Developing Algorithms Using LabVIEW MathScript: Part 1 – The LabVIEW MathScript Node

This series of documents provides exercises to inform you about NI LabVIEW MathScript. The below document offers a step-by-step example for using the LabVIEW MathScript Node to develop algorithms. The next document in this series explores the LabVIEW MathScript Interactive Window.

What Is LabVIEW MathScript?

With LabVIEW, you can choose the most effective syntax for developing algorithms, exploring signal processing concepts, or analyzing results. You can combine the LabVIEW graphical programming paradigm with LabVIEW MathScript, a math-oriented textual programming language that is generally compatible with the widely used .m file script syntax.

See Also:
Inside LabVIEW MathScript: Making LabVIEW Ideal for Textual Algorithm Development and Prototyping
Multimedia Demonstration of LabVIEW MathScript
Test-Drive LabVIEW MathScript

The LabVIEW MathScript Node

You can work with LabVIEW MathScript through either of two interfaces: the LabVIEW MathScript Interactive Window or the MathScript Node. Refer to Part 2 of this series for more information about the LabVIEW MathScript Interactive Window.

With the LabVIEW MathScript Node, the blue rectangular region on the figure below, you can run .m file scripts from your LabVIEW graphical programs (known as virtual instruments or VIs). You can use the MathScript Node to insert textual algorithms into a VI and then use the LabVIEW graphical programming environment to instrument the scripts by adding knobs, slides, buttons, graphics, and other user controls and indicators.

LabVIEW is a graphical development platform for engineering and science applications such as design, control, and test. In LabVIEW, you build a user interface, or the front panel, with controls and indicators. Controls are knobs, push buttons, dials, text entry fields, and other input mechanisms. Indicators are graphs, numerical displays, LEDs, and other output displays. After you build the user interface, you add code using VIs and structures to control the front panel objects. The block diagram contains this code.

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Complete the following steps to build the front panel and block diagram of a VI.

1. Launch LabVIEW.

2. From the LabVIEW Getting Started window, select File»New VI or click the Blank VI link to create a new VI.

 

 

3. On the front panel of the VI, select View»Controls Palette to display the Controls palette.

4. Move the cursor over the icons on the Modern palette to locate the Numeric palette. When you move the cursor over icons on the Controls palette, the name of the subpalette, control, or indicator appears in a tip strip below the icon.

5. Click the Numeric icon to display the Numeric palette.

6. Move the cursor over the icons on the Numeric palette to locate the Vertical Pointer Slide.

7. Click the Vertical Pointer Slide icon and drag it to the front panel.

 

8. Double-click the Slide label of the Vertical Pointer Slide. In the text box that appears, type Amplitude.

 

9. On the Controls palette, click the Modern link to return to the Modern top-level palette. Move the cursor over the icons on the Modern palette to locate the Graph palette.

10. Click the Graph icon to display the Graph palette.

11. Move the cursor over the icons on the Graph palette to locate the Waveform Graph. Click the Waveform Graph icon and drag it to the front panel. You can display the results of an application by using indicators, charts, and other graphical displays on the front panel of a VI.

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12. Select Window»Show Block Diagram to display the block diagram of the VI. Building a block diagram is similar to building a front panel. When you place objects on the front panel, LabVIEW creates terminals for those objects on the block diagram. You can wire data in or out of the block diagram terminals to display data on the user interface or to apply user input values in your application.

13. Find the Amplitude and Waveform Graph terminals on the block diagram.

14. Select File»Save As to save the VI.

Refer to the Getting Started with LabVIEW manual for more information about the LabVIEW graphical programming environment and the basic LabVIEW features you use to build data acquisition and instrument control applications.

See Also:
Getting Started with LabVIEW

Using the MathScript Node for Algorithm Development and Prototyping

You can use the MathScript Node to develop and prototype algorithms within LabVIEW. Complete the following steps to develop and prototype an algorithm in a MathScript Node. Run that script in the VI you created in the previous section.

1. On the block diagram, select View»Functions Palette to display the Functions palette.

2. Move the cursor over the icons on the Programming palette to locate the Structures palette.

3. Click the Structures icon to display the Structures palette.

4. Move the cursor over the icons on the Structures palette to locate the MathScript Node.

5. Click the MathScript Node icon.

6. On the block diagram, click and drag the mouse in a rectangular shape to place the MathScript Node.

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7. Click inside the MathScript Node and type the following commands.

x = linspace(0, 2*pi, 30);
b = A*sin(x)

Notice that the x = linspace(0, 2*pi, 30); command creates a new variable x and populates that variable with 30 samples evenly distributed between 0 and 2*pi.

(Optional) You also can right-click the MathScript Node and select Import from the shortcut menu to import an .m file script that you created.

8. Right-click the MathScript Node frame and select Add Input from the shortcut menu.

9. Type A in the input terminal to add an input for the A variable in the script.



10. Right-click the MathScript Node frame and select Add Output from the shortcut menu.

11. Type b in the output terminal to add an output for the b variable in the script.

12. Right-click the b output terminal and select Choose Data Type»1D-Array»DBL 1D from the shortcut menu to specify the data type of the b output variable.

 

13. Move the cursor over the arrow on the Amplitude terminal. The cursor becomes a wire spool, or the Wiring tool. Use the Wiring tool to wire objects together on the block diagram.

14. When the Wiring tool appears, click the arrow on the Amplitude terminal and then click the arrow on the A input of the MathScript Node to wire the two objects together. Data flows along this wire from the Amplitude terminal to the MathScript Node.

15. Similarly, wire the b output to the Waveform Graph terminal. You now can obtain appropriate data from the script and visually analyze the results with the rich user interface capabilities of LabVIEW. The block diagram should look like this:

16. Select Window»Show Front Panel to display the front panel of the VI.

17. Drag the slider of the Amplitude control to approximately 3.

18. Click the Run button, or the white arrow, at the top of the front panel. Notice that the waveform graph updates with a sine wave.

19. Drag the slider of the Amplitude control to a different value and run the VI again. Notice that the sine wave updates accordingly.

20. (Optional) Click the Run Continuously button, or the circular arrows, at the top of the front panel. Notice that the waveform graph updates each time you change the value of the Amplitude control.

21. Select File»Save to save the VI.

You can access the LabVIEW tools and functions through interactive palettes, dialog boxes, and menus. LabVIEW also provides hundreds of VIs that you can use within the programs that you create. Drag and drop these VIs onto a block diagram to define the behavior of the applications you write. This point-and-click approach significantly reduces the time you need to get from initial setup to a final solution.

Related Links

Developing Algorithms Using LabVIEW MathScript: Part 2 – The MathScript Interactive Window

 

Reader Comments | Submit a comment »

Great: Mathscript and other script nodes are a wonder weapon !
Mathscript Nodes and also the other script nodes are great. In shortest time i can implement my complex algorithm into Labview. That reduces development times dramatically! That really rocks !
- Geissler. aj.geissler@googlemail.com - Apr 16, 2008

For a keyboard person and procedural text type programmer who wanted a good mix between object at the front panel and scripts this is a pretty good page!
- Berns Buenaobra, IMI Design and Engineering. bernardino.j.buenaobra@imiphil.com - Mar 4, 2008

Very useful and essential guide! Thanks a lot!!
- Apr 17, 2007

this rocks man.
praise you! this has been most helpful!
- May 31, 2006

fig is not very clear
I know the figs are from snapshot of labview window, but there are not very clear, can't you make the same quality ?
- Jan 14, 2006

This rocks!!!
- Oct 21, 2005