Making Decisions with the Select Function 1.1 2004/06/23 10:38:24 GMT-5 2004/07/16 15:18:55.542 GMT-5 National Instruments certification@ni.com Elizabeth Gregory lizzardg@rice.edu Malan Shiralkar mshiralkar05@hotmail.com Harika Basana ilsai@rice.edu National Instruments certification@ni.com National Instruments LabVIEW decision select In this lesson, you will learn about making decisions with the Select function. Every VI described in this course so far has executed in an order dependent on the flow of data. There are cases when a decision must be made in a program. For example, if a happens, do b; else if c happens, do d. In text-based programs, this can be accomplished with if-else statements, case statements, switch statements, and so on. LabVIEW includes many different ways of making decisions. The simplest of these methods is the Select function.

Select Function The Select function, located on the Functions>>Express Comparison palette, selects between two values dependent on a Boolean input. If the Boolean input s is True, this function returns the value wired to the t input. If the Boolean input is False, this function returns the value wired to the f input. You used the Select function in the Thermometer VI exercise to determine whether to output a Fahrenheit value or a Celsius value, as shown in the block diagram in .

If the decision to be made is more complex than a Select function can execute, a Case structure may be required.