LabVIEW 8" Student Edition

Transcription

1 LabVIEW 8" Student Edition Robert H. Bishop The University of Texas at Austin PEARSON Prentice Hall Upper Saddle River, NJ 07458

2 CONTENTS Preface xvii LabVIEW Basics 1.1 System Configuration Requirements InstallingtheLabWEWSfudenfEd/f/on The LabVIEW Environment The Getting Started Screen Panel and Diagram Windows Front Panel Toolbar Block Diagram Toolbar Shortcut Menüs Pull-Down Menüs File Menü EditMenu View Menü Project Menü Operate Menü Tools Menü Window Menü Help Menü Palettes Tools Palette Controls Palette Functions Palette Opening, Loading, and Saving Vis 26

3 VÜi Contents 1.10 LabVIEW Help Options Context Help Window LabVIEW Help Building Blocks: Pulse Width Modulation Relaxed Reading: Remote Controlled Excavation with LabVIEW Summary 35 Exercises 37 Problems 41 Designs 42 2 Virtual Instruments What Are Virtual Instruments? Several Worked Examples The Front Panel Numeric Controls and Indicators Boolean Controls and Indicators Configuring Controls and Indicators The Block Diagram Vis and Express Vis Nodes Terminals Wiring Building Your First VI Data Flow Programming Building a VI Using Express Vis Building Blocks: Pulse Width Modulation Relaxed Reading: LabVIEW Automates Brain Wave Experiments Summary 86 Exercises 87 Problems 90 Designs 93 3 MathScript What is MathScript? Accessing the MathScript Interactive Window The Command History Window Copying Output Window Data Viewing Data in a Variety of Formats 100

4 ix 3.3 MathScript Help Syntax Key MathScript Functions Defining Functions and Creating Scripts User-Defined Functions Scripts Saving, Loading, and Exporting Data Files Saving and Loading Data Files Exporting to Microsoft Excel MathScript Nodes Accessing the MathScript Node Entering Scripts into the MathScript Node Input and Output Variables Saving Scripts from within the MathScript Node Applications of MathScript Instrument your Algorithms Graphical Signal Processing, Analysis, and Mathematics Integrating Measurement Hardware Building Blocks: Pulse Width Modulation Relaxed Reading Summary 141 Exercises 143 Problems 144 Designs Editing and Debugging Virtual Instruments Editing Techniques Creating Controls and Indicators on the Block Diagram Selecting Objects Moving Objects Deleting and Duplicating Objects Resizing Objects Labeling Objects Changing Font, Style, and Size of Text Selecting and Deleting Wires Wire Stretching and Broken Wires Aligning, Distributing, and Resizing Objects Coloring Objects 166

5 X Contents 4.2 Debugging Techniques Finding Errors Highlight Execution Single Stepping Through a VI and Its SubVIs Breakpoints and Probes Navigation Window AFewShortcuts Building Blocks: Pulse Width Modulation Relaxed Reading Summary 187 Exercises 188 Problems 191 Designs SubVIs What Is a SubVI? Review of the Basics Editing the Icon and Connector Icons Connectors Selecting and Modifying Terminal Patterns Assigning Terminals to Controls and Indicators The Help Window Using a VI as a SubVI Creating a SubVI from a Selection Saving Your SubVI The Hierarchy Window Building Blocks: Pulse Width Modulation Relaxed Reading: LabVIEW Real-Time at Biosphere Summary 223 Exercises 225 Problems 228 Designs Structures The For Loop Numeric Conversion The While Loop 239

6 xi 6.3 Shift Registers and Feedback Nodes Shift Registers Using Shift Registers to Remember Data Values from Previous Loop Iterations Initializing Shift Registers Feedback Nodes Case Structures Adding and Deleting Cases Wiring Inputs and Outputs Fiat Sequence Structures Evaluate and Control Timing in a Sequence Structure Avoid the Overuse of Sequence Structures The Formula Node Formula Node Input and Output Variables Formula Statements Some Common Problems in Wiring Structures Failing to Wire a Tunnel in All Cases of a Case Structure Overlapping Tunnels Wiring Underneath Rather Than Through a Structure Building Blocks: Pulse Width Modulation Relaxed Reading: Investigating Global Warming with LabVIEW Summary 278 Exercises 280 Problems 284 Designs Arrays and Clusters Arrays Creating Array Controls and Indicators Multidimensional Arrays Creating Arrays with Loops Creating Two-Dimensional Arrays Array Functions Array Size Initialize Array Build Array Array Subset Index Array 303

7 7.4 Polymorphism Clusters Creating Cluster Controls and Indicators Cluster Order Using Clusters to Pass Data to and from SubVIs Cluster Functions The Bündle Function The Unbundle Function Creating Cluster Constants on the Block Diagram Using Polymorphism with Clusters Building Blocks: Pulse Width Modulation Relaxed Reading: LabVIEW Monitors Medieval Bell Tower Summary 332 Exercises 334 Problems 337 Designs Charts and Graphs Waveform Charts Waveform Graphs XY Graphs Customizing Charts and Graphs Axes Scaling The Legend The Graph Palette and Scale Legend Special Chart-Customizing Features Special Graph-Customizing Features: Cursor Legend Using Graph Annotations Exporting Images of Graphs, Charts, and Tables Using Context Help Building Blocks: Pulse Width Modulation Relaxed Reading: Spacecraft Attitüde Determination on the Web Summary 378 Exercises 379 Problems 381 Designs 382

8 xiii 9 Data Acquisition Components of a DAQ System Types of Signals Digital Signals Analog DC Signals Analog AC Signals Analog Frequency-Domain Signals One Signal Five Measurement Perspectives Common Transducers and Signal Conditioning Signal Grounding and Measurements Signal Source Reference Configuration Measurement System Analog to Digital Conversion Considerations DAQ VI Organization Choosing Your Data Acquisition Device M-Series Data Acquisition Devices Low Cost Data Acquisition for Students Simulated Data Acquisition Macintosh, Linux, Palm OS, Windows Mobile for Pocket PC, and select Windows CE OS devices DAQ Hardware Configuration Windows Channels and Tasks Using the DAQ Assistant DAQmx Task Name Constant Analog Input TaskTiming Task Triggering Analog Output TaskTiming Task Triggering Digital Input and Output Building Blocks: Pulse Width Modulation Generating Pulse Width Modulated Signals with Hardware Counters Applications of Pulse Width Modulation Relaxed Reading: Fuel Cell Catalyst Research 451

9 9.15 Summary 453 Exercises 457 Problems 457 Designs Strings and File I/O Strings Converting Numenc Values to Strings with the Build Text Express VI File I/O Writing Data to a File Reading Data from a File Manipulating Spreadsheet Files File I/O Express Vis Building Blocks: Pulse Width Modulation Relaxed Reading: Using LabVIEW in Drive-by-Wire Testing Summary 488 Exercises 489 Problems 491 Designs Analysis Linear Algebra Review of Matrices System of Algebraic Equations Linear System Vis Statistics and Curve Fitting Curve Fits Based on Least Squares Methods Fitting a Curve to Data with Normal Distributions The Curve Fitting Express VI Differential Equations Finding Zeroes of Functions Integration and Differentiation Signal Generation Normalized Frequency Wave and Pattern Vis The Simulate Signal Express VI 533

10 XV 11.7 Signal Processing The Fourier Transform Smoothing Windows The Spectral Measurements Express VI Filtering The Filter Express VI The LabVIEW Digital Filter Design Toolkit Building Blocks: Pulse Width Modulation Relaxed Reading: Motorcycle Brake Testing Summary 564 Exercises 566 Problems 567 Designs 568 A Instrument Control 569 A.1 Components of an Instrument Control System 570 A.1.1 WhatlsGPIB? 570 A.1.2 GPIB Messages 571 A.1.3 GPIB Devices and Configurations 571 A.1.4 Serial Port Communication 575 A.2 Detecting and Configuring Instruments 576 A.2.1 Windows 577 A.2.2 Macintosh OS X and Linux 577 A.3 Using the Instrument I/O Assistant 580 A.4 Instrument Drivers 587 A.4.1 Developing Your Own Instrument Driver 593 A.5 Future of Instrument Drivers and Instrument Control 594 A.6 Summary 595 B Other LabVIEW Applications 597 B.1 Acquiring Data with the Sound Card 598 B.2 Managing Programs with the LabVIEW Project 598 B.3 Sharing Data with Shared Variables 600 B.4 LabVIEW Toolkits 602 B.5 Prototyping a Model-Based Control Solution 603 B.5.1 Developing a Plant Model 603 B.5.2 Control Design 604 B.5.3 Simulation 605 B.5.4 Deployment 606

11 XVI Contents B.6 Using Multisim for Integrated Circuit Simulation and Verification 607 B.7 Summary 609 Index 611