Using LabVIEW Case Structures

Summary

In this tutorial, Venit explains how to use case structures in LabVIEW to selectively execute code, similar to if-then-else or switch statements in other programming languages. Venit demonstrates how a case structure can be used to toggle between degrees Fahrenheit and Celsius based on user input through a Boolean switch. The tutorial also covers using numeric controls for more complex cases, allowing for additional customized functionality like displaying a constant value, regardless of the input. This approach showcases the versatility of case structures in LabVIEW for dynamic programming.

Takeaways

• 😀 A case structure in LabVIEW allows you to conditionally execute code, similar to 'if-then-else' or 'switch' statements in other programming languages.
• 😀 You can create a graphical case structure by right-clicking on the block diagram and selecting 'Case Structure' from the structures palette.
• 😀 The case structure in LabVIEW can execute different sections of code based on a Boolean input (true/false).
• 😀 A common use for a case structure is allowing the user to switch between different units of measurement, such as Fahrenheit and Celsius.
• 😀 The case structure has a 'case selector input' that determines which code block will be executed based on the input value.
• 😀 You can control the case selector with a Boolean switch, which allows the user to toggle between different cases in the program.
• 😀 The case structure in LabVIEW is versatile and can handle more than just true/false conditions, allowing for numeric values as selectors.
• 😀 By adding multiple cases, you can execute different code based on different numeric values, such as displaying specific temperature values (e.g., 78°).
• 😀 A numeric control can be used to select different cases in the case structure, giving you more flexibility in controlling program flow.
• 😀 LabVIEW's case structure simplifies the process of creating conditional logic in graphical programs, making it intuitive for users familiar with other programming languages.

Q & A

What is the main purpose of a case structure in LabVIEW?

A case structure in LabVIEW is used to selectively execute different sections of code based on conditions, similar to 'if-then-else' or 'switch' statements in other programming environments.

How does the case structure work in LabVIEW?

In LabVIEW, the case structure uses a 'case selector' input to determine which piece of graphical code to execute. The case structure can be configured with multiple conditions (e.g., Boolean or numeric) to control which code path to follow.

What type of control is used to select between Fahrenheit and Celsius in the example?

A Boolean toggle switch is used to select between Fahrenheit and Celsius in the example. When the toggle switch is set to 'true', the temperature is converted to Celsius, and when 'false', the original Fahrenheit value is displayed.

What is the default case in the case structure when no condition is specified?

By default, the case structure starts with a 'true' case and executes the code within that case, which is initially set to display Fahrenheit values in the example.

How can more cases be added to the case structure?

To add more cases to the case structure, you can right-click on the border of the case structure and select 'Add Case After'. This allows you to include additional conditions for the code to execute.

What happens when a numeric control is used to select the case in the case structure?

When a numeric control is used as the case selector, you can define multiple cases that execute based on specific numeric values, such as showing a constant temperature when a certain number is passed to the case selector.

What does the third case represent in the example provided?

The third case in the example represents a scenario where the numeric selector is set to 2, and in this case, a constant value of 78 degrees is always displayed on the thermometer, regardless of the slider value.

What does the slider do in the program example?

The slider in the program adjusts the temperature value, and the corresponding temperature is displayed on the thermometer. The values can be shown either in Fahrenheit or Celsius, depending on the case selected.

How can a user switch between displaying Fahrenheit and Celsius?

The user can switch between displaying Fahrenheit and Celsius by toggling a Boolean switch. When the switch is set to 'true', the temperature is displayed in Celsius; when set to 'false', it is displayed in Fahrenheit.

What happens when the numeric control is set to 1 in the case structure?

When the numeric control is set to 1, the program will display the temperature in Celsius. The slider allows the user to adjust the temperature, and the corresponding Celsius value is shown on the thermometer.