1. Diego Torres LabVIEW Student Ambassador Fall 2011 ITESM CQ
LabVIEW Workshop #1
Diego Torres
LabVIEW Student Ambassador
Fall 2011
ITESM CQ

2. Laboratory Virtual Instrumentation Engineering Workbench
What is LabVIEW?
Laboratory Virtual Instrumentation Engineering Workbench
What is NI LabVIEW? LabVIEW is a highly productive graphical development environment with the performance and flexibility of a programming language, as well as high-level functionality and configuration utilities designed specifically for measurement and automation applications.
In general-purpose programming languages, the code is as much of a concern as the application. You must pay close attention to the syntax (commas, periods, semicolons, square brackets, curly brackets, round brackets, etc.). In contrast, with LabVIEW you use icons to represent functions, and you wire them together to determine the flow of data through your program, similar to creating flowcharts. It has all the breadth and depth of a general-purpose programming language, but it is easy to use, increasing your productivity by decreasing the time required to develop your applications.
You can easily divide measurement and automation application into three main parts: acquisition, analysis, and presentation of data. LabVIEW provides a seamless way to acquire your data, perform necessary analysis on that data, and present the information in a chosen format. Throughout the seminar, we touch upon each of these three components of a measurement and automation application.
Each program in LabVIEW is called a virtual instrument, or VI. The VI serves as the primary building block of a LabVIEW application, and you can use it to modularize your code for efficient design, clear and concise documentation, and simplified maintenance. Each LabVIEW VI is made up of three main components: the Front Panel, Block Diagram, and the Palettes.
In the coming slides, we continue our discussion of the actual development environment of LabVIEW.
Compiled graphical development environment
Development time reduction of four to ten times
Tools to acquire, analyze, and present your data
© National Instruments Corporation LabVIEW Graphical Development Hands-On Seminar

3. Navigating LabVIEW Virtual Instruments (VIs) Parts of a VI
Starting a VI
Project Explorer
Front Panel
Block Diagram
Searching for Controls, VIs and Functions
Selecting a Tool
Dataflow
Polymorphism
~2.5 hours spent on this lesson, including exercises. This lesson is an introduction to navigating LV; you will later cover implementation.

4. A. Virtual Instruments (VIs)
Virtual Instrument (VI) – A LabVIEW program
The appearance and operation of VIs imitate physical instruments, such as oscilloscopes and digital multimeters.

5. B. Parts of a VI
LabVIEW VIs contain three main components: 1. Front Panel 2. Block Diagram 3. Icon/Connector Pane

6. B. Parts of a VI – Front Panel
Front Panel – User interface for the VI
You build the front panel with controls (inputs) and indicators (outputs)

7. B. Parts of a VI – Block Diagram
Block Diagram – Contains the graphical source code
Front panel objects appear as terminals on the block diagram

8. B. Parts of a VI – Icon/Connector Pane
Icon: graphical representation of a VI
Connector Pane: map of the inputs and outputs of a VI
Icons and connector panes are necessary to use a VI as a subVI
A subVI is a VI that is inside of another VI
Similar to a function in a text-based programming language
Icon Connector Pane

9. C. Starting a VI
Demonstrate using the Getting Started dialog box and the New dialog box to start a VI.

10. D. Project Explorer Use LabVIEW Projects to:
Group LabVIEW files and non-LabVIEW files
Create build specifications
Deploy or download files to targets
LabVIEW project files (.lvproj) include:
- references to files in the project
- configuration information
- build information
- deployment information
- etc
Use the Project Explorer window to create and edit LabVIEW projects
Select File»New Project
to display the Project
Explorer window
You also can select Project»New Project or
select Empty Project in the New dialog box to display the Project Explorer window

11. Using the Project Explorer
Demonstrate creating a project, adding files, and removing files.

12. E. Front Panel – Controls Palette
Contains the controls and indicators you use to create the front panel
Access from the front panel by selecting View»Controls Palette

13. E. Front Panel – Front Panel Toolbar

14. E. Front Panel – Controls & Indicators
Knobs, push buttons, dials, and other input devices
Simulate instrument input devices and supply data to the block diagram of the VI
Indicators
Graphs, LEDs, and other displays
Simulate instrument output devices and display data the block diagram acquires or generates

15. E. Front Panel – Numeric Controls/Indicators
The numeric data type can represent numbers of various types, such as integer or real
Numeric Control
Increment/Decrement Buttons
Numeric Indicator

16. E. Front Panel – Boolean Controls/Indicators
The Boolean data type represents data that only has two parts, such as True and False or On and Off
Use Boolean controls and indicators to enter and display Boolean (True or False) values
Boolean objects simulate switches, push buttons, and LEDs
Boolean
Control
Boolean
Indicator

17. E. Front Panel – Strings
The string data type is a sequence of ASCII characters
Use string controls to receive text from the user such as a password or user name
Use string indicators to display text to the user

18. LabVIEW Data Types – Terminals
Terminals visually communicate information about the data type represented

19. LabVIEW Data Types – Numerics
The numeric data type represents numbers of various types
To change the representation of a numeric, right-click the control, indicator, or constant, and select Representation from the shortcut menu

20. LabVIEW Data Types – Boolean
Behavior of Boolean controls is specified by the mechanical action
In LabVIEW, the Boolean data type is represented with the color green

21. Mechanical Action of Booleans
Use the Mechanical Action of Booleans VI located in the NI Example Finder to learn about the different switch and latch actions.

22. Data Types – String
A sequence of displayable or non-displayable ASCII characters
On the front panel, strings appear as tables, text entry boxes, and labels
Change the display type from the short-cut menu: Normal, ‘\’ Codes, Password and Hex
Edit and manipulate strings with the String functions on the block diagram
In LabVIEW, the string data type is represented with the color pink

23. Data Types – Enum
An enum represents a pair of values, a string and a numeric, where the enum can be one of a defined list of values

24. Data Types – Enum Enum: enumerated control, constant, or indicator
Enums are useful because it is easier to manipulate numbers than strings on the block diagram

25. Data Types – Dynamic
Stores the information generated or acquired by an Express VI
Non-Express VIs do not accept the dynamic data type
To use a built-in VI or function to analyze or process the dynamic data type, you must convert the data type
Numeric, waveform, or Boolean data indicators or inputs automatically convert the dynamic data type when wired
In LabVIEW, the dynamic data type is represented with the color dark blue

26. E. Front Panel – Shortcut Menus
All LabVIEW objects have associated shortcut menus
As you create a VI, use the shortcut menu items to change the look or behavior of front panel and block diagram objects
To access the shortcut menu, right-click the object

27. E. Front Panel – Property Dialog Box
Right-click a front panel object and select Properties to display
The options available on the property dialog box are similar to the options available on the shortcut menu for that object

28. E. Front Panel – Configure Multiple Objects
Select multiple objects to simultaneously configure shared properties

29. F. Block Diagram Terminals SubVIs Functions Constants Structures Wires
Block diagram objects include the following:
Terminals
SubVIs
Functions
Constants
Structures
Wires

30. F. Block Diagram – Functions Palette
Contains the VIs, functions, and constants you use to create the block diagram

31. F. Block Diagram – Block Diagram Toolbar

32. F. Block Diagram – Terminals
Terminals are:
Block diagram appearance of front panel objects
Entry and exit ports that exchange information between the front panel and block diagram
Analogous to parameters and constants in text-based programming languages
Change the view type of a terminal by toggling the View as Icon selection from the context menu

33. F. Block Diagram Terminals

34. F. Block Diagram – Nodes
Objects on the block diagram that have inputs and/or outputs and perform operations when a VI runs
Analogous to statements, operators, functions, and subroutines in text-based programming languages
Nodes can be functions, subVIs, or structures
Nodes

35. F. Block Diagram – Function Nodes
Fundamental operating elements of LabVIEW
Do not have front panels or block diagrams, but do have connector panes
Double-clicking a function only selects the function – does not open it like a VI
Has a pale yellow background on its icon

36. F. Block Diagram – SubVI Nodes
SubVI: VIs that you build to use inside of another VI
Any VI has the potential to be used as a subVI
When you double-click a subVI on the block diagram, you can view the front panel and block diagram of the subVI
The upper right corner of the front panel and block diagram displays the icon for the current VI
This is the icon that appears when you place the VI on a block diagram as a subVI

37. F. Block Diagram – SubVI Nodes
Express VIs are a special type of subVI
Require minimal wiring because you configure them with dialog boxes
Save the configuration of an Express VI as a subVI
Icons for Express VIs appear on the block diagram as icons surrounded by a blue field

38. F. Block Diagram – Icons/Expandable Nodes

39. F. Block Diagram – Wires
Transfer data between block diagram objects through wires
Wires are different colors, styles, and thicknesses, depending on their data types
A broken wire appears as a dashed black line with a red X in the middle
DBL Numeric Integer Numeric String
Scalar
1D Array
2D Array

40. F. Block Diagram – Wiring Tips
Press <Ctrl>-B to delete all broken wires
Right-click and select Clean Up Wire to reroute the wire

41. F. Block Diagram – Wiring Tips
Use the Clean Up Diagram tool to reroute multiple wires and objects to improve readability
Select a section of your block diagram
Click the Clean Up Diagram button on the block diagram toolbar

42. Exercise 2-1 Concept: Exploring a VI
Identify the parts of an existing VI.

43. Exercise 2-1 Concept: Exploring a VI
What are constants and when should you use them?
What are free labels and when should you use them?
What are constants and when should you use them?
Constants are terminals on the block diagram that supply fixed data values to the block diagram. Use constants when your VI needs to use the same value every time the VI runs.
What are the free labels and when should you use them?
Free labels are not attached to any object, and you can create, move, rotate, or delete them independently. Use them to add comments to front panels and block diagrams. Free labels are useful for documenting code on the block diagram and for listing user instructions on the front panel. Double-click an open space or use the Labeling tool to create free labels or to edit either type of label.
Note: Constants and free labels have not been discussed yet, so now is a good time to briefly describe them and their purposes.

44. G. Searching for Controls, VIs & Functions
Find controls, functions, and VIs using the Search button on the Controls and Functions palette.

45. G. Global Search
The Search bar in the top right of the Front Panel and Block Diagram windows can be used to search the palettes, help, and ni.com.
New feature in LabVIEW Searches the local Help files and palettes as you type and if you press enter it will also search community and ni.com.

46. Exercise 2-2 Concept: Navigating Palettes
Learn to use the palettes and search for controls, functions and VIs.

47. Exercise 2-2 Concept: Navigating Palettes
Why would you want to add a function to the Favorites category in the Functions palette?
Why would you want to add a function to the Favorites category in the Functions palette?
You can put commonly-used functions in an easy-to-access category.

48. H. Selecting A Tool
Create, modify, and debug VIs using the tools provided by LabVIEW
A tool is a special operating mode of the mouse cursor
The operating mode of the cursor corresponds to the icon of the tool selected
When using the Automatic Tool Selection, LabVIEW chooses which tool to select based on the current location of the mouse

49. Exercise 2-3 Concept: Selecting A Tool
Gain experience using the Automatic Tool Selection to select which tool to use.

50. Exercise 2-3 Concept: Selecting A Tool
How do you enable automatic tool selection?
How do you enable automatic tool selection?
Make sure that the Automatic Tool Selection button is enabled on the Tools Palette. To view the Tools Palette, you can either select View»Tools Palette or hold Shift while right-clicking.

51. I. Dataflow LabVIEW follows a dataflow model for running VIs
A node executes only when data are available at all of its input terminals
A node supplies data to the output terminals only when the node finishes execution
LabVIEW is NOT control flow. Visual Basic, C++, JAVA, and most other text-based programming languages follow a control flow model of program execution.
Sequential order of program elements determines execution order.
LabVIEW follows a dataflow model for running VIs.
A block diagram node executes when it receives all required inputs.
When a node executes, it produces output data and passes the data to the next node in the dataflow path.
The movement of data through the nodes determines the execution order of the VIs and functions on the block diagram.

52. I. Dataflow – Quiz Which node executes first? Add Subtract
Random Number
Divide
Sine
There is no right answer to this quiz, but there are some wrong answers. This quiz is intended to encourage students to think about dataflow and its implications...

53. I. Dataflow – Quiz Answers
NO CORRECT ANSWER
Which node executes first?
Add – possibly
Subtract – definitely not
Random Number – possibly
Divide – possibly
Sine – definitely not

54. Exercise 2-4 Concept: Dataflow
Understand how dataflow determines the execution order in a VI.

55. Exercise 2-4 Concept: Dataflow
Should a well-designed block diagram flow in a particular direction?
Should a well-designed block diagram flow in a particular direction?
Yes, a well-designed block diagram typically flows from left to right. This makes it easier to see the flow of data on the block diagram.

56. J. Polymorphism
Definition: a programming language feature that allows values of different data types to be handled using a uniform interface.
In LabVIEW: the ability of VIs and functions to automatically adapt to accept input data of different data types
i.e. Numeric Functions
Useful when performing the same operation on different data types
In short, polymorphism is the ability of a node to accept/handle various data types.

57. Summary—Quiz Which function executes first: Add or Subtract? Add
Unknown
The answer is a.

58. Summary—Quiz Answer Which function executes first: Add or Subtract?
Unknown
The answer is a.

59. Summary—Quiz Which function executes first: Sine or Divide? Sine
Unknown
The answer is b.

60. Summary—Quiz Answer Which function executes first: Sine or Divide?
Unknown
The answer is b.

61. Summary—Quiz
Which of the following functions executes first: Random Number, Add or Divide?
Random Number
Divide
Add
Unknown
The answer is d.

62. Summary—Quiz Answer
Which of the following functions executes first: Random Number, Add or Divide?
Random Number
Divide
Add
Unknown
The answer is d.

63. Summary—Quiz
Which of the following functions execute last: Random Number, Subtract or Add?
Random Number
Subtract
Add
Unknown
The answer is b.

64. Summary—Quiz Answer
Which of the following functions execute last: Random Number, Subtract or Add?
Random Number
Subtract
Add
Unknown
The answer is b.

65. Summary—Quiz What are the three parts of a VI? Front Panel
Block Diagram
Project
Icon/Connector Pane
The answer is a, b, and d.

66. Summary—Quiz Answer What are the three parts of a VI? Front Panel
Block Diagram
Project
Icon/Connector Pane
The answer is a, b, and d.