LabVIEW Basics II Slides

1LabVIEW Basics II

LabVIEW Basics II: Development

11500 North Mopac ExpresswayAustin, Texas 78759

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What You Need To Get Started

LabVIEW Basics II Course Manual LabVIEW Basics II Course CD Multifunction DAQ device

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Computer running LabVIEW 8.6 or later

and Windows 2000 or later

Multifunction DAQ device DAQ Signal Accessory, wires, and cable

File Locations

The course installer places the course files in the following location:

Exercises LabVIEW

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Root Directorye c ses

SolutionsLabVIEW Basics II

Instructional Methods

Lecture gives a foundation in the topic

Instructor reinforces foundation through

TopicLecture

Quizzes

Demonstrations

Concept Exercise

Development Exercise

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demonstrations and quizzes Use concept exercises to further explore a topic Watch a simulation, experiment with example VIs

Use development exercises to gain hands-on experience Demonstration of a finished development exercise further

reinforces the learning process

Getting The Most Out Of This Course

Experiment with hands-on exercises to understand the methods used

Implementations explore a possible solutionyou may find a better one

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Do not come to class prepared to develop an outside application; concentrate on the exercises given to build a good foundation

Courses

New User

LabVIEW Basics I

LabVIEW Basics II

Experienced User

LabVIEW Intermediate I

LabVIEW Intermediate II

Advanced User

LabVIEW Advanced I

Skills learned: LabVIEW environment

navigation Basics application creation

using LabVIEW Basics of data acquisition and

Skills learned: Modular application

development Structured design and

development practices Inter-application

Skills learned: Large application design Advanced development

techniques Implementing multideveloper

projects

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Certifications

Certified LV Associate Developer Exam

Skills tested: LabVIEW environment

knowledge

Certified LabVIEW Developer Exam

Skills tested: LabVIEW application

development expertise

Certified LabVIEW Architect Exam


development mastery

Basics of data acquisition and instrument control

Inter-application communication and connectivity techniques

projects

2Course Learning Map

Lesson 2

Communicating Among Multiple Loops

Lesson 1

Common Design Techniques

Lesson 6

Advanced File I/O

Lesson 5

Controlling the User Interface

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Lesson 4

Improving an Existing VI

Lesson 3

Event ProgrammingLesson 7

Creating & Distributing an Executable

Course Goals

This course prepares you to: Design, implement and distribute stand-alone applications Apply single and multiple loop design patterns Use event programming effectively

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Use event programming effectively Programmatically control user interface objects Apply data management techniques Optimize reuse of existing code for your projects

TOPICS

Lesson 1Common Design Techniques

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A. Single Loop ArchitecturesB. ParallelismC. Multiple Loop ArchitecturesD. EventsE. Timing a Design Pattern

A. Single Loop Architectures

Simple Single VI that takes a measurement, performs calculations,

and either displays the results or records them to disk Usually does not require a specific start or stop action from

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ythe user

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General VI Three phases: Start-up, Main Application, and Shut-down

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General VI

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3A. Single Loop Architectures

State Machine Usually has a start-up and shut-down state, but also

contains other states

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State Machine

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B. Parallelism

Execute multiple tasks at the same time

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B. Parallelism

Passing data among parallel loops is a challengeHow do the loops stop in this example?

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B. Parallelism

How do the loops stop in this example?

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B. Parallelism

Read the Stop button from a file Each loop independently accesses the file However, reading and writing to files can consume much

processor time

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p

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4C. Multiple Loop Architectures

Parallel Loop

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C. Multiple Loop ArchitecturesProducer/Consumer

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D. Events

What are events? Influence block diagram execution with events Events are an asynchronous notification indicating that

something occurred

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g Events originate from the user interface, external I/O, or

other parts of the program

User Actions on the Front Panel

Sy

D. Events

Why use events?

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Block Diagram Execution

ynchronize

D. Events

Event Programming

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Execution

E. Timing a Design Pattern - Execution

Execution Timing Provides the design pattern with a function that specifically

allows the processor time to complete other tasks In some cases, a function is not necessary

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y

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5E. Timing a Design Pattern Execution

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E. Timing a Design Pattern Software Control

Software Control Timing Consider implementing a state machine design pattern for

a data acquisition system If you must acquire data for 5 minutes, you could remain in

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y q ythe acquisition state until the 5 minutes elapses

However, during that time you cannot process any user interface actions such as stopping the VI

To process user interface actions, you must implement timing so that the VI continually executes for the specified time

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E. Timing a Design PatternExecution Timing

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Software Control Timing

SummaryQuiz

Are the following statements True or False? Software control timing allows the processor time to

complete other tasks. Execution timing allows the processor time to complete

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gother tasks.

You can use a wire to pass data among parallel loops.

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SummaryQuiz Answers

Are the following statements True or False? False. Software control timing is a method for monitoring a

real-time clock. True. Execution timing allows the processor time to

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g pcomplete other tasks.

False. If you pass data between two loops with a wire, the loops no longer run in parallel.

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1TOPICS

Lesson 2Communicating Among Multiple Loops

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A. VariablesB. Functional Global VariablesC. Race ConditionsD. Synchronizing Data

A. Variables

Cannot pass data between parallel loops with a wire Variables allow you to circumvent normal dataflow by

passing data from one place to another without connecting the two places with a wire

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A. Variables

Variables are block diagram elements that allow you to access or store data in another location

Variables can be of the following types: Local: store data in front panel controls and indicators

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Global: store data in special repositories that can be accessed from multiple VIs

Functional Global: store data in While Loop shift registers Shared: transfers data between various distributed targets

connected together over a network

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A. Variables Using in a Single VI

Use local variables to pass data within a single VI

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Demo: Creating Local Variables

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GOAL

Create and use local variables.

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A. Variables Using Between VIs

Use a global variable or a single process shared variable to share data between multiple VIs Use a global variable to share data among VIs on the same

computer, especially if you do not use a project file

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Use a single process shared variable if you may need to share the variable information among VIs on multiple computers in the future

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2Demo: Creating Global Variables

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GOAL

Create and use global variables.

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Demo: Creating Shared Variables

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GOAL

Create and use single process shared variables.

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A. Variables Using Carefully

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A. Variables Using Carefully

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A. Variables Initializing

Verify that variables contain known data values before the VI runs

If you do not initialize the variable before the

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VI reads it for the first time, it contains the default value of the associated front panel object

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A. Variables Initializing

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3B. Functional Global Variables

The general form of a functional global variable includes an uninitialized shift register (1) with a single iteration For or While Loop

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B. Functional Global Variables

A functional global variable usually has an action input parameter that specifies which task the VI performs

The VI uses an uninitialized shift register in a While Loop to hold the result of the operation

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B. Functional Global Variables Timing

Very useful for performing customized elapsed time measurements

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Exercise 2-1: Variables VI

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GOAL

Use variables to write to and read from a control.

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Exercise 2-2: Global Data Project

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GOAL

OPTIONALCreate a project containing multiple VIs that share data using a single process shared variable.

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C. Race Conditions

A race condition is a situation where the timing of events or the scheduling of tasks may unintentionally affect an output or data value

Race conditions are a common problem for programs that

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execute multiple tasks in parallel and share data between the tasks

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4Demo: Race Conditions

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GOAL

Watch the instructor demonstrate race conditions.

C:/Exercises/LabVIEW Basics II/Demonstrations

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C. Race Conditions

Race conditions are very difficult to identify and debug Often, code with a race condition can return the same

result thousands of times in testing, but still be capable of returning a different result

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Avoid race conditions by: Controlling shared resources Properly sequencing instructions Identifying and protecting critical sections within your code Reducing use of variables

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C. Race Conditions Shared Resources

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C. Race Conditions Critical Code

A critical section of code is code that may behave inconsistently if some shared resource is altered while it is running

If one loop interrupts another loop while it is executing

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critical code, then a race condition can occur Eliminate race conditions by identifying and protecting

critical code with: Functional Global Variables Semaphores

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Functional Global Variable used to protect critical code:

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5C. Race Conditions Critical Code

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C. Race Conditions Sequencing

What is the final value?Four possible outcomes: Value = (Value * 5) +2 Value = (Value + 2) * 5

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Value (Value 2) 5 Value = Value * 5 Value = Value +2

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Exercise 2-3: Bank VI

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GOAL

Eliminate a race condition by protecting a critical section of code.

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D. Synchronizing the Transfer of Data

Variables are one method for passing data between parallel processes

Using variables breaks the LabVIEW dataflow paradigm, allows for race conditions, and incurs more overhead

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than passing the data by wire

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Demo: Notifiers

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GOAL

Open the Master/Slave Design Pattern template in LabVIEW and explore the operation of Notifiers.

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6D. Synchronizing the Transfer of Data

The following benefits result from using Notifiers to transfer data between parallel loops: Both loops are synchronized to the master loopthe slave

loop only executes when the master loop sends a

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notification You can use Notifiers to create globally available data,

making it possible to send data with a notification Using Notifiers creates efficient codethere is no need to

poll to determine when data is available from the master loop

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Notifier disadvantages: A notifier does not buffer data If the master loop sends another piece of data before the

first piece of data has been read by the slave loops, that

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p y pdata is overwritten and lost

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Queues are similar to notifiers, except that a queue can store multiple pieces of data

By default, queues work in a FIFO (first in, first out) manner Use a queue when you want to process all data placed in

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ythe queue

Use a notifier if you only want to process the current data

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Demo: Queues

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GOAL

Open the Producer/Consumer Design Pattern (data) template in LabVIEW and explore the operation of Queues.

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Demo: Weather Station

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GOAL

Demonstrate the use of queues for data transfer and synchronization of parallel loops.

C:/Exercises/LabVIEW Basics II/Demonstrations/Case Study - Queue

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7Exercise 2-4: Queues vs Local Variables VI

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GOAL

Examine a built-in producer/consumer design pattern VI that uses queues to avoid race conditions and synchronize the data transfer between two independent parallel loops.

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SummaryQuiz

1. You should use variables in your VI where ever possible.a) True b) False

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SummaryQuiz Answer

1. You should use variables in your VI where ever possible.a) True b) False

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SummaryQuiz

2. Which cannot transfer data?a) Semaphores b) Functional global variablesc) Notifiers d) Q

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d) Queues

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SummaryQuiz Answer

2. Which cannot transfer data?a) Semaphores b) Functional global variablesc) Notifiers d) Q

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d) Queues

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SummaryQuiz

3. Which can you use only within a project?a) Local variableb) Global variable c) Functional global variable d) Si l h d i bl

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d) Single-process shared variable

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8SummaryQuiz Answer

3. Which can you use only within a project?a) Local variableb) Global variable c) Functional global variable d) Si l h d i bl

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SummaryQuiz

4. Which cannot be used to pass data between multiple VIs?a) Local variableb) Global variable c) Functional global variable d) Si l h d i bl

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SummaryQuiz Answer

4. Which cannot be used to pass data between multiple VIs?a) Local variableb) Global variable c) Functional global variable d) Si l h d i bl

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1TOPICS

Lesson 3: Event Programming

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A. Event Driven ProgrammingB. Event Based Design Patterns

The Event Structure

Examples of User Interface (Static) Events Pressing a button on the

mousePressing a ke on the

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Pressing a key on the keyboard

Value (Signaling) Property can generate a programmatic event

Parts of an Event Structure

Event Selector Label identifies event case viewed Timeout value in ms to wait for events; default value is 1

(indefinite) Dynamic Event Terminals used for dynamic event registration Default Tunnel Values

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Default Tunnel Values new type of tunnel which allows unwired cases to provide default values

Parts of an Event Structure (continued)

Event Data Node identifies the data LabVIEW provides when the event occurs; similar to the Unbundle By Name functionEvent Filter Node identifies the subset of data available in the Event Data Node that the event case can modify

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Event Structure Basic Usage

Normally used in a While Loop Sleeps and handles exactly one event per iteration Event Data available in terminals on structures left border Can right-click on Event

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Can right click on Event Data and show only the terminals you need

Event Structure Configuration

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Use a dialog box to configure events byright-clicking the Event structure border and selecting Edit Events Handled by This Case from the shortcut menu

2Edit Events Dialog

1. Configured Events

2. Event Sources

3. Events

1

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Notify Events (green arrow)Notifies LabVIEW that a user action has already occurred; available only in the Event Data Node

Notify and Filter Events

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Filter Events (red arrow)Validates or changes the event data before the user interface can process it; available in the Event Filter Node and Event Data Node

Event Registration and Panel Locking

Events are registered when a VI with an Event structure on its block diagram becomes reserved

When a registered event occurs, it is queued until the Event structure(s) configured for it executes

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It is not possible to miss events or process them out of order

By default, the front panel is locked until the event is handled You can turn off locking, but only for Notify Events

Events are unregistered when the VI becomes idle

Exercise 3-1: Experiment with Event Structures

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GOAL

ConceptExperiment with the operation of the Event Structure in a VI.

Event-Based Design Pattern

Use the user interface event handler design pattern for detecting when a user changes the value of a control, moves or clicks the mouse, or presses a key

The user interface event handler allows you to minimize

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processor use without sacrificing interactivity

User Interface Event Handler

1. Event StructureConfigure the Event structure to have one frame for each category of event you want to detect

2. While Loop3. Timeout Terminalallows you to control when the Timeout event

executes

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executes4. Event Data Node 3

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1

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3Producer/Consumer (Events)

Benefits Efficiently

responds asynchronously to the user

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interface Queues can

transfer any data type

Exercise 3-2: Experiment with Event-Based Design Patterns

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GOAL

ConceptObserve the functionality and design of event-based LabVIEW design patterns

SummaryQuiz

1. True or False? Event Structures are normally used in While Loops.

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SummaryQuiz Answer

1. Event Structures are normally used in While Loops. True.

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SummaryQuiz

2. Which of the following are examples of user interface events?a) Mouse clickb) Keystroke

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) yc) Event Filter Noded) Value change of a control

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SummaryQuiz Answer

2. Which of the following are examples of user interface events?a) Mouse clickb) Keystroke

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) yc) Event Filter Noded) Value change of a control

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4SummaryQuiz

3. True or False? Using user interface events allows you to synchronize user actions on the front panel with block diagram execution.

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SummaryQuiz Answer

3. Using user interface events allows you to synchronize user actions on the front panel with block diagram execution. True.

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1TOPICS

Lesson 4Controlling the User Interface

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A. VI Server ArchitectureB. Property NodesC. Control ReferencesD. Invoke Nodes

A. VI Server Architecture

VI Server performs many functions; however, this lesson concentrates on using VI Server to control front panel objects and edit the properties of a VI

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Terminology: An object is a member of a class A class defines what an object is able to do, what

operations it can perform (methods), and what properties it

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( )has

Methods perform an operation on an object Properties are the attributes of an object

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A. VI Server Architecture Example

Control ClassProperty: VisibleMethod: Reinitialize to Default

Array Sub-ClassBoolean S b Class

Control

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Array Sub ClassProperty: Number of Rows

Boolean Sub-ClassProperty: Boolean Text

Stop ObjectVisible: YesReinitialize to Default: NoBoolean Text: Stop

Boolean

Stop

Array


Control Classes LabVIEW front panel objects inherit properties and methods

from a specific control class VI Class

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Your VI belongs to the VI Class and has its own properties and methods associated with it

Example Methods: abort your VI, adjust the position of the front panel, get an image of the block diagram

Example Properties: change the title of your front panel window, retrieve the size of the block diagram, hide the abort button

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B. Property Nodes

Property Nodes access the properties of an object In some applications, you might want to modify the

appearance of front panel objects programmatically in response to certain inputs

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If a user enters an invalid password, you might want a red LED to start blinking

If a data point is above a certain value, you might want to show a red trace instead of a green one

Property Nodes allow you to make these modifications programmatically

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2Demo: Property Nodes

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GOAL

Create a Property Node for a front panel object, choose a property to set and choose a property to read.

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B. Property Nodes Execution Order

Property Nodes execute in order from top to bottom If an error occurs on a terminal, the node stops at that

terminal, returns an error, and does not execute any further terminals

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Exercise 4-1: Temperature Limit VI

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GOAL

Use Property Nodes to change the properties of front panel objects programmatically.

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C. Control References Implicit vs. Explicit

Main VIMain VI

Implicitly Linked Property Node Explicitly Linked Property Node

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VI VI SubVI

C. Control References

A control reference is a reference to a front panel object Wire control references to

generic Property Nodes Pass control references

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to subVIs

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C. Control References Create SubVI

To create explicitly-linked Property Nodes in a subVI:1. Create your VI2. Select the portion of the block

diagram that will be in the subVI

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g3. Select EditCreate SubVI;

LabVIEW automatically creates the control references needed for the subVI

4. Customize and save the subVI

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3C. Control References Create SubVI

S bVI F t P l S bVI Bl k Di

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SubVI Front Panel SubVI Block Diagram

C. Control References Create yourself

S bVI F t P l S bVI Bl k Di

Control Reference

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SubVI Front Panel SubVI Block Diagram

Ctl Refnum

C. Control References Selecting Class

After you place a Control Refnum on the front panel of a subVI, specify the VI Server class of the control Right-click and select VI Server Class from the shortcut

menu

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Specifies the type of control references that the subVI accepts

In the previous example, Control was the VI Server class Allows the VI to accept a reference to any type of front panel

control

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C. Control References Selecting Class

Specifying a more specific class for the refnum makes the subVI more restrictive

For example, you can select Digital as the class, and the subVI can only accept references

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to numeric controls of the class Digital Selecting a more generic class for a control refnum allow it

to accept a wider range of objects but limits the properties available

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Exercise 4-2: Set Plot Names

Set Plots.vi

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GOAL

Use control references to create a subVI that modifies graph or chart properties.

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D. Invoke Nodes

Invoke Nodes access the methods of an object Use the Invoke Node to perform actions, or methods, on an

application or VI Unlike the Property Node, a single Invoke Node executes

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p y gonly a single method on an application or VI

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4Invoke Nodes

To create an implicitly-linked Invoke Node, right-click the control and select CreateInvoke Node and choose a method

An example of a method that is common to all controls is

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the Reinitialize to Default method The Waveform Graph has the

method Export Image:

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Exercise 4-3: Front Panel Properties VI

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GOAL

Learn how to affect the attributes of a VI by using Property Nodes and Invoke Nodes.

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SummaryQuiz

1. For each of the following items, determine whether they operate on a VI class or a Control class.

a. Format and Precisionb. Blinking

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c. Reinitialize to Default Valued. Show Tool Bar

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SummaryQuiz Answer

1. For each of the following items, determine whether they operate on a VI class or a Control class.

a. Format and Precision: Controlb. Blinking: Control

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c. Reinitialize to Default Value: Controld. Show Tool Bar: VI

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SummaryQuiz

2. You have a GraphChart control refnum in a subVI. Which control references could you wire to the control refnum terminal of the subVI? (multiple answers)a. control reference of an XY Graph

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b. control reference of a Numeric Arrayc. control reference of a Waveform Chartd. control reference of a Boolean

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SummaryQuiz Answer

2. You have a GraphChart control refnum in a subVI. Which control references could you wire to the control refnum terminal of the subVI? (multiple answers)a. control reference of an XY Graph

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b. control reference of a Numeric Arrayc. control reference of a Waveform Chartd. control reference of a Boolean

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1TOPICS

Lesson 5Advanced File I/O Techniques

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A. File FormatsB. Binary FilesC. TDMS Files

A. File Formats

At their lowest level, all files written to your computers hard drive are a series of bits

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Binary

TDMSASCII

A. File FormatsASCII TDMS Direct Binary

Numeric Precision

Good Best Best

Share data

Best (Any program easily) Better (NI Programs easily)

Good (only with detailed metadata)

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Efficiency Good Best Best

Ideal Use Share data with other programs when file space and numeric precision are not important

Share data with programs whenstoring simple array data and metadata

Store numeric data compactly with ability to random access

B. Binary Files

Use Binary File functions to interact directly with a binary file

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B. Binary FilesBits/Bytes?

A bit is a single binary value Each bit is either on or off and is represented by a 1 or a 0

A byte is a series of 8 bits

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0 bit00000000 byte

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B. Binary FilesStoring Boolean Values

LabVIEW represents Boolean values as 8-bit values in a binary file

Eight zeroes represents False [00000000], and any other value represents True [00000001], [01000111],

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[11111111], and so on Files are divided into byte-sized chunks, making them

much easier to read and process

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2B. Binary FilesStoring Boolean Values

File ContentsMethod A00000001 00000001 00000000 00000001

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00000000 00000001

Method B00101011

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B. Binary FilesStoring Integers

Binary Value U8 Value00000000 000000001 100000010 2

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00000010 211111111 255

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B. Binary FilesStoring Integers

Multi-byte integers are broken into separate bytes and are stored in files in either little-endian or big-endian byte order

Using the Write to Binary File functions, you can choose whether you store your data in little-endian or big-endian

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format

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U32 Value Little-endian Value Big-endian Value

1 000000010000000000000000 00000000

00000000 0000000000000000 00000001

B. Binary FilesStoring Other Data Types

Strings are stored as a series of unsigned 8-bit integers, each of which has a value in the ASCII Character Code Equivalents Table This means that no difference exists between writing strings

ith th Bi Fil F ti d iti th ith th T t

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with the Binary File Functions and writing them with the Text File Functions

Clusters are best represented in binary files by using Datalog Files

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B. Binary FilesStoring Arrays

Arrays are represented as a sequential list of the elements Element representation depends upon the element type A header contains a 32-bit integer representing the size of

each dimension

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Example A 2D array with a header contains: row integer, column integer, then array data

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B. Binary FilesSequential/Random Access

Two methods of accessing data: Sequential AccessRead each item in order, starting at

the beginning of a file Random AccessAccess data at an arbitrary point within

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y pthe file

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3B. Binary FilesSequential Access

To sequentially access all of the data in a file, you can call the Get File Size function and use the result to calculate the number of items in the file, based upon the size of each item and the layout of the file

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You can then wire the number of items to the count terminal of the Read from Binary File function

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B. Binary FilesRandom Access

Use the Set Position VI to set the read offset to the point in the file you want to begin reading

The offset is in bytes; therefore, you must calculate the offset based upon the layout of the file

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B. Binary FilesDatalog

Datalog is a specific type of binary file, designed for storing a list of records to a file

Each record is represented by a cluster and can contain multiple pieces of data with any data type

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B. Binary FilesDatalog Random Access

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Exercise 5-1: Bitmap File Writer VI

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GOAL

Use Binary File I/O to write a file with a specified format.

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C. TDMS Files

TDMS Technical Data Management Streaming

Use TDMS files for the following purposes:

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Use TDMS files for the following purposes: To store test or measurement data To create a structure for grouping your data To store information about your data To read and write data at high speeds

4C. TDMS Files

TDMS file format: TDMS file Binary file (.tdms) that contains data and stores properties

about the data

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TDMS_Index file Binary index file (*.tdms_index) that provides consolidated

information on all the attributes and pointers in the TDMS file Speeds up access to the data while reading Automatically regenerated if lost

TDMS file format internal structure is publicly documented

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C. TDMS FilesData Hierarchy

Channel Stores measurement signals or raw data in a TDMS file Each channel can have properties describing the data The data stored in the signal is stored as binary data on disk to

di k d i ffi i

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conserve disk space and improve efficiency Channel Group Segment of a TDMS file that contains properties and one or more

channels Use channel groups to organize your data and to store information

that applies to multiple channels

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C. TDMS Files

Use TDMS Files in the following ways: Use the Write to Measurement File and Read from

Measurement File Express VIs Allow you to quickly save and retrieve data from TDMS format

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Very little control over your data grouping and properties Use the TDM Streaming API Set of functions for opening, writing to, reading from, and

closing TDMS files Allows you to organize your data into channel groups and

channels

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C. TDMS FilesTDM Streaming API

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C. TDMS FilesWrite Data

Streams data to the specified TDMS file Data subset to write is determined by group name and

channel name(s) inputs

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C. TDMS FilesRead Data

Reads the specified TDMS file and returns data from the specified channel and/or channel group

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5C. TDMS FilesSet Properties

Sets the properties of the TDMS file, channel group, or channel

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C. TDMS FilesGet Properties

Returns the properties of the TDMS file, channel group, or channel

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C. TDMS FilesFile Viewer

Opens TDMS file and presents the file data in the TDMS File Viewer dialog box

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C. TDMS FilesGrouping Data

Carefully consider the best way to group your data, because the data grouping can have a significant impact on both the execution speed and implementation complexity of writes and reads

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Things you should consider when choosing a grouping scheme include the original format of your data and how you want to process or view the data

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Exercise 5-2: TDMS Reader VI

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GOAL

Learn how to read data from a TDMS file.

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SummaryQuiz

1. You need to store test results and organize the data into descriptive groups. In the future, you need to efficiently view the test results by group. Which file storage format should you use?

a) Tab-delimited ASCIIb) Custom binary format

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b) Custom binary formatc) TDMSd) Datalog

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6SummaryQuiz Answer

1. You need to store test results and organize the data into descriptive groups. In the future, you need to efficiently view the test results by group. Which file storage format should you use?

a) Tab-delimited ASCIIb) Custom binary format

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b) Custom binary formatc) TDMSd) Datalog

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SummaryQuiz

2. You need to write a program which saves Portable Network Graphics (PNG) image files. Which file storage method should you use?

a) Storage file VIsb) Binary file functions

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b) Binary file functionsc) ASCII file VIsd) Datalog file VIs

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SummaryQuiz Answer

2. You need to write a program which saves Portable Network Graphics (PNG) image files. Which file storage method should you use?

a) Storage file VIsb) Binary file functions

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b) Binary file functionsc) ASCII file VIsd) Datalog file VIs

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SummaryQuiz

3. You need to store data that other engineers will later analyze with Microsoft Excel. Which file storage format should you use?

a) Tab-delimited ASCIIb) Custom binary formatc) TDMS

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c) TDMSd) Datalog

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SummaryQuiz Answer

3. You need to store data that other engineers will later analyze with Microsoft Excel. Which file storage format should you use?

a) Tab-delimited ASCIIb) Custom binary formatc) TDMS

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c) TDMSd) Datalog

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SummaryQuiz

a) 00001010 00000000 00000000

c) 00001010d) 01010000

4. Which of the following is a little-endian representation of an unsigned 32-bit integer (U32) with a value of 10?

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00000000 00000000

b) 00000000 00000000 00000000 00001010

00000000 00000000 00000000

7SummaryQuiz Answer

a) 00001010 00000000 00000000

c) 00001010d) 01010000

4. Which of the following is a little-endian representation of an unsigned 32-bit integer (U32) with a value of 10?

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00000000 00000000

b) 00000000 00000000 00000000 00001010

00000000 00000000 00000000

SummaryQuiz

5. True or False? You can use the Binary File Functions to read ASCII files.

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SummaryQuiz Answer

5. You can use the Binary File Functions to read ASCII files. True.

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SummaryQuiz

6. True or False? TDMS Files store properties only at the channel or channel group level.

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SummaryQuiz Answer

6. TDMS Files store properties only at the channel or channel group level. False.

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1TOPICS

Lesson 6Improving an Existing VI

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A. Refactoring Inherited CodeB. Typical Issues

A. Refactoring Inherited Code

Inherited VIs may be poorly designed, making it difficult to add features later in the life of the VIRefactoring: Process of redesigning software to make it more readable

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g gand maintainable so that the cost of change does not increase over time

Changes the internal structure of a VI to make it more readable and maintainable, without changing its observable behavior

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A. Refactoring vs. Performance Optimization

Changes that optimize the performance of a VI are not the same as refactoring

Refactoring specifically changes the internal structure of a VI to make it easier to read, understand, and maintain

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versus

A. When to Refactor

When you are adding a feature to a VI or debugging it There is value in a VI that functions, even if the block

diagram is not readable Good candidates for complete rewrites:

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p VIs that do not function VIs that satisfy only a small portion of your needs

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2B. Typical Issues

When you refactor to improve the block diagram, make small cosmetic changes before tackling larger issues

Improve Block Diagram

Test VI

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For example, it is easier to find duplicated code if the block diagram is well organized and the terminals are well labeled

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Add Features or Use VI

Is VI Acceptable?

Yes

No

B. Typical Issues

The following issues can make it difficult to work with an inherited VI: Too disorganized Uses incorrect object names and poor icons

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j p Uses unnecessary logic Has duplicated logic Does not use data flow programming Has complicated algorithms Is too big

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B. Typical Issues - Disorganized

The block diagram is too disorganized Move objects within the block diagram Create subVIs for sections of the VI that are

disorganized

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disorganized Place comments to improve readability

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B. Typical Issues

The block diagram uses incorrect object names and poor icons

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GoodBetter

Best

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B. Typical Issues

The block diagram uses unnecessary logic

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B. Typical Issues

The block diagram uses duplicate logic Refactor the VI by creating a subVI for the duplicated logic

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3B. Typical Issues

The block diagram does not use dataflow programming Replace Sequence structures with state machines if

appropriate Delete local variables and wire directly to controls or

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yindicators if possible

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B. Typical Issues

The block diagram has complicated algorithms

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Simplify:

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B. Typical Issues

The block diagram is too big (larger than the screen size) Refactor the VI to make it smaller Create subVIs for sections of code within the block diagram

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Exercise 6-1: Typical Issues

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GOAL

Concept ExerciseImprove an existing VI that is poorly designed.

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SummaryJob Aid

Use the following refactoring checklist to help determine if you should refactor a VI: The block diagram is too disorganized The block diagram contains incorrect object names and poor icons Th bl k di t i l i

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The block diagram contains unnecessary logic The block diagram contains duplicated logic The block diagram does not use dataflow programming The block diagram contains complicated algorithms The block diagram is too big

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1TOPICS

Lesson 7Creating and Distributing Applications

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A. LabVIEW Features for Managing Project DevelopmentB. Preparing the ApplicationC. Building the Application and Installer

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A. Managing Project Development

VI History Use the History window in each VI to display the

development history of the VI, including revision numbers The revision number starts at zero and increases

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incrementally every time you save the VI Record and track the changes you make to the VI in the

History window as you make them Select EditVI Revision History to display You also can print the revision history

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VI Hierarchy Displays a graphical representation of all open LabVIEW

projects and application instances, as well as the calling hierarchy for all VIs in memory, including type definitions

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and global variables

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Comparing VIs A utility to determine the differences between two VIs

loaded into the memory

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Exercise 7-1: LabVIEW Project Management Tools

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GOAL

Concept ExerciseExamine some of the built-in LabVIEW features for project management.

B. Preparing the Application

To create a professional, stand-alone application for your VIs, you must consider several programming issues: Use of outside code Use of relative path names

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p Quit LabVIEW function

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2C. Building the Application and Installer

Use Build Specifications in LabVIEW to create stand-alone applications and to create installers Stand-alone applicationsUse stand-alone applications to

provide other users with executable versions of VIs; this is

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useful when you want users to run VIs without installing the LabVIEW development system

InstallersUse installers to distribute stand-alone applications, shared libraries, and source distributions that you create with the Application Builder; you can include the LabVIEW Run-Time Engine

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C. Building the Application and Installer

System Requirements Applications that you create with Build Specifications

generally have the same system requirements as the LabVIEW development system used to create the VI or

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application Memory requirements vary depending on the size of the

application created

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Exercise 7-2: Creating an Application

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GOAL

Concept ExerciseCreate a stand-alone application with LabVIEW.

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Summary

The Application Builder enables you to create stand-alone applications and installers The Application Builder is available in the LabVIEW

Professional Development System, or as an add-on package

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Creating a professional, stand-alone application with your VIs involves four areas of understanding: The architecture of your application The programming issues particular to the application The application building process The installer building process

Continuing Your LabVIEW Education

Instructor Led Training LabVIEW Intermediate I: Learn about developing large

projects and event programming Hardware courses such as Data Acquisition and Signal

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q gProcessing

Online courses such as Machine Vision and LabVIEW Real-Time

Self-Paced: a variety of instructional packages and tools designed to educate you at your own pace

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Courses

New User

LabVIEW Basics I

LabVIEW Basics II

Experienced User

LabVIEW Intermediate I

LabVIEW Intermediate II

Advanced User

LabVIEW Advanced I

Skills learned: LabVIEW environment

navigation Basics application creation

using LabVIEW Basics of data acquisition and

Skills learned: Modular application

development Structured design and

development practices Inter-application

Skills learned: Large application design Advanced development

techniques Implementing multideveloper

projects

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Certifications

Certified LV Associate Developer Exam

Skills tested: LabVIEW environment

knowledge

Certified LabVIEW Developer Exam


development expertise

Certified LabVIEW Architect Exam


development mastery

Basics of data acquisition and instrument control

Inter-application communication and connectivity techniques

projects

3How To Learn More Out Of The Classroom

ni.com/support Access product manuals, KnowledgeBases, example code,

tutorials, application notes and discussion forums Request technical support

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Info-LabVIEW: www.info-labview.org Alliance Program: ni.com/alliance Publications: ni.com/reference/books/ Practice!

13 ni.com/training

THANK YOU!

Please complete the course survey and retrieve your course CD.

Lesson 1 - Common Design TechniquesLesson 2 - Communicating btn Multiple LoopsLesson 3 - Event ProgrammingLesson 4 - Controlling the User InterfaceLesson 5 - Advanced File IO TechniquesLesson 6 - Improving an Existing VILesson 7 - Creating and Distributing Executables

Documents

LabVIEW Basics II Slides