interface is designed to do this. The second application is geological and seismic testing where people distribute the DAQ devices over a wide area but need to precisely coordinate sample timing across the system.”

In addition, Judd said, “Though we’ve all been predicting the death of RS-232 since I got into this industry in 1984, every report I’ve read indicates it is still by far the most common DAQ interface. We have many customers who need to interface a host PC to serial-based DAQ devices located large distances from the host PC. In these systems, our customers put a number of serial ports in one (or more) of our cubes, place the cube near the serial DAQ device, and then run an Ethernet (wire or fiber) back to the host PC. UEI-RSS makes those remote serial ports look just like a standard COM1 or COM2 in the host PC.”

That said, the company also offers support for a wide range of interconnects, including ICP/IEPE, RVDT/LVDT, synchro/resolver, CAN bus, RS-232/422/485, HDLC/SDLC, ARINC-429/708/453, and MIL-STD-1553. And the company’s products are compatible with many operating systems beyond Windows including Linux, QNX, VxWorks, and RTX.

High-Speed Acquisition

Microstar Laboratories recently introduced its xDAP7410 and xDAP7420, both aimed at 16-bit high-speed simultaneous sampling acquisition systems. Both units have a built-in 2.0-GHz processor that, combined with optimized hardware and software, enables the units to sustain 8 MS/s to a moderately powered Windows PC over USB, according to Ian Lewis, president. The built-in 1-GB data memory on the processor provides buffering for more than a full minute of data even at the maximum rate of 8 MS/s, he explained, simplifying PC application development.

Lewis noted that all the company’s systems include a built-in processor to manage acquisition hardware. That, he said, provides a consistent interface between user applications and hardware and allows a developer to preprocess raw acquisition data streams before sending them to the user interface application running under Windows.

“For example,” he said, “assuming you are using an xDAP7410 at full rate, you have a raw data stream of 8 MS/s. The xDAP7410 can easily sustain continuous transfer at this rate. But then your application needs to read the data and do something with them to keep up. Add a second unit, and you have twice that rate to deal with. Using onboard processing you can transform your samples from a raw data stream into an application-specific data stream. If you were working on impact testing, then you could use the built-in triggering support to only take data when signals exceed some threshold, indicating that an impact has occurred.”

Lewis said his company serves customers in three main application areas: industrial OEMs who develop machines on a Microstar platform to make complete application-specific products for their customers; university users who build custom experimental systems around Microstar products; and end users who make one-off purpose-built systems for industrial installation.

DAQ Applications

Some vendors target specific markets for their DAQ products. For example, iWorx, a developer of physiology research tools, has just introduced its IX-404E Data Acquisition System, which can be embedded in a variety of biomedical and analytical devices. The system features four single-ended analog inputs and a 16-bit ADC. The IX-404E comes with iWorx LabScribe2 Recording and Analysis Software.

The other vendors mentioned in this article, however, serve a variety of applications areas. Narayanan at VTI cited some specific examples: Boeing, he said, has used more than 9,000 channels of the EX1629 to perform structural tests on the 787 Dreamliner. In addition, he said, virtually all jet-engine manufacturers use VTI hardware for their DAQ needs. Renault, he added, uses VTI Instruments products to perform testing on their racecar engines, and Intel uses the EX1048A to perform thermal shock testing on its chips. In addition, aerospace companies like ATK Thiokol have used VTI’s DAQ products to perform rocket tests, and Vought, Messier Dowty, and others have performed landing-gear tests using the EX1629.

Grant at Dewetron said that major applications for Dewetron systems include vehicle testing, flight testing, energy testing, and industrial DAQ applications. The company’s capability to record more than just analog and digital signals is key to applications like these, he said.

“With Dewetron systems, you also can input up to eight video streams plus all manner of bus data,” including CAN bus data from cars, trucks, motorcycles, trains, and construction and military vehicles, Grant said. In addition, the systems can acquire ARINC and MIL-STD-1553 bus data from commercial and military aircraft as well as PCM encoded data from missiles and spacecraft. “All of these data streams are recorded in sync according to a high-resolution master clock that runs in the background, allowing everything to be displayed and recorded together,” he explained.

Pippert at Agilent said the 34970A/34972A have served in varied applications areas, including measurement of attenuation in a satellite communications channel during rain, measurement of humidity in storing and preservation of food grain, studies of wind direction and velocity for deciding where to erect windmills, and studies of power generated using wind energy.

In addition, she said, multiple DAQ units have been used for temperature profiling of a chemical reactor, adding that the DAQs also have been used to monitor differential temperature across a building wall in an effort to minimize air-conditioning requirements in tropical countries. Similarly, she said, 34980A has served “a variety of unique applications, most frequently environmental chamber monitoring and electronic functional test with data gathering and reporting.”

As for applications areas for NI DAQ hardware and software products, Delvizis said, “While aerospace and defense, laboratory/R&D, production test, scientific, and manufacturing applications are the most common, we also serve the long tail of unique applications.” Some such applications include monitoring plastic biodegradation with LabVIEW and NI CompactDAQ, capturing groundbreaking tornado phenomena using LabVIEW and NI CompactDAQ, and automated dynamometer testing of an in-wheel drive system for electric vehicles.

From Pumpkin Chunkin’ to Firefighting

The applications can range from the whimsical to deadly serious. In the former category, Anderson at MCC said one group used an MCC USB-2404-UI to monitor a catapult that won first place in the World Championship Pumpkin Chunkin charity games.² In the latter category, WHP Training Towers use the WLS-TC and WLS-IFC in a firefighter training product. The WLS-TC remotely monitors the interior of a structure that is lined with special thermal insulation to allow for repetitive training sessions.

Judd at UEI said his customers often prefer not to share their applications efforts with their competitors. However, he did confirm that UEI products have been used to control an astronaut exercise treadmill on the International Space Station and that one customer is about to deploy UEI products in well-head blow-out controllers 10,000 feet below the ocean surface. You can expect to see DAQ vendors continue to serve all points in between.