for Scientists and Engineers - Reed College

1 Hands-On introduction toLabVIEW for Scientists and EngineersSecond Edition John EssickReed College New York OxfordOXFORD UNIVERSITY iii4/10/2012 10:07:09 PMviiContentsPreface xiii1. THE WHILE LOOP AND WAVEFORM CHART 1 labview Programming Environment 1 Sine-Wave Plot using a While Loop and Waveform Chart 2 Block Diagram Editing 3 labview Help Window 20 Front Panel Editing 22 Pop-Up Menu 27 Finishing the Program 30 Program Execution 31 Program Improvements 33 Date-Type Representations 43 Automatic Creation Feature 46 Program Storage 48 Do It Yourself 50 Problems 512. THE FOR LOOP AND WAVEFORM GRAPH 56 For Loop Basics 56 Sine-Wave Plot using a For Loop and Waveform Graph 57 Waveform Graph 58 Owned and Free Labels 59 Creation of Sine Wave using a For Loop 60 Cloning Block-Diagram Icons 63 Auto-Indexing Feature 65 Running the VI 68 x-Axis Calibration of the Waveform Graph 69 Sine-Wave Plot using a While Loop and Waveform Graph 75 Array Indicators and the Probe Watch Window 79 Do It Yourself 90 Problems vii4/10/2012 10:07:10 PMviiiContents3.

2 THE MATHSCRIPT NODE AND X Y GRAPH 99 MathScript Node Basics 99 Quick MathScript Node Example: Sine-Wave Plot 102 Debugging with Error List 109 Waveform Simulator using a MathScript Node and XY Graph 111 Creating an xy Cluster 115 Running the VI 116 MathScript Interactive Window 117 Adding Shape Options to Waveform Simulator 121 The Enumerated Type Control 122 Finishing the Block Diagram 124 Running the VI 128 Control and Indicator Clusters 129 Creating an Icon using the Icon Editor 136 Icon Design 137 Connector Assignment 142 Do It Yourself 146 Problems 1484. DATA ACQUISITION USING DAQ ASSISTANT 152 Data Acquisition VIs 152 Data Acquisition Hardware 153 Analog Input Modes 155 Range and Resolution 157 Sampling Frequency and the Aliasing Eff ect 158 Measurement & Automation Explorer (MAX) 160 Simple Analog Input Operation on a DC Voltage 164 Digital Oscilloscope 175 Analog Output 184 DC Voltage Source 185 Software-Timed Sine-Wave Generator 192 Hardware-Timed Waveform Generator 194 Placing a Custom-Made VI on a Block Diagram 197 Completing and Executing Waveform Generator (Express) 199 Modifi ed Waveform Generator 201 Do It Yourself 203 Problems viii4/10/2012 10:07:10 PMixCONTENTS5.

3 DATA FILES AND CHARACTER STRINGS 211 ASCII Text and Binary Data Files 211 Storing Data in a Spreadsheet-Formatted File 213 Storing a One-Dimensional Data Array 214 Transpose Option 217 Storing a Two-Dimensional Data Array 220 Controlling the Format of Stored Data 224 The Path Constant and Platform Portability 226 Fundamental File I/O VIs 227 Adding Text Labels to a Spreadsheet File 233 Blackslash Codes 237 Do It Yourself 239 Problems 2426. SHIFT REGISTERS 252 Shift Register Basics 252 Quick Shift Register Example: Integer Sum 255 Numerical Integration and Diff erentiation using Shift Registers 258 Power Function Simulator VI 258 Numerical Integration via the Trapezoidal Rule 264 Trapezoidal Rule VI using Single Shift Register 267 Convergence Property of the Trapezoidal Rule 275 Numerical Diff erentiation using a Multiple Shift Registers 278 Modularity and Automatic SubVI Creation 284 Do It Yourself 289 Problems 2897.

4 THE CASE STRUCTURE 296 Case Structure Basics 296 Quick Case Structure Example: Runtime Options using Property Nodes 299 Numerical Integration using Case Structures 310 Numerical Integration via Simpson s Rule 310 Parity Determiner using a Boolean Case Structure 313 Summation of Partial Sums using a Numeric Case Structure 318 Trapezoidal Rule Contribution using a Boolean Case Structure 321 Top-Level Simpson s Rule VI 323 Comparison of the Trapezoidal Rule and Simpson s Rule 326 Do It Yourself 329 Problems ix4/10/2012 10:07:10 PMxContents 8. DATA DEPENDENCY AND THE SEQUENCE STRUCTURE 338 Data Dependency and Sequence Structure Basics 338 Event Timer using a Sequence Structure 342 Event Timer using Data Dependency 349 Highlight Execution 352 Do It Yourself 354 Problems 355 9.

5 ANALYSIS VIS CURVE FITTING 364 Thermistor Resistance-Temperature Data File 364 Temperature Measurement using Thermistors 367 The Linear Least-Squares Method 370 Inputting Data to a VI using a Front-Panel Control 371 Inputting Data to a VI by Reading from a Disk File 376 Slicing Up a Multi-Dimensional Array 379 Curve Fitting using the Linear Least-Squares Method 385 Residual Plot 391 Do It Yourself 394 Problems 39710. ANALYSIS VIS FAST FOURIER TRANSFORM 405 The Fourier Transform 405 Discrete Sampling and the Nyquist Frequency 406 The Discrete Fourier Transform 407 The Fast Fourier Transform 408 Frequency Calculator VI 409 FFT of Sinusoids 412 Applying the FFT to Various Sinusoidal Inputs 414 Magnitude of the Complex-Amplitude 417 Observing Leakage 421 Analytic Description of Leakage 427 Description of Leakage Using the Convolution Theorem 430 Windowing 434 Estimating Frequency and Amplitude 440 Aliasing 443 Do It Yourself 444 Problems x4/10/2012 10:07:10 PMxiCONTENTS11.

6 DATA ACQUISITION AND GENERATION USING DAQMX VIS 451 DAQmx VIs 451 Simple Analog Input Operation on a DC Voltage 453 Digital Oscilloscope 459 Express VI Automatic Code Generation 466 Limitation of Express VIs 467 Improving Digital Oscilloscope using State Machine Architecture 469 Analog Output Operations 480 Waveform Generator 481 Do It Yourself 485 Problems 48512. PID TEMPERATURE CONTROL PROJECT 491 Voltage-Controlled Bi-Directional Current Driver forThermoelectric Device 491 PID Temperature Control Algorithm 492 PID Temperature Control System 49513. CONTROL OF STAND-ALONE INSTRUMENTS 498 Instrument Control using VISA VIs 498 The VISA Session 499 The IEEE Standard 503 Common Commands 503 Status Reporting 504 Device-Specifi c Commands 508 Specifi c Hardware used in this Chapter 509 Measurement & Automation Explorer (MAX)

7 511 Simple VISA-Based Query Operation 518 Message Termination 522 Getting and Setting Communication Properties using a Property Node 523 Performing a Measurement over the Interface Bus 527 Synchronization Methods 532 Measurement VI Based on the Serial Poll Method 538 Measurement VI Based on the Service Request Method 545 Creating an Instrument Driver 551 Using the Instrument Driver to Write an Application Program 565 Do It Yourself 571 Problems 572 APPENDIX I: CONSTRUCTION OF TEMPERATURE CONTROL SYSTEM 575 APPENDIX II: PROGRAM CROSS REFERENCE TABLE xi4/10/2012 10:07:10 PM