Since change is the rule—not the exception—in the electronics test industry, it’s not surprising that advice given three years ago has changed, too. When EE posed the question whether data acquisition software and hardware should be procured from the same source, the opinions were divided. Today, the market is different, and most PC-based data acquisition hardware providers offer a complete basic software environment to fulfill your needs—up to a point.
Up to a point, because the enhanced software mainly gets your hardware up and running quickly so it cannot, by itself, handle every configuration. Quick-installation software packages have a lot to offer and are more than adequate for most data acquisition applications. But, higher-level application builders still are needed for more complex tasks.
Load, Configure, Collect Data
In the typical PC-based data acquisition system-commissioning sequence, subsequent to interconnecting the hardware, you load the software, set equipment parameters, and verify operability. While these tasks took many hours in the past, the menu-based, fill-in-the-blanks, or graphical software accompanying today’s hardware often lets you complete the setup and configuration effort within minutes.
Now, most software packages accompanying data acquisition hardware perform many tasks automatically, provide a convenient user-interface, and offer a range of application-oriented features. For instance, the program may automatically identify the operating system version, initiate the appropriate installation process, detect all hardware, and let you set parameters and collect data.
A typical sequence of the hardware-related automated activities for IOtech’s data acquisition software was described by Douglas Pisciotta, applications engineering manager at the company. When a software program starts for the first time, it
attempts to communicate with the hardware. If it can’t, it prompts you for configuration information. After the hardware is detected, you can verify signal connections and start recording data immediately.
To simplify system expansion or modification, the software automatically recognizes and configures signal-conditioning or expansion options. For instance, if you add a strain gauge signal-conditioning card to an existing system, you select the card from a pull-down menu, and the software automatically registers it and establishes and verifies the connections, Mr. Pisciotta concluded.
Functional verification follows initial installation, and again, the accompanying software simplifies this task. Intelligent Instrumentation provides a free diagnostic/utility software program as a companion to its data acquisition hardware, according to Rob Winkler, product manager of data acquisition products. It is a Windows program which allows you to configure any or all of the hardware channels and supplies feedback on whether everything is functioning correctly.
A real-time operational display helps obtain instant feedback not only for the signal connections, but also for the quality of acquired data, appropriateness of settings, and the status of stream-to-disk activity, commented Roger Lockhart, vice president at Dataq Instruments. “We built a gap detector into our software that alerts you, in real time, when the computer or hard disk is unable to maintain the stream-to-disk rate that has been selected.”
Most of these software packages are turnkey solutions adequate for most basic acquisition applications. For instance, Quatech offers a package that supports analog and digital I/O and lets you configure parameters without any programming. You use menus and an icon-driven interface to set and select the number of channels, gain, sampling rate, auto-scaling, and input trigger mode. It automatically calibrates the equipment and begins acquiring data. Results can be displayed in a multi-channel mode as a table or as a strip chart, explained Kevin Kline, data acquisition product manager at the company.
Almost all programs provided with data acquisition hardware feature strip-chart scrolling facilities, and many let you display data in dial, gage, or bar-graph formats. The analysis capabilities vary, but all packages provide the gateways needed to transfer data to higher-level analysis and display-oriented programs.
Application Builders and Composite Environments
For applications that use multi-vendor hardware, are complex, or require a comprehensive test executive to sequence data collection and processing functions, higher-level programs such as Intelligent Instrumentation’s Visual Designer, National Instruments’ LabVIEW, CEC’s TestPoint, and Hewlett-Packard’s HP-VEE are available. While each of these application development environments offers an extensive set of features, they do not require conventional programming since they are all graphical or icon based.
In Intelligent Instrumentation’s diagrammatical development environment, applications are created by selecting blocks from a pull-down menu and wiring them together in the order of data flow. Block functions include a variety of I/O blocks, display blocks, user interfaces, and data-processing blocks. Also provided are blocks for file I/O, execution control, DDE, and serial and GPIB communications. To set parameters for any block, you double-click on its icon.
A multi-purpose data acquisition and virtual instrumentation program from National Instruments develops custom-applications including data capture, analysis, and display. Wizards simplify developing data acquisition applications.
“A solution wizard searches through the set of example programs so that you don’t have to start from scratch,” said Chad Chesney of National Instruments. “Examples for basic I/O tasks are included as well as examples for logging and streaming to disk and process control.
“With a channel wizard, you can assign a name to each channel and use it in your program to avoid confusion. You also can make per-channel analysis choices,” he concluded.
A graphical application development environment from Capital Equipment Corp. offers a high degree of automation. While the designer devises an application, the software creates a list of the required hardware, finds the initialization files, and scans the disk for the software drivers. When the driver is found, it is loaded and, if the hardware permits, the desired configuration is dynamically set and checked against the actual configuration.
All software objects representing hardware resources (A/D, D/A, digital I/O, GPIB) include pseudo-data sets that can be used in place of live data before hardware is available. Alternatively, the designer can create and insert custom test data.
These features are important because most software bugs occur at the boundary conditions, according to Sid Mayer at CEC. By creating test data that pushes the software beyond typical program executions, the designer can test for reliable operation at and beyond the software/hardware boundary.
Desirable and Essential Features
Although no two applications are alike, there is a minimum set of essential facilities that most require. These include:
A real-time data display in a chart or digital form.
The capability to save data, usually to disk.
Data quantification and processing facilities to access instantaneous/average/minimum/maximum amplitude and frequency values.
Time-and-date stamping.
The capability to view and process data after acquisition.
In addition, signal-analysis requirements often call for mathematical, fast Fourier transform, windowing, and digital filtering capabilities. Many programs include most of these features, and almost all convert the acquired pre-processed data into a standard format so that it can be exported to analytical programs such as The MathWork’s MatLab, Labtech’s NoteBook, DSP Development’s DaDisp, or HEM Data’s Snap-Master.
“Advanced post-processing capabilities often are indispensable,” said Fred Brown, product manager at HEM Data. “Being able to mathematically define the event you are looking for and use the results to intelligently apply special operations to specific data sets makes it possible to perform complex analysis.”
Depending on the application, a minimal or an extensive program linking capability also may be desirable. Report-generation facilities are almost always provided.
Reference
1. Jacob, G., “Software and Hardware from a Single Source?”, EE-Evaluation Engineering, May 1995, pp. 20-24.
NOTE: This article can be accessed on EE’s TestSite at www.nelsonpub.com/ee/. Select EE Archives and use the key word search.
Data Acquisition Products
32-Bit Software Yields Greater
Functionality, Compatibility
The 32-bit Hydra Logger Version 3.0 Software supports Windows® 95 and Windows™ NT applications. New telephone modem facilities use the standard 32-bit TAPI interface with plug-and-play compatibility and allow you to communicate with Hydra units in remote locations. Other enhancements include new tool and status bars, longer file names, batch-mode support for Trend Link, alarm status available through DDE, and recent file list in the setup menu. The complementing Trend Link software also is available in a 32-bit version. Hydra Logger 3.0: $595; Trend Link: $895. Fluke, (800) 44 FLUKE.
Application Generator Supports
Win 95/NT, Offers Enhancements
The Visual Designer Software is an application generator for PC-based data acquisition and control. It allows you to develop custom applications in the Windows® 95 and NT environments by drawing a block diagram rather than by coding the application with a programming language. Run-time customization features are provided. Visual Designer supports the company’s data acquisition hardware. A 32-bit Custom Block Toolkit allows you to add custom functions and create special hardware interfaces. Visual Designer: $695; Custom Block Toolkit: $495. Intelligent Instrumentation, (800) 685-9911.
Features Added to Integrated
Acquisition, Analysis Software
Snap-Master™ Version 3.2 is an integrated ensemble of data acquisition and analysis software for Windows® 95, Windows 3.1 and Windows for Workgroups. This latest version adds linked cursors, linked zooming, and new frequency-domain analysis with Intelligent Processing on FFT results. Intelligent Processing allows you to describe data of interest and lets Snap-Master locate the corresponding results, such as finding the frequency where a specific amplitude was reached. Drivers for the most common I/O hardware are provided at no charge. Data acquisition module: $995; waveform analyzer: $495; frequency analyzer: $495. HEM Data, (248) 559-5607.
Versatile Software Offers
Different Sample Rates/Channel
The new WinDaq/Pro+ and the WinDaq/Lite software for Windows record data acquired with the company’s DI-200 through DI-500 Series hardware products. WinDaq/Pro+ is an enhanced version of WinDaq/Pro that lets you select a different sample rate for each of up to 240 channels. WinDaq/Lite offers a 16-channel capability. The WinDaq Waveform Browser can review and analyze up to 254 waveform channels. It features seven cursor-based time/amplitude measurements, FFT, DFT, and 10 statistical analysis functions. Digital filtering allows graphical editing. WinDaq/Pro+: $1,995; WinDaq/Lite and WinDaq Waveform Browser: free. DATAQ Instruments, (800) 553-9006.
Instrument Software Features
Data Acquisition Wizards
Version 4.1 of the LabVIEW® graphical instrumentation software for Windows platforms features DAQ Wizards to streamline data acquisition through automatic, point-and click program generation. With the DAQ Solution Wizard, you describe an application by selecting from a list of common options, such as analog input, digital I/O, or file I/O. With the DAQ Channel Wizard, you fill in blanks to define the input signal, transducer type, and compensation, scaling, and unit-conversion factors. $995. National Instruments, (800) 258-7022.
Package Assures Seamless
Hardware/Software Operation
The DaqEZ™ Data Acquisition Application Software Package, compatible with Microsoft Windows 3.xx™ and Windows® 95, supports Quatech ISA and PCMCIA data acquisition boards (A/D, D/A, and digital I/O). No programming is required because you configure parameters and then record and display data. In combination with the DAQDRIVE® driver and hardware-configuration utility, DaqEZ also supports expansion, signal conditioning, and isolation adapters. Real-time data can be graphically displayed and stored for analysis. Waveform playback and analog output functions are provided. Price: Free with company’s data acquisition adapters. Quatech, (330) 434-3154.
Charting Software Lets You
Define 64 Display Groups
The ChartView™ charting software, included with the company’s ChartScan/1400 Recorder, is a recent addition to the line of Out-of-the-Box software packages. It enables you to configure systems, display waveforms, and stream data to disk without any programming. A built-in Chart Wizard allows setup of multiple display channels. It is compatible with Windows 3.x™, Windows® 95, and Windows™ NT. ChartView provides the trend and display capability of a chart recorder or logger and facilitates on-screen analysis. IOtech, (216) 439-4091.
Intranet Tools Add Flexibility
To Acquisition/Test Software
TestPoint™ is an object-oriented software tool for designing test, measurement, and data acquisition applications for Windows 3.x™, Windows® 95, and Windows™ NT. The new TestPoint Intranet/Internet Toolkit enables you to view results from any web browser, monitor and control tests remotely, and build client/server applications. With the TCP/IP object, you can construct remote-control panels to let TestPoint programs running on different computers communicate with each other. Applications can be activated and results or alarms can be sent via e-mail. TestPoint: $995; Intranet Toolkit: $395. Capital Equipment, (800) 234-4232.
Development Environment Offers
Fast Reaction, Processing Time
ADbasic Software is a 32-bit integrated development environment running under Windows 3.1x/95/NT to support the company’s ADwin Series plug-in boards for real-time data acquisition and control. ADbasic offers the ease of use of the BASIC syntax and generates binary code for ADwin microprocessors operating at optimal speed. Special commands allow direct access to all I/O and permit automatic data transfer between ADwin and the PC. $660. Keithley Instruments, (888) KEITHLEY.
Copyright 1998 Nelson Publishing Inc.
January 1998