Remember when companies had fully staffed departments dedicated to developing test systems and programs for you? Those days are gone. To stay competitive in today’s job market, you need to put your own test system together. Choosing the most appropriate data acquisition software for your application is critical to accomplishing this task.
The first steps toward finding a data acquisition software package that fits your application are understanding your current and future application requirements and determining the types of tasks you would like to be able to perform. These usually include one or more of the following:
Verifying signal connections.
Logging and streaming data to disk.
Monitoring real-time data.
Controlling a test or process.
Analyzing the acquired data.
Generating reports in a variety of graphical formats.
Designing turnkey applications that can be used by lesser-skilled operators.
Once you know what you need to accomplish, you can evaluate software.
Three Types of Data Acquisition Software
Most Windows-based data acquisition software can be grouped under one of these categories:
Software that provides instant results for dedicated functions such as datalogging and display.
Icon-based point-and-click software for interactively developing more advanced custom test applications.
Comprehensive programming environments that provide flexibility for creating complex algorithms and custom operator interfaces.
By understanding the differences among the three types of software, you can select a specific software package that performs the tasks and delivers the results that your application requires.
Instant-Results Data Acquisition and Display Software
Instant-results data acquisition software gives you immediate results. No matter how complex your application is, instant-results software can provide nearly effortless dedicated functions such as basic signal verification, real-time data display and datalogging. It lets you verify your signal connections, view your data as it is being acquired, and record it within minutes of connecting your hardware (Figure 1).
Some data acquisition system suppliers include instant-results-type data acquisition software free with their products. Other data acquisition vendors make such software available as an option, generally for less than $1,000. Examples of instant-results software packages include IOtech’s DaqView™, National Instruments’ VirtualBench™ and Scientific Software’s VisualSCOPE™.
Instant-results data acquisition software enables you to verify your signal connections within moments of connecting your data acquisition hardware. With this type of data acquisition software, you can quickly and easily configure your hardware and establish acquisition parameters without writing any code.
Some instant-results packages let you set up triggering, sampling rates, datalogging and direct-to-disk acquisition in a point-and-click environment. This type of software sometimes offers the capability to customize your data’s real-time display.
Graphical instant-results data acquisition software generally takes advantage of specific data acquisition hardware strengths, such as fast direct-to-disk speed and collection of multi-sensor, multi-gain inputs. Most graphical instant-results data acquisition software users have applications that primarily include datalogging tasks. Generally, they require data immediately and cannot wait to create a custom datalogging software application.
Examples of these types of datalogging tasks include recording the thermal conductivity of materials, monitoring temperatures over long periods of time, and recording the magnitude of pressure waves caused by the detonation of explosives. With an instant-results data acquisition program, you easily configure your hardware, collect data and then import the data into a software package such as Microsoft’s Excel™, MATLAB™ by The MathWorks or DSP Development’s DADiSP™ for data analysis and reporting.
For applications that only require hardware setup, data capture and real-time display, instant-results data acquisition software provides a complete solution. As your needs change or become more complex, you can always migrate to other software environments that offer more flexibility for creating custom advanced test applications.
Interactive Icon-Based Point-and-Click Data Acquisition and Control Software
Interactive icon-based data acquisition and control software packages have a means of configuring your data acquisition setup, display and analysis without the need to program. In fact, icon-based packages do not require programming. Examples of icon-based interactive software include DASYLab™ from DASYTEC and Snap-Master™ from HEM Data, all of which cost from $500 to $2,000 (Figure 2).
With one of these software packages, on a day-to-day or minute-to-minute basis, you can alter your application by connecting a few icons to collect, analyze and report your data. Icon-based data acquisition software packages offer a variety of data display formats, mathematical and statistical analysis functions, and reporting formats to meet the demands of your dynamic test environment.
Interactive icon-based data acquisition, control and analysis packages generally require little effort to learn. In contrast to programming environments, whose mastery often demands extensive formal instruction, interactive icon-based data acquisition software does not require you to write or understand programming constructs. Instead, it offers you a point-and-click GUI so you can build on-screen block diagrams via a series of functional icons.
Most interactive icon-based data acquisition software also has extensive configuration, importing, analysis, graphing, control and reporting capabilities, all of which can be configured via intuitive dialog boxes. A simple application takes minutes to complete.
Interactive icon-based packages differ from graphical programming environments because the former allows you to combine functional blocks that enable operations such as the acquisition and graphing of readings. The latter provides icons that represent programming constructs such as IF and WHILE statements.
Interactive icon-based data acquisition software permits you to acquire data from many sources. These include notebook and desktop PC-based data acquisition systems, signal conditioning and expansion options, and IEEE 488 and RS-232/422 data acquisition instruments from many data acquisition vendors—often in the same application.
Users who buy interactive icon-based data acquisition software typically work in an R&D environment, a test department or an academic setting. They tend to prefer an icon-based intuitive approach for collecting and viewing data because it requires little effort to learn.
Many like having an integrated tool to easily and quickly reconfigure their hardware and publish test results. Other users, such as those who teach or conduct research in university laboratories, find interactive icon-based data acquisition software ideal for quick setup of experiments in classroom applications.
Graphical Programming Environments
Some users have applications that require unique data acquisition and control capability which only they can generate. Once they have created their applications, they also may need to design a turnkey application suitable for use by a non-technical operator.
If you have such an application, a graphical programming environment may be right for you. It helps you to create demanding system requirements, such as algorithms and sophisticated graphical interfaces.
Obtaining a custom turnkey solution via graphical programming environments can be an expensive proposition because of the development time involved. Today, the leading graphical programming environments are Visual Basic™, which starts at $195 for the basic package; and LabVIEW™, which ranges from $1,000 to $2,000 (Figure 3).
Visual Basic, Microsoft’s rapid application development environment, has revolutionized programming by providing a simple, easy-to-use programming architecture. Visual Basic’s VBXs and OCXs third-party extensions can significantly reduce development time by letting you seamlessly construct data acquisition, control, data analysis and real-time display applications.
Visual Basic’s simple syntax and visual GUI-development tools make it ideal for both straightforward and sophisticated applications. It costs less than dedicated data acquisition programming environments. But more importantly, you can freely distribute your software applications without paying any royalties.
LabVIEW, National Instruments’ graphical data acquisition programming environment, enables users with a programming background to create complex data acquisition, control, analysis and display applications. You construct pictorial diagrams by selecting procedural icons from a specific icon library and connecting the icons on a virtual worksheet.
LabVIEW also requires you to develop a GUI that interacts with the pictorial program. It features a large selection of procedural icon libraries. Each procedural icon within a library represents a conventional programming construct (for example, FOR or WHILE) or a conditional statement (for example, IF) similar to those found in languages such as C or PASCAL.
Like Visual Basic, LabVIEW has particular operating parameters that you must master. National Instruments offers a three-day basic LabVIEW training class and training materials to help you get started. Users of graphical programming environments maintain that developing applications with LabVIEW is quicker than application development with conventional text-based programming languages.
Visual Basic and LabVIEW users often are involved in designing dedicated automated test systems. Usually, the test system must be designed so it can be operated by a non-technical person.
Conclusion
No single data acquisition software package can be all things to all users. Likewise, you may find that not all PC-based data acquisition hardware can provide you with exactly the functionality you require. By acquainting yourself with the basic types of data acquisition software available, you will be better able to choose the one that most appropriately suits your application.
Why spend a month developing a datalogging program when there is one already available off-the-shelf? With the wide array of choices available, you can choose hardware from virtually any data acquisition supplier.
You may also find that it makes sense to own more than one software package. You can start with an instant-results data acquisition package to configure your hardware and to verify your setup. Later, you can turn to a graphical programming environment to develop an application that can be used by an unskilled operator. This approach gives you the best of both worlds: ease of use and wide ranging functionality.
About the Author
Steve Lekas is the software marketing manager at IOtech. Formerly IOtech’s director of research and development, Lekas has more than 15 years experience in the test and measurement industry, and also has worked for Gould’s Recording Systems Division and Keithley Instruments. He holds B.S.E.E. and M.S.E.E. degrees. IOtech, 25971 Cannon Rd., Cleveland, OH 44146, (216) 439-4091.
Copyright 1996 Nelson Publishing Inc.
December 1996
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