1. Introduction to LabVIEW SignalExpress
LabVIEW SignalExpress is interactive, configuration-based measurement software with a drag-and-drop environment. You can use LabVIEW SignalExpress to perform common acquisition, analysis, and presentation tasks with stand-alone and modular instruments. You also can convert LabVIEW SignalExpress projects to LabVIEW graphical code and use LabVIEW to develop custom user interfaces, handle what-if or if-else scenarios, and perform analysis functions not available in LabVIEW SignalExpress.
Turning knobs and dials to perform measurements can be tedious, especially when you are performing a series of measurements or using multiple instruments in a system. With LabVIEW SignalExpress, you can communicate with and control stand-alone and modular PC-based instruments to automate measurement tasks such as frequency sweeps and limit testing. In addition, you can perform analysis while taking measurements to save time.
With LabVIEW SignalExpress, you can connect and control more than 300 different stand-alone instruments from multiple vendors as well as NI modular instruments.
NI modular instruments automatically install LabVIEW SignalExpress drivers when you install the device drivers. Please visit Drivers and Updates to download the latest drivers for modular instrument hardware. Supported NI modular instruments include:
- NI signal sources
- NI high-speed digital I/O
- NI digital multimeters (LCR Meter)
- NI switches
- NI DC power supplies
Table 1. Brief List of Stand-Alone Instruments Supported by LabVIEW SignalExpress
2. Controlling Instruments
Installing Instrument Drivers for Stand-Alone Instruments
The first step in connecting to and controlling instruments in LabVIEW SignalExpress is to download and install the IVI-C instrument driver for the instrument. These industry-standard instrument drivers provide advanced performance and interchangeability. LabVIEW SignalExpress offers a consistent interface for controlling each instrument type.
You can download all drivers for free from the NI Instrument Driver Network at ni.com/idnet. To find a driver on the network, select IVI from the Technology category (see Figure 1) and navigate to or search for the specific instrument model. From the instrument driver page, select the driver for LabVIEW to begin downloading the driver. When the download completes, run the executable file to install the driver.
Figure 1. Select IVI to view all available IVI drivers on the Instrument Driver Network
NI modular instruments install LabVIEW SignalExpress drivers when you install the device drivers. To update a driver, visit Drivers and Updates to download the latest drivers for modular instrument hardware.
Acquiring and Generating Signals from an Instrument
Once you install device drivers and connect the instrument to the PC, you are ready to take measurements in LabVIEW SignalExpress. To start a measurement, click the Add Step button to display the Add Step palette and select the appropriate step to acquire or generate a signal from the instrument.
Note: This application note focuses on connecting to and controlling an oscilloscope. The process for setting up other instrument types is very similar. Please refer to the LabVIEW SignalExpress Help for more information on controlling a specific instrument type.
To begin a measurement using an oscilloscope, select the IVI Scope Acquire step from the Acquire Signals-> IVI Acquire menu.
Figure 2. Adding the IVI Scope Acquire step to start acquiring data from an oscilloscope
Once you select the IVI Scope Acquire step, the Step Setup tab for the step appears. You then can select channels from which to acquire measurement data. Start by creating a connection to the instrument with a new IVI session. On the Configuration page of the Step Setup tab, find the IVI session name field and select Create New from the pull-down menu.
Figure 3. Creating a new IVI session
In the dialog box that appears (see Figure 3), select the instrument from the Resource descriptor pull-down menu and select the instrument driver from the instrument driver drop-down menu. Click the OK button to finalize the creation of the session.
To begin acquiring from the instrument, click the Run button on the LabVIEW SignalExpress toolbar. LabVIEW SignalExpress immediately connects to the instrument and begins showing its acquired data, live, on the screen. To configure the instrument, simply change any of the settings on the Step Setup window. As soon as you make a change, LabVIEW SignalExpress will immediately reconfigure the instrument.
3. Completing the Measurements
Viewing Data and Generating Reports
Along with viewing your measurements in the individual steps, LabVIEW SignalExpress has an interactive data view for viewing all of your acquired and analyzed data. To view a signal on the data view, simply click the Data View tab and drag and drop the desired data from the step on the left to the data view on the right. Customize the graphs by right-clicking on them and changing properties such as plot styles, colors, and axis labels. The graphs also provide zooming capabilities and the ability to add interactive cursors.
Figure 4. Viewing Data in LabVIEW SignalExpress
Along with the data view capability, LabVIEW SignalExpress offers a documentation view for creating custom reports. Create reports by dragging and dropping your measurement data onto the blank piece of paper and adding text. You can send custom reports to the printer or save them as HTML files for viewing in any Web browser.
Figure 5. Create Interactive Reports in LabVIEW SignalExpress
Signal Processing and Analysis
You can perform common analysis tasks with LabVIEW SignalExpress, including scalar math, time domain measurements such as amplitude measurements as well as frequency domain measurements such as distortion measurements and power spectrums.
To add analysis to your measurement projects, select the appropriate processing or analysis step from the Add Step menu. Once selected, the step loads and begins analyzing your acquired data.
Figure 6. Step Setup for the Power Spectrum Step
The simplest way to save your data is to press the Record button in the LabVIEW SignalExpress toolbar. This begins logging your measurements to disk using the highly optimized technical data management streaming (TDMS) file format. You can open TDMS files in all National Instruments software products as well as Microsoft Excel. You also can convert TDMS files to ASCII text for use in most third-party applications.
Along with streaming your measurements to disk, you can export your data to Microsoft Excel by right-clicking on any graph and selecting Export to Microsoft Excel. Additionally, you can just drag and drop your data into most third-party applications.
Figure 7. Drag and Drop data from LabVIEW SignalExpress into 3rd Party Applications
By saving your LabVIEW SignalExpress project you can avoid manually documenting instrument settings. LabVIEW SignalExpress projects save the instrument setting, and your analysis, logging and documentation configuration
You can use LabVIEW SignalExpress to perform your basic instrument control tasks interactively to save time. This including acquiring, analyzing and presenting your measurement results from more than 400 stand-alone and modular instruments.