Labview

NI LabVIEW Environment: Detailed Explanation
Virtual Instruments (VIs)
LabVIEW programs are called virtual instruments, or VIs, because their appearance and operation imitate physical instruments, such as oscilloscopes and multimeters. LabVIEW contains a comprehensive set of tools for acquiring, analyzing, displaying, and storing data as well as tools to help you troubleshoot the code youwrite. When you create a new VI, you see two windows: the front panel window and the block diagram.

Front Panel
When you open a new or existing VI, the front panel window of the VI appears. The front panel window is the user interface for the VI. Figure 1 shows an example of a front panel window.

Figure 1. Front Panel Window, Toolbar, and Controls Palette

Controls Palette
The Controlspalette contains the controls and indicators you use to create the front panel. You access the Controls palette from the front panel window by selecting View >> Controls Palette or by right-clicking on any empty space in the front panel window. The Controls palette is broken into various categories; you can expose some or all of these categories to suit your needs. Figure 2 shows a Controls palette withall of the categories exposed and the Modern category expanded.

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Figure 2. Controls Palette

To view or hide categories (subpalettes), select the View button on the palette and select or deselect in the Always Visible Categories option.

Controls and Indicators
You create the front panel with controls and indicators, which are the interactive input andoutput terminals of the VI, respectively. Controls are knobs, push buttons, dials, and other input devices. Indicators are graphs, LEDs, and other displays. Controls simulate instrument input devices and supply data to the block diagram of the VI. Indicators simulate instrument output devices and display data that the block diagram acquires or generates. Figure 1 has two controls: Number ofMeasurements and Delay (sec). It has one indicator: an XY graph named Temperature Graph. The user can change the input value for the Number of Measurements and Delay (sec) controls. The user can see the value generated by the VI on the Temperature Graph indicator. The VI generates the values for the indicators based on the code created on the block diagram. Every control or indicator has a data typeassociated with it. For example, the Delay (sec) horizontal slide is a numeric data type. The most commonly used data types are numeric, Boolean value, and string.

Numeric Controls and Indicators
The numeric data type can represent numbers of various types, such as integer or real. The two common numeric objects are the numeric control and the numeric indicator, as shown in Figure 3. Objects such asmeters and dials also represent numeric data. To enter or change values in a numeric control, click the increment and decrement or double-click the number, enter a new number, and press the key.

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Figure 3. Numeric Control Increment/Decrement, Control, Indicator

Boolean Controls and Indicators
The Boolean data type represents data that has only two possiblestates, such as TRUE and FALSE or ON and OFF Use Boolean controls and indicators to enter and display Boolean values. Boolean objects simulate . switches, push buttons, and LEDs. The vertical toggle switch and the round LED Boolean objects are shown in Figure 4.

Figure 4. Boolean Controls and Indicators

String Controls and Indicators
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. The most common string objects are tables and text entry boxes, as shown in Figure 5.

Figure 5. String Controls and Indicators

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Block Diagram
Block diagram objects include terminals, subVIs, functions, constants, structures,...