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Software Add-Ons; A Low-Cost, Powerful Solution for PC-Based Data Acquisition

Steve Lekas, IOtech, Inc.
Adapted from an article that appeared in the April 1996 edition of ECN

Raw data is the foundation of any engineering project. Without it, hypotheses can be neither tested nor proved. The major tasks associated with data are acquisition, analysis, and reporting. Although time consuming, performing these tasks has become easier since the introduction of PC-based data acquisition systems.

Most engineers would agree that the backbone of any PC-based data acquisition system is the software that drives it. Unfortunately, easy-to-use data acquisition software has not always been readily available. As a result, engineers have had to write a specific program in a conventional language (Basic or C) or had to learn how to manipulate a dedicated icon-driven data acquisition package to acquire data. This can require a considerable amount of time. And, the tasks of analysis and documentation must still be performed, further increasing the demands on the engineer's time. Fortunately, a solution is at hand.

Multi-tasking environments, such as Microsoft's Windows® 95 and Windows™ NT, now provide powerful, low-cost data automation and acquisition software options--software component add-ons. Using software add-ons enables the engineer to easily integrate the setup and operation of data acquisition hardware with the tools needed to tabulate, analyze, graph, and visually represent and report data. Best of all, these data tasks can be effortlessly and seamlessly accomplished using existing software programs.

Defining the Software Components Concept

The term "software components" generally refers to software that can be added to or accessed from other software applications. To access or attach these software components, the developer must use an interapplication communication standard that is supported by all the components involved. Dynamic Data Exchange (DDE) and Object Linking and Embedding (OLE) are two common standards that are used.

By embedding or by adding software components together, users can easily customize general purpose software into a specialized application. In addition to saving an appreciable amount of time, this solution does not require engineers to write a single line of code or to glue together any icons.

A recent study indicated that more than 70 percent of engineers use a mainstream spreadsheet program, such as Excel™, to create data acquisition reports. It is easy to see why. Excel™ provides a wealth of basic functions that includes entering and editing data, building formulas to calculate values, and creating visual representations of worksheet data. In addition, it offers an assortment of high-powered math and analysis functions to perform tasks such as fast Fourier transforms (FFTs). Versions 5.0 and greater include functions that will retrieve and analyze data. These features make Excel™ an ideal choice for the software add-on concept.

Many software add-ons are available to expand the functionality of popular mainstream software applications. Spreadsheet software, such as Excel™, allows users to "add-on" additional functionality including specialized engineering analysis, statistical tools, and data-acquisition system control software. To "add-on" this expanded functionality, simply choose Excel's™ Add-in command from the Tools menu bar and select the check box of the desired Excel™ add-in (a new menu item will appear after selecting the check box). To use the "add-in," activate the add-in software icon in the Excel™ tool bar and the add-in's tool bar will be displayed.

Expanding Functionality via DaqViewXL™

IOtech has developed a new series of products to utilize the software component concept. DaqViewXL™, its first offering, is a data acquisition and display application add-in that seamlessly integrates data acquisition functionality into Micorosoft® Excel™. It features Windows™3.x and Windows® 95 compatibility, strip-chartlike graphics for real-time data display, and automatic conversion of data to engineering units.

Operating IOtech's Excel™ add-in is simple and straightforward. It does not require any programming; therefore, engineers do not have to write code, wire icons together, or build flow charts to collect data and place it in a spreadsheet. Once DaqViewXL™ is installed, the spreadsheet provides a floating tool bar that contains all the controls required to perform data acquisition. The tool bar, which is accessible from the Excel™ menu, allows complete configuration and execution of all data acquisition tasks. Acquired data is immediately placed in an active spreadsheet where it can be analyzed and graphically displayed.

DaqViewXL™ enables users to set up data acquisition applications directly from within Excel™. Using a simple graphical user interface (GUI), DaqViewXL™ provides access to all functions of IOtech's parallel port-based DaqBook®, plug-in DaqBoard™, and Daq PCMCIA card data acquisition products to configure this hardware for range, trigger condition, sampling rate, and signal conditioning. In addition to the set up controls, the GUI includes a spreadsheet-style channel configuration grid. Each column of this grid corresponds to specific parameters in the data acquisition system, allowing engineers to set parameters on a per-channel basis.

DaqViewXL's charting window provides real-time scrolling for a maximum of sixteen channels via a real-time strip-chart window. These graphic displays allow users to select the number of desired graphs and assign a channel to each. The enhanced charts scroll smoothly, while data is being collected from the specified channels at a maximum speed of 88 kHz. All sixteen charts are synchronized and feature an adjustable, deterministic scrolling speed that can be set independent of the sampling rate. All data collected is displayed, even at high sampling speeds, regardless of the scrolling rate.

DaqViewXL™ supports IOtech's entire line of DBK™ expansion and signal conditioning cards and modules. To add options, the user selects the desired signal conditioning in the Hardware Configuration Window. Once configured, DaqViewXL™ automatically provides access to new channels that can be individually enabled or disabled from the channel configuration grid. The engineering-unit outputs required by each DBK option are also provided by DaqViewXL™. When the mX+b feature is used, the collected data for a particular channel is automatically converted to custom units, scaled and offset, and placed in the spreadsheet.

Conclusion

Data acquisition, analysis and reporting can be greatly simplified and performed in a more time efficient manner by thorough use of the Software Components concept. For example, an engineer can embed an Excel™ spreadsheet object into a Word™ document. When the spreadsheet object is activated, it gives the engineer access to the DaqViewXL™ data acquisition add-in. An acquisition can be performed that updates the spreadsheet's calculated cells and dependent graph objects within a Word document. This powerful, compound document lets users collect, analyze, graph, and annotate their data all within a single document, with the click of a single button.

The Software Components concept is great news for engineers because it allows them to perform basic data tasks in a time-saving, simplified manner with software tools already in hand. And, as the computer industry migrates into the world of multi-tasking, software components are likely to emerge as the powerful, low-cost software solution for most data acquisition users.