Catalog / LabVIEW Cheat Sheet
LabVIEW Cheat Sheet
A comprehensive cheat sheet covering essential LabVIEW concepts, functions, and development practices.
LabVIEW Basics
Core Concepts
Virtual Instrument (VI): The fundamental building block in LabVIEW, representing a program with a front panel, block diagram, and icon/connector pane. |
Front Panel: The user interface of a VI, containing controls (inputs) and indicators (outputs). |
Block Diagram: The graphical code of a VI, where you connect functions, structures, and data to perform operations. |
Controls: Input elements on the front panel (e.g., numeric controls, buttons, strings). |
Indicators: Output elements on the front panel (e.g., graphs, numeric indicators, LEDs). |
Dataflow Programming: LabVIEW executes code based on the availability of data, not on a sequential order. |
Data Types
Numeric: |
Integers (I8, I16, I32, I64), Floating-point (SGL, DBL, EXT), Complex. |
Boolean: |
TRUE or FALSE values. |
String: |
Textual data. |
Array: |
Collection of elements of the same data type. |
Cluster: |
Collection of elements of different data types (similar to a struct). |
Path: |
File or directory path. |
Basic Operations
Right-click on the Block Diagram to access functions, structures, and VIs. |
Use the Wiring tool to connect terminals and pass data between nodes. |
Use the Execution Highlighting tool (light bulb icon) to visualize data flow during execution. |
Use the Probe tool to inspect data values at specific points in the Block Diagram. |
Use the Breakpoint tool to pause execution at specific points in the Block Diagram. |
Structures and Functions
Structures
While Loop: |
Executes code repeatedly until a condition is met. |
For Loop: |
Executes code a specified number of times. |
Case Structure: |
Executes different code sections based on an input value. |
Sequence Structure: |
Executes code in a sequential order (less common in modern LabVIEW). |
Event Structure: |
Handles user interface events, such as button clicks or value changes. |
Common Functions
Numeric Functions: |
Add, Subtract, Multiply, Divide, Trigonometric functions, etc. |
String Functions: |
Concatenate Strings, String Length, Substring, String to Number conversion, etc. |
Array Functions: |
Array Size, Index Array, Replace Array Subset, Build Array, etc. |
File I/O Functions: |
Read from File, Write to File, Create Directory, Delete File, etc. |
Timing Functions: |
Wait, Wait Until Next ms Multiple, Get Date/Time, etc. |
Dialog & User Interface: |
One Button Dialog, Two Button Dialog, Message to User, etc. |
Error Handling
Always handle errors in LabVIEW to prevent unexpected program termination. |
Use the Error In and Error Out clusters to pass error information between nodes. |
Use the ‘Simple Error Handler’ VI for basic error handling. |
Consider using more advanced error handling techniques for complex applications, such as error handling case structures. |
Data Acquisition (DAQ)
DAQ Basics
LabVIEW is widely used for data acquisition and instrument control. |
Use the DAQmx VIs to interface with National Instruments DAQ hardware. |
Common DAQ tasks include analog input, analog output, digital input, and digital output. |
DAQmx VIs
DAQmx Create Virtual Channel: |
Creates a virtual channel for a specific DAQ task. |
DAQmx Timing: |
Configures the timing of the DAQ task (e.g., sample rate, number of samples). |
DAQmx Start Task: |
Starts the DAQ task. |
DAQmx Read: |
Reads data from the DAQ device. |
DAQmx Write: |
Writes data to the DAQ device. |
DAQmx Stop Task: |
Stops the DAQ task. |
DAQmx Clear Task: |
Clears the DAQ task and releases resources. |
Example DAQ Sequence
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Advanced Techniques
State Machines
State machines are a common design pattern for creating complex applications in LabVIEW. |
Use a While Loop and Case Structure to implement a state machine. |
Each state represents a specific action or behavior of the application. |
Transitions between states are triggered by events or conditions. |
Queues
Queues: |
Used for passing data between parallel loops in LabVIEW. |
Enqueue: |
Adds data to the end of the queue. |
Dequeue: |
Retrieves data from the front of the queue. |
Obtain Queue: |
Creates a new queue. |
Release Queue: |
Destroys a queue and releases its resources. |
Property Nodes and Invoke Nodes
Property Nodes: Used to get or set the properties of front panel objects or other LabVIEW objects. |
Invoke Nodes: Used to call methods on LabVIEW objects. |
These nodes provide programmatic control over the behavior and appearance of VIs. |