LABVIEW:- INTRODUCTION

What is LabVIEW?
Why Use LabVIEW?
Application Areas?
How does LabVIEW work?
LabVIEW Toolkits and Modules?

What is LabVIEW ?

• LabVIEW – Laboratory Virtual Instrument Engineering Workbench

• Graphical programming language that allows for instrument control, data acquisition, and pre/post processing of acquired data

Graphical programming language & Data flow

• LabVIEW relies on graphical symbols rather than textual language to describe programming actions

• The principle of dataflow, in which functions execute only after receiving the necessary data, governs execution in a straightforward manner.

Why use LabVIEW ?
NI LabVIEW is a graphical programming language designed for engineers and scientists to develop test, control, and measurement applications. The intuitive nature of LabVIEW graphical programming makes it easy for educators and researchers to incorporate the software in a range of courses and applications. With LabVIEW, educators and researchers can use a graphical system design approach to design, prototype, and deploy embedded systems. It combines the power of graphical programming with hardware to dramatically simplify and accelerate the development of designs.

Graphical system design is a modern approach to designing, prototyping, and deploying embedded systems. It combines open graphical programming with hardware to dramatically simplify development.

Software Benefits
LabVIEW provides the flexibility of a powerful programming language without the complexity of traditional development environments.

· Easy to Learn and Use
· Complete Functionality
· Integrated I/O Capabilities

Instructor Benefits

· Exploration of Concepts
· Improved Learning Experience
· Seamless Integration with Hardware to Design Experiments
· Open Platform to Interface with Other Engineering Tools

Student Benefits

· Accelerated Learning
· Industry Standard

Application Areas?

LabVIEW is a flexible programming environment that can help you successfully build your unique application, whether you’re taking simple measurements or prototyping with FPGA technology.

How Can I Use LabVIEW?

Browse application areas about your specific application.

Acquiring Data and Processing Signals

Measure any sensor on any bus
Perform advanced analysis and signal processing
Display data on custom user interfaces
Log data and generate reports

Instrument Control

Automate data collection
Control multiple instruments
Analyze and display signals

Automating Test and Validation Systems

Automate the validation or manufacturing test of your product
Control multiple instruments
Analyze and display test results with custom user interfaces

Embedded Monitoring and Control Systems

Reuse ANSI C and HDL code
Integrate off-the-shelf hardware
Prototype with FPGA technology
Access specialized tools for medical, robotics, and more

Academic Teaching

Apply an interactive, hands-on approach to learning
Combine algorithm design with real-world data measurements
Increase application performance with multicore processing

How does LabVIEW work?

• LabVIEW programs are called: Virtual Instruments (VIs) because their appearence and operation imitate actual instruments.

• However, they are analogous to main programs, functions and subroutines from popular language like C, Fortran, Pascal, …

LabVIEW programs are called virtual instruments (VIs). As the name implies, you will be constructing an instrument that exists only in the computer, but otherwise similar to a tangible instrument, which will allow the user to send and receive meaningful data.

A VI has three main parts:

1. The front panel:

an interactive user interface of a VI, so named because it can simulates the front panel of a physical instrument.

This is where the user interacts directly with the VI. The front panel abstracts detail away from the user, and provides the user with as many inputs (or controls) and outputs (or indicators) required for the VI to function properly and meaningfully.

2. The block (or wiring) diagram:

It is the VI’s source code, constructed in LabVIEW’s graphical programming language, G. It is the actual executable program.

Subroutine in the block diagram of VI.

The block diagram, in several ways, represents a flowchart. It receives the input data supplied to the controls on the front panel, manipulates them in interesting ways through wires and blocks, and then displays the output data through the indicators on the front panel. As a corollary, every front panel control or indicator has a corresponding terminal on the block diagram.

3. Icon/connector

Another important part of any VI are the icons and the connectors. These allow your VI to communicate with other VIs elsewhere, and thus allows your VI to be used as a sub-VI in other VIs. This allows clean and modular block diagrams, where each sub-VI performs a certain task, and the inputs and results of each sub-VI are manipulated appropriately by the containing VI.

All of the available functions, blocks and VIs are located inside palettes.

There are two main palettes:

the Controls palette on the front panel and shown in Figure 1, and

the Functions palette on the block diagram, as shown in Figure 2. Both of these palettes are accessible by right-click.

Figure 1 Controls Palette

Figure 2 Function Palette

As denoted by their names, the Controls palette contains both the controls and the indicators that are available for use on the front panel, while the Functions palette contains the blocks and the VIs that are available for use on the block diagram. Since there are so many blocks possible and available, they have been categorized, and both of the main palettes have search functionalities that allow you to find any block that you think might be useful.

Front Panels

Simply put, the front panel is the window through which the user interacts with the program.

• When you run a VI, you must have the front panel open so that you can input data to the executing program.

• The front panel is where you see your program’s output.

Components of a front panel:

The front panel is primarily a combination of controls and indicators.

Control? or Indicator?

Controls = Inputs from the user = Source Terminals (Block With Arrow)

Indicators = Outputs to the user = Destinations (Block without Arrow)

Control or Indicator Terminal?

Control terminals have thick borders.

Indicator terminals have thin borders.

Manipulating Controls and Indicators

Right click on an indicator to

– Change to control

– Change format or precision

Right click on a control to

– Change to indicator

– Change mechanical action (whether to latch open or closed, and what to use as default…)

Deleting Block Diagram Terminals

• By default, you cannot delete a block diagram terminal that belongs to a control(or indicator).

• The terminal disappears only when you delete its corresponding control(or indicator) on the FRONT PANEL.

Block Diagrams

The block diagram window holds the graphical source code of a LabVIEW VI – it is the actual executable code

• You construct the block diagram by wiring together objects that perform specific functions.

• The various components of a block diagram are terminals, nodes and wires.

Terminals

When you place a control (or indicator) on the FRONT PANEL then LabVIEW automatically creates a corresponding control (or indicator) terminal on the BLOCK DIAGRAM

Nodes

Node is just a fancy word for a program execution element – Nodes are analogous to statements, operators, functions and

subroutinesin standard programming language:

• The add and subtract functions represent one type of node.

• A structure is an other type of node. Structures can execute code repeatedly or conditionally, similar to loops and case statements in traditional programming languages.

• LabVIEW has also special nodes, called formula nodes, which are useful for evaluating mathematical formulas or expressions.

Wires

A LabVIEW VI is held together by wires connecting nodes and terminals; they deliver data from one source terminal to one or more destination terminals.

Basic wires used in block diagrams and corresponding types

Each wire has different style or color, depending on the data type that flows through the wire:

Broken wires

If you connect more than one source or no source at all to a wire,

LabVIEW DISAGREES with what you’re doing, and the wirewill appear broken

Components of a block diagram
– Review ! –

• Nodes: program execution elements

• Terminals: Ports through which data passes between the block diagram and the front panel and between nodes of the block diagram

• Wires: Data paths between terminals

Dataflow Programming – Going with the flow

• Stated simply, a node executes only when data arrives at all its input terminals;

• the nodes supplies data to all of its output terminals when it finishes executing;

• and the data pass immediately from source to destination terminals.

LabVIEW uses a paradigm of programming known as dataflow programming. In the LabVIEW implementation of this paradigm, data flows fromleft to right, which passes through various blocks and modules that transform the data in interesting ways. This is analogous to a series of pipes connecting several machines together in, say, a factory; data can be imagined to be the liquid that flows through these pipes and machines. The user is provided with an interface through which to feed this data. The data is then processed and returned to the user through a similar interface.

Icons and Connectors

The icons and connectors specify the pathways for data to flow into and out of VIs.

• The icon is the graphical representation of the VI in the block diagram.

• the connector defines the inputs and outputs

Front Panel & Wiring Diagram.

• It is often helpful to view both simultaneously using the Windows-Tile Left and Right command from the pull down menu.

• A new (empty) VI is shown below with the key pull-down menu pallets visible.

Modifying a VI

• Only one of the two windows (front panel or wiring diagram) is active at any point in time. To activate one simply move the mouse over it and click a mouse button.

• To display any of the pallets (tools, controls, or functions) you can use the Windows pull down menu or simply left or right click your mouse.

• When you first pull up a pallet an image of a push pin is displayed in the upper left hand corner. Click on it to keep the pallet continuously displayed.

Tools palette . . .

Controls palette . . .

Functions palette . . .

Subpalettes . . .

Toolbar . . .

The Run Button

The Run button, which looks like an arrow, starts VI execution when you click on it	Run Button
It changes appearance when a VI is actually running.	Run Button (Active)
When a VI won’t compile, the run button is broken	Run Button (Broken)

LabVIEW Toolkits and Modules

LabVIEW (LV) is a graphic programming package ideal for creating automated test, measurement and control applications. The software acquires real world/real time signals and enables advanced, graphical analysis of the data. Available add-on modules and toolkits include the following:

Embedded Design - Design, prototype and develop embedded applications including LabVIEW Real Time, Execution Trace, FPGA, Microprocessor SDK, Statechart, Mobile, DSP, ADI Blackfin Processor and ARM Microcontroller embedded modules and toolkits
Control Design and Simulation - Algorithm development and analysis with LabVIEW Control Design and Simulation, Real-Time, Execution Trade, FPGA, Statechart, Simulation Interface and System Identification Modules and Toolkits
Image and Signal Processing – Create unique image and signal processing applications using LabVIEW Vision Development, Advanced Signal Processing, Digital Filter Design, Adaptive Filter, Sound/Vibration, Spectral, Modulation, Vision Builder/Automation and Math Interface Toolkits, Modules and Measurement Suites
Industrial Monitoring and Control – Utilize Labview in PACs (networked programmable automation controllers) for distributed monitoring and control systems and PLC/enterprise system integration with LabVIEW Real-Time, Execution Trace, FPGA, DataLogging/Supervisory Control, Touch Panel, Statechart, Motion Assistant and Softmotion Development Modules and Toolkits
Software Development – Create professional applications using LabVIEW Application Builder (Windows), Analyzer, Statechart, Remote Panels and Requirements Gateway Toolkits and Modules
Report Generation and Data Storage – Store data and generate reports with LabVIEW SignalExpress, Report Generation (Microsoft Office), Connectivity and Internet Toolkits