LabVIEW Introduction
Alan Jennings
Programming in general
The Data:
MATLAB, C, Java
• Variables, stack
LabVIEW, Simulink, FPGA
• Connections (wires)
– 1 Output,
– Many inputs
Excel
• Predefined by cells
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Programming in general
The Instructions:
Inputs and outputs
MATLAB, C, Java, Excel
• function, operator, method
• [m,b]= linearfit(x, 3*x+4)
LabVIEW, Simulink, FPGA
• Blocks with inputs and
outputs
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Programming in general
Structure:
Order of execution
MATLAB, C, Java, Excel
• Sequential: Line after line
• Routing commands
–Loops, conditional, break, goto,
LabVIEW,
• As data is available
• Loops
Simulink, FPGA
• Blocks with inputs and outputs
– FPGA physically simultaneous
– Simulink numerically simultaneous
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Setting up a LabVIEW Program
• Front Panel
– Controls: how the user controls the program
– Indicators: Displaying results
– Function Wiring
for using your VI’s by other VI’s
• Block Diagram
– Data: All controls and indicators, Also constants
– Doing something: Add functions
– Control what happens: Add structure
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LabVIEW Components
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• Inputs:
– Number,
– File names,
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Front Panel
Array,
Matrix
Categories
LabVIEW Components
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• Inputs:
– Binary
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Front Panel
More Numeric
LabVIEW Components
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Icons: little to no description
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Function Blocks
Icons
Blocks
Default values
Using Context help
Hover over icons, blocks or wires to see
what it is and the different signals
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LabVIEW Components
Blocks expand to show all
possible signals
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Loops
• For Loop
– Indexing over arrays
• While Loop
– Wait for an event to stop
(such as user or trigger)
– Feedback block
• Sequence loops
– Specify execution order
– Important for local variables
• Case loops
– Conditional Execution
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LabVIEW Components
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Data Types
• Waveforms
– Values, to, Sample frequency
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Arrays (column)
2d Arrays
Clusters (similar to structures)
Objects (typical for controlling DAQ’s, etc)
Easiest thing to do is use the port and create
constant to see
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LabVIEW Components
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Ex: Finding Largest Value
• Generate Data
• Compare each value to current best
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Programming Examples
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Ex: Finding Largest Value
• Generate Data
– Use Gaussian generation block
• Set standard deviation and number of samples
– Convert data type
• Compare each value to current best
– Initialize the current largest value
– Use `for’ loop to index over signal
– Change selection based on logic test
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Generate Data
1. Set standard deviation and number of samples
2. Use Gaussian generation block
3. Convert data type
Ex: Finding Largest Value
Compare each value to current best
4. Initialize the current largest value
5. Use `for’ loop to index over signal
6. Change selection based on logic test
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Generate Data
Ex: Finding Largest Value
These are controlled by
the front panel
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1. Set standard deviation and number of samples
2. Use Gaussian generation block
3. Convert data type
Compare each value to current best
4. Initialize the current largest value
5. Use `for’ loop to index over signal
6. Change selection based on logic test
Programming Examples
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Generate Data
Ex: Finding Largest Value
1. Set standard deviation and number of samples
2. Use Gaussian generation block
3. Convert data type
Compare each value to current best
4. Initialize the current largest value
5. Use `for’ loop to index over signal
6. Change selection based on logic test
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Generate Data
Ex: Finding Largest Value
1. Set standard deviation and number of samples
2. Use Gaussian generation block
3. Convert data type
Compare each value to current best
To pull of individual values,
convert to an array
4. Initialize the current largest value
5. Use `for’ loop to index over signal
6. Change selection based on logic test
Other blocks may
require other formats
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Generate Data
Ex: Finding Largest Value
1. Set standard deviation and number of samples
2. Use Gaussian generation block
3. Convert data type
Compare each value to current best
4. Initialize the current largest value
5. Use `for’ loop to index over signal
6. Change selection based on logic test
Pull the 0 index as the
initial condition
Use it to initialize
feedback block
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Generate Data
1. Set standard deviation and number of samples
2. Use Gaussian generation block
3. Convert data type
Ex: Finding Largest Value
Compare each value to current best
4. Initialize the current largest value
5. Use `for’ loop to index over signal
6. Change selection based on logic test
Indexed (pulls each value)
Non-Indexed
(returns last)
Non-Indexed
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Programming Examples
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Generate Data
Ex: Finding Largest Value
1. Set standard deviation and number of samples
2. Use Gaussian generation block
3. Convert data type
Compare each value to current best
4. Initialize the current largest value
5. Use `for’ loop to index over signal
6. Change selection based on logic test
Flow if current largest is largest
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Flow if current value is largest
Programming Examples
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Ex: Approximating Human Control
• Dynamic System
• Generate disturbance,
– Or possibly tracking path
• Find the command as function of
error and its derivative
• Do linear fit to find average gain values
• Find how well the gains describe behavior
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Programming Examples
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Ex: Approximating Human Control
• TankControl.vi
• Simple Tank Control (loss proportion to height)
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Programming Examples
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Ex: Approximating Human Control
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TankControl_2.vi
Include maximum time
Do linear estimation of control policy
Use local variables
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Programming Examples
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Ex: Approximating Human Control
• Doesn’t Work!
• Zeros for linear fit
first time
• Troubleshooting
planar fit error
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Programming Examples
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Ex: Approximating Human Control
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TankControl_3.vi
Add 2D and 3D graphs
Add control for set point
Add start button
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I didn’t say the graphs looked good.
Sequence loop separates activation
Data Type conversions
to use graphics
Need to separate the array
and bundle x & y as pairs
Other Program Challenges
• Programming Problems:
• Finding prime numbers
• Binary to dec converter
• tausiq.wordpress.com/2009/07/27/push-ups-with-blaze/
• Rock, paper, scissor tournament
• Currency Converter
• Verifying 8 Queens
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