Chapter 2 LabVIEW
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Transcript of Chapter 2 LabVIEW
Minhhuy Le, EEE, Phenikaa Uni.
Chapter 21. LabVIEW Programming Development
2. Loops and Waveform Graphs
3. Data Files and Character Strings
4. Important Programming Structures: cases, shift registers...
Outline
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Minhhuy Le, EEE, Phenikaa Uni.
Outline
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Sensor DAQ Algorithm
Display
Save data
DAQ Output
Load data
PC
Minhhuy Le, EEE, Phenikaa Uni.
2.2 Loops and Waveform Graphs
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While loop
While loops
Condition met?
Code
End
Repeat (code)Until condition met;End;
While (condition met):{Code;}
Flowchart Pseudo Code C code
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While loops
Right-click on Block diagram-> Structures-> While loop
2.2 Loops and Waveform Graphs While loop
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While loops
Left-mouse drag & drop While loopError ???
No Stop-condition
Iteration
2.2 Loops and Waveform Graphs While loop
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Example: generate a random value in range (0,1) and offset by a “Center numeric” valueBoolean to control stop of while loop
2.2 Loops and Waveform Graphs While loop
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While loop
Right-click on Block diagram-> Structures-> For loop
2.2 Loops and Waveform Graphs While loop
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For loop
Example: generate a random value in range (0,1) and offset by a “Center numeric” value
Numeric: number of loops“Loops” = “Numeric” - 1
2.2 Loops and Waveform Graphs For loop
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While loop <-> For loop
Right-click on the boundary of loop-> Replace with For Loop
2.2 Loops and Waveform Graphs For loop
Convert While -> For loop
Wire: error
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Tunnel Modes:Last valueIndexingConcatenatingConditional
2.2 Loops and Waveform Graphs For loop
Right-click
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Tunnel Modes:Last valueIndexingConcatenatingConditional
2.2 Loops and Waveform Graphs For loop
Last value
Indexing: build array
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Timing:Tick Count: current time in ms
Wait: stop execution in an amount of timeWait until next ms
Multiple: Execute loop in an interval time
2.2 Loops and Waveform Graphs Timing
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Timing:Tick Count: current time in ms
Wait: stop execution in an amount of timeWait until next ms
Multiple: Execute loop in an interval time
2.2 Loops and Waveform Graphs Timing
Interval = 100ms
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Case structure = If, else
2.2 Loops and Waveform Graphs Case structure
True
False
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Waveform graphs:Right click on Front panel -> Modern -> GraphChartGraphXY Graph3D Graphs...
2.2 Loops and Waveform Graphs Waveform graphs
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Waveform Chart: Update by a single value
2.2 Loops and Waveform Graphs Waveform graphs
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Waveform Chart: Click on Waveform graph variable on Block diagram - > Ctrl + H -> Show Context Help -> Input data to the graph
2.2 Loops and Waveform Graphs Waveform graphs
Ctrl + H
N points-> N Charts
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Waveform Chart: Plot legend can be adjust plot styles, color, line style, line width ....
2.2 Loops and Waveform Graphs Waveform graphs
Plot legend Multiple plot -> multiple legends
Plot properties
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Waveform Graph: Input an array
2.2 Loops and Waveform Graphs Waveform graphs
Single value1D array
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XY Graph: Input 2 arrays: x array, y array -> BundleMultiple bundles -> Multiple XY Graphs
2.2 Loops and Waveform Graphs Waveform graphs
Bundle
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Data types on Wires:Different data types cannot be wired
2.2 Loops and Waveform Graphs Waveform graphs
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3D Graphs: surface, mesh, surface graph ...
2.2 Loops and Waveform Graphs 3D graphs
Plot helper-> Input data
Plot variable: display
Empty 3D surface graph
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2.2 Loops and Waveform Graphs 3D graphs
3D Graphs: Example
Data generationPlot helper
Display
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2.2 Loops and Waveform Graphs 3D graphs
Find examples:On an VI -> Help-> Find Examples...-> Enter keyword(s)
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2.2 Loops and Waveform Graphs 3D graphs
Graph example coding: x = a*sin(2*pi*f*t + phi) + b
Sin waveform generator
Waveform graph
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2.2 Loops and Waveform Graphs Summary
Summary:• For & While loops• Case structure (if/else)• Waveform chart• Waveform graph• XY graph• 3D Graphs
Homework: x = a*cos(2*pi*f*t - phi) + b• Waveform chart in while/for loop• XY graph: x-axis: time t; y-axis: x value
