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Data Acquisition Application Development Software --Something for Everyone Whether you want programming muscle or no programming at all, ActiveX support Glenn Hartwig There are many application development packages that can help you design your own data acquisition (DA) programs. They range from those that require no programming experience to some that have features more in common with traditional programming languages, from general-purpose packages to tightly integrated, modular add-ons. All the packages tend to be feature rich, and many are similarly constructed. Oftentimes, the differences among the packages are a matter of emphasis (i.e., the things the vendor feels are most important to include in the software), and that in turn depends on what users tell the vendor they would like to see. Many of the development packages are drifting away from the concept of one person-one machine, leaving behind the image of the solitary engineer or technician gathering data in the lonely environment of the workbench. More and more, networking (both local area data sharing and wider area internetworking) is becoming a common theme in DA. In this regard, such features as ActiveX controls, Java support, HTML publishing tools to automate data presentation on the Internet, and such office automation tools as report generation and presentation are taking a larger share of the spotlight. Ease of use--always a subject of discussion between the forces that want quick results and those that want highly customized DA programs--is still a hot topic. One school promotes the increased use of preprogrammed modules, which are proliferating as fast as the vendors can identify a need and produce something that provides the desired functionality. The other school claims that the way to handle specialized requirements is to give users the tools they need to easily program their own customized measurement modules. Regardless of which side you find yourself on, the common thread seems to be the desire for a more accessible development environment, one that features increased use of GUIs, drag-and-drop component insertion, easier program creation, and more powerful graphing and display functions. Individual packages also differentiate themselves by emphasizing such features as real-time capabilities or broad compatibility with industry hardware. The trend, as with all things relating to computers, is toward faster, less expensive, and more reliable products that offer networking. Modular Approaches From the perspective of Sid Mayer, president of Capital Equipment Corp. (Billerica, Massachusetts), "Our TestPoint product is aimed at the general engineering audience. It is a general-purpose tool for building data acquisition and test and measurement applications. It has the power of a programming language in terms of its capabilities, but it is designed to be accessible to someone whose expertise is not programming." With this in mind, TestPoint relies on graphical windows as an overlay for the behind-the-scenes code. Capital Equipment also offers a selection of add-on modules for TestPoint that perform specialized functions. For example, the Internet Toolkit provides remote monitoring and control, includes a Web server, and lets you publish the measurements of Web-enabled applications on the Internet. The Database Toolkit provides access to popular database packages--whether they are on a PC, server, or mainframe--and supports all SQL operations to let you organize, file, update, and retrieve information from DA applications. A toolkit for statistical process control, automatically derives control limits from process data, identifies problem areas that need improvement, tests for trends, and gathers statistics. The company is also introducing OPC support to aid connectivity between its product, factory automation buses, and factory management and process software. Additional enhancements have included the addition of ActiveX controls, the ability to call 32-bit DLLs, and Windows NT compatibility. Ease of Use C.J. Butler, North American Sales Director of DASYTEC USA, Inc., (Amherst, New Hampshire) says that DASYLab customers particularly like the software's ease of use. "Most of our users are not programmers," she says. She notes that, "DASYLab doesn't present you with the low level of abstraction that other packages employ. Our simplest setup is an A/D input and a chart recorder. All you have to know is that if you put these two function blocks on your screen, hook them up, and hit the start button, you'll see data marching across your chart recorder." She comments that her company's goal is to produce software that deals with the lower levels of programming abstraction so the user doesn't have to. "We find that most of our users don't want to spend a lot of time programming or setting up, and they're willing to trade some customization capability for ease of use."
On the other hand, Butler knows that individuals will sometimes have no choice but to create their own low-level code. To handle these requirements, the company created the Extensions Toolkit, which lets you extend the basic program by designing your own module classes in the C programming language. Also, DASYLab produces a Driver Toolkit, which lets application developers program drivers for DA devices. As for the enhancements called for by program developers, Butler says, "We're seeing more requests for multiple computer support--in other words, networking. We have a network feature now and can support DASYLab-to-DASYLab quite successfully." The company is also in the process of adding DataSocket technology, she says, which will permit networking with most National Instruments boards, and it should also support OPC. "We also support DDE and net DDE, which also gives you interprocess communication," says Butler. On the other hand, programming such features as ActiveX and multithreading are not specifically accessible to the user "because they're not necessary in our environment. In the DASYLab context, we take care of the low-level programming features, and the user runs our program as an application. We handle those capabilities, but we don't put them out there where the user can see them." Real-Time Performance Microstar Laboratories, Inc., (Bellevue, Washington) slices the market a different way. Says George Atherton, Microstar's Marketing Manager, "Our product [DapView for Windows] is a real-time, multitasking system. We focus on the time-critical aspects of an application." The Microstar product is designed to work as a module that functions with other DA applications development programs--such as LabVIEW, HP VEE, and DASYLab--with special emphasis on, "doing all the real-time work," says Atherton. Applications that can use such real-time capability, he says, are typically ones that send out a control signal based on the acquired data. Additionally, data collection that requires sampling before, during, and after a short duration event (e.g., crash testing) can benefit from the high-speed DA capabilities of DapView. Actual programming in DapView for Windows depends on the user's preference, according to company president, Neil Fenichel. "Our customers cover the full range," he says. "We can talk about programming with icons, all the way to programming languages." Aside from DapView for Windows, Microstar also produces an application programming package called DAPtools. This software provides the drivers and interface software necessary to work in a 32-bit Windows environment. It includes a local DAP server for Win32, called Accel32; DAPview for Windows; DAPtools OCX, which is OLE control for Visual Basic; and other ActiveX containers, as well as having specially designed interface modules for LabVIEW, HP VEE32, and MATLAB. DAPtools also includes FGEN for Windows, a program you use to create digital filters and to plot filter response as dB vs. frequency and as amplitude vs. frequency. A second version of DAPtools, called DAPtools Professional, contains all these features plus DAPcell Software for network use and Developer's Toolkit for DAPL for custom command development by experienced programmers. Broad Appeal
National Instruments (Austin, Texas) offers a variety of application development products for DA, providing ease of use and bare-knuckles programming. Its best-known DA software development package is LabVIEW (see Screen 1), which has a host of new features in version 5.1, including built-in Web tools, ActiveX technologies, new DLLs to help create smaller executables, and DataSocket technology to share data with other Internet-enabled applications. According to Tamra Kerns, Strategic Marketing Manager, "The traditional audience for LabVIEW is engineers and scientists rather than programmers. On the other hand, the other large package we have is LabWindows CVI, which is an interactive C development environment for building data acquisition applications. In that case, the users are C programmers." "We have found that there are three elements essential in a data acquisition application. The first is the acquisition itself. The second is data analysis. And the third is data presentation." According to Kerns,"it is this third aspect of the application that has been the focus of much on-going development at National Instruments. "Increasingly, we find more and more people want to present their data over the Internet," she says. Additionally, a National Instruments' DA program called Measure is an Excel add-on that lets you collect data from a spreadsheet and then display the information. "We also have an add-in tool called ComponentWorks, which lets you perform acquisition, analysis, and presentation in Visual Basic," says Kerns. "We have a wide spectrum, depending on the sophistication of the user and the complexity of the application they're trying to build," she says. One aspect to note about National Instruments packages is that they have cross-platform capabilities. LabVIEW was first introduced for the Macintosh and is now available for PCs, Sun workstations, and HP UX workstations. There is even a version available for use in the Linux operating system. Programming Is Good for You HP VEE is a DA application development product from Hewlett-Packard tailored more for the professional programmer than some of the other software packages mentioned (see Screen 2, page 91). According to Greg Goebel, support engineer for Hewlett-Packard in Loveland, Colorado. "It requires a knowledge of Basic programming constructs, but you don't have to be a C programmer. If you can program in Basic, you can program in VEE." Granted, a little fundamental programming isn't difficult, but this still represents a different basic philosophy than the school that claims it's wrong to make engineers become programmers just so they can gather data. The advantage of doing low-level programming is that you can fine tune your DA application program until it performs exactly as you want it to. On the other hand, HP VEE does share some features with products already mentioned, such as a built-in Web server and ActiveX support. It comes in versions for both Windows and HP UX and has a graphical programming environment. It's user interface is icon-based, but according to Goebel, "We have a fair set of user interface tools, but not 3D graphs. We can obtain them through ActiveX controls and ActiveX automation but that particular capability is not in VEE." Combination Shot
Rick Walter, President of HEM Data Corp. (Southfield, Michigan), points out that his company's product, Snap-Master, represents the engineer-not-the-programmer school. "We're trying to do as much as possible without programming." In spite of that, Snap-Master does offer a programmer's toolkit. For example, Snap-Master's Front Panel Library provides tools and example source code to program custom human interfaces in Visual Basic or C/C++. "We work with icons, but we try to minimize their use," says Walter. He points out that, instead of representing each detail of a program (i.e., discreet actions) with its own icon, the graphical model used by Snap-Master uses one icon to represent whole functions. "If you have sensors, you just drag out the sensor icon. If you have three A/D converters, you drag out three A/Ds. You're not doing it on a per-channel basis; you're doing it on overall functionality." Snap-Master also uses real-time graphics and a standard Windows GUI, provides multiple hardware manufacturer support, can accomplish simultaneous low- and high-speed DA, and has customized instrument capability. Focused Approach The Data Acquisition Toolbox for MATLAB, from The MathWorks, Inc., (Natick, Massachusetts) is designed to provide direct access to live measurement data from the company's MATLAB software package (see Screen 3). MATLAB is a specialized program for people who are designing and modeling systems or developing algorithms. The toolbox lets you control and communicate with a variety of off-the-shelf, PC-compatible DA hardware. "MATLAB is the base product, and the Data Acquisition Toolbox is one of a number of products that sit on top of it," says Loren Dean, Product Development Manager. The toolbox is a set of M-file and MEX-file functions that you execute from a command line or from MATLAB programs. It's tightly integrated with MATLAB rather than being a general-purpose tool for DA application development. As such, users who already have MATLAB can analyze or visualize their data while they're collecting it, save data for post-processing, and use collected data to make iterative updates of their test results based on their analysis results. Because the toolbox and MATLAB are designed to work together, it often becomes a chicken-and-egg type of question when trying to assign the location of specific features. For instance, Dean points out that ActiveX support is incorporated in MATLAB, but because you have to use MATLAB to use the Data Acquisition Toolbox, you could just as easily say that the toolbox supports ActiveX controls. It may not even be important to make such distinctions because the toolbox is not a stand-alone product and the net result is the same. Still, you need to be aware that the DA application development program is a module that works with another independent, program. This modular approach is a feature of several other offerings from The MathWorks. The company also has a MATLAB Web server, signal processing toolbox, and report generator, all of which are designed--like the Data Acquisition Toolbox--to work with MATLAB as the base product. For the General Practitioner Back in the area of general-purpose DA application development packages, American Advantech (Cincinnati, Ohio) produces VisiDAQ. Designed as an all-around application builder for DA, control, analysis, and presentation, VisiDAQ 3.1 is a Windows-based program that features a Visual Basic programming environment. It provides numerous graphical control and display icons that you drag and drop onto the screen to build the type of application you want. The company emphasizes that not only can you implement most DA and control systems this way, but the development process is also very rapid. Features include compatibility with Windows 3.1 and 95; an open real-time data center (Advantech's drag-and-drop, dynamic display of process data); the ability to script programs in Visual Basic; the ability to perform multiple monitoring and control tasks; object-oriented graphics; graphical icon (drag-and-drop) programming; configurable report design; real-time display, calculation, and control; real-time and historical trending; password protection; alarm/ event handling; DDE; OLE automation; user defined DLLs; and the ability to communicate via LANs. Take Your Pick The package you wind up choosing will depend on how complex your needs are, how fast you have to get up and running, whether you must create new applications frequently, how widely you have to share your results, and a host of other considerations. What's striking about the current crop of DA application development programs is the high degree of certainty that, no matter what your application requirements happen to be, there's something out there that will suit you to a T.
Glenn Hartwig is a freelance editor. You can contact him at glenn@top.monad.net
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