NI LabVIEW is a graphical programming environment that makes it easy to take any measurement from any sensor on any PC bus. From taking a simple temperature measurement to capturing data from a complex 10,000-channel system, you can acquire data in less time with LabVIEW than traditional text-based programming languages.
A LabVIEW program is called a virtual instrument (VI). Each VI contains a front panel and a block diagram. The front panel functions as the user interface. On the front panel, you can place buttons, switches, graphs, tables, and more
Figure 1. The LabVIEW front panel is the user interface, which is fully customizable with buttons, knobs, graphs, and charts.
On the block diagram, you develop graphical code to acquire and analyze your measurement data, branch and repeat code, and interface with elements on the front panel.
Figure 2. On the LabVIEW block diagram, you create graphical code with nodes, wires, and loop structures.
Data acquisition applications usually involve acquiring signals, displaying data in a graph or chart on the front panel, and saving the data to a file. All of these elements are easy in LabVIEW, and there are several features for configuration and getting started.
All National Instruments data acquisition (DAQ) devices include Measurement & Automation Explorer (MAX), a configuration and test utility. You can use MAX to:
- Configure and test data acquisition hardware with interactive test panels
- Reference device pinouts and documentation
- Create virtual channels
MAX displays all of the data acquisition devices connected to your PC. In MAX, you can open a test panel for your device. With test panels, you can verify that your signal is connected properly and visualize its values in real time (see Figure 3).
Figure 3. With MAX test panels, you can test data acquisition device functionality and verify signal connections.
In MAX, you can right-click on your data acquisition device, select “Device Pinouts,” and immediately view the terminals that correspond to the analog, digital and counter channels on your device (see Figure 4).
Figure 4. MAX gives you quick access to your device pinouts.
In MAX, you can set up virtual channels that map configuration information, such as scaling and input limits, to a specific physical channel on your device. There are multiple virtual channel measurement types, including pressure, force, and torque (see Figure 5). By using a virtual channel, you can quickly convert raw voltages into engineering units such as Newtons or pounds per square inch.
Figure 5. You can use MAX to set up a virtual channel to establish parameters such as scaling, input limits, and engineering units.
2. NI-DAQmx Driver Software
All NI data acquisition devices include NI-DAQmx, a comprehensive hardware driver that features the DAQ Assistant and a low-level application programming interface (API).
You can use the DAQ Assistant, a dialog-based wizard accessible from MAX or LabVIEW, to create virtual channels and measurement tasks without programming.
Figure 6. The DAQ Assistant helps you quickly acquire or generate data without programming.
While the DAQ Assistant provides a quick and easy way to acquire or generate data without programming, more advanced users may need added flexibility and lower-level control than what the DAQ Assistant offers. The NI-DAQmx driver features a comprehensive API of basic and advanced functions for control over such parameters as timing, synchronization, data manipulation, and execution control (see Figure 7).
Figure 7. You can use the NI-DAQmx API to specify advanced parameters such as triggering and synchronization.
3. Front Panel Customization
With LabVIEW, you can quickly create a graphical user interface with hundreds of included drag-and-drop controls, graphs, and 3D visualization tools. You can customize the position, size, alignment, scale, and color of these built-in controls in a matter of seconds from a right-click menu.
Figure 8. With the LabVIEW front panel, you easily can create custom user interfaces with included charts, knobs, and buttons.
Figure 8 shows two controls – Number of Measurements and Delay (sec) – and one indicator, a waveform graph named Temperature Graph. You can change the input value for the Number of Measurements and Delay (sec) controls, and see the values generated by the VI on the Temperature Graph indicator. The VI generates the values for the indicator based on the code created on the block diagram.
In LabVIEW, you can completely customize the look of your front panel with custom controls, imagery, and decorations (see Figure 9).
Figure 9. Advanced users can completely customize the look and feel of the LabVIEW front panel.
4. Example Finder and Community
LabVIEW includes hundreds of example VIs to help you get started with your data acquisition application. You can search for examples using the LabVIEW Example Finder (see Figure 10).
Figure 10. The LabVIEW Example Finder contains hundreds of application- and industry-specific example VIs.
NI Developer Zone Community
In the NI Developer Zone community, you can collaborate on the latest example code, tutorials, textbooks, and more with a worldwide community of engineers and scientists. You can share development techniques, learn about the latest technologies, and connect with LabVIEW and other NI product experts working on similar applications. Visit the community at ni.com/community.
5. The Easiest Way to Acquire, Analyze, and Log Data
LabVIEW 2011 is the easiest and most flexible method to acquire measurement data, analyze it, and log your data to disk. With included tools like MAX, NI-DAQmx, and the LabVIEW Example Finder, you can get started quickly and customize your application as your system and requirements evolve over time.
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