LabVIEW Introduction Alan Jennings. Programming in general The Data: MATLAB, C, Java Variables, stack LabVIEW, Simulink, FPGA Connections (wires) – 1

LabVIEW Introduction

Alan Jennings

Programming in general

The Data:MATLAB, C, Java• Variables, stackLabVIEW, Simulink, FPGA• Connections (wires)

– 1 Output, – Many inputs

Excel• Predefined by cells

3/28/2012 Programming comparison 2

Programming in generalThe 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


Programming in generalStructure: Order of executionMATLAB, C, Java, Excel• Sequential: Line after line• Routing commands

–Loops, conditional, break, goto, LabVIEW, • As data is available• LoopsSimulink, FPGA• Blocks with inputs and outputs

–FPGA physically simultaneous–Simulink numerically simultaneous


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

3/28/2012 LabVIEW Components 5

Front Panel• Inputs: – Number, Array, Matrix


– File names, Categories

Front Panel• Inputs: – Binary More Numeric


Function Blocks• Icons • Blocks• Default values• Using Context help


Blocks expand to show all possible signals

Icons: little to no description

Hover over icons, blocks or wires to see what it is and the different signals

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


Data Types

• Waveforms– Values, to, Sample frequency

• 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 see3/28/2012 LabVIEW Components 10

Ex: Finding Largest Value

• Generate Data• Compare each value to current best

3/28/2012 Programming Examples 11


• 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


Ex: Finding Largest ValueGenerate Data

1. Set standard deviation and number of samples2. Use Gaussian generation block3. Convert data type

Compare each value to current best4. Initialize the current largest value5. Use `for’ loop to index over signal6. Change selection based on logic test


12 3 4

3

5

4

6





These are controlled by the front panel









To pull of individual values, convert to an array

Other blocks may require other formats



Pull the 0 index as the initial condition

Use it to initialize feedback block

Generate Data1. Set standard deviation and number of samples2. Use Gaussian generation block3. Convert data type




Indexed (pulls each value)

Non-Indexed

Non-Indexed (returns last)





Flow if current largest is largest Flow if current value is largest



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


Ex: Approximating Human Control• TankControl.vi• Simple Tank Control (loss proportion to height)


Ex: Approximating Human Control• TankControl_2.vi• Include maximum time• Do linear estimation of control policy• Use local variables


Ex: Approximating Human Control

• Doesn’t Work!• Zeros for linear fit

first time• Troubleshooting

planar fit error


Ex: Approximating Human Control• TankControl_3.vi• Add 2D and 3D graphs• Add control for set point• Add start button


I didn’t say the graphs looked good. I didn’t say the graphs looked good.

Sequence loop separates activationSequence loop separates activation

Data Type conversions to use graphicsData Type conversions to use graphics

Need to separate the array and bundle x & y as pairsNeed 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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LabVIEW Introduction Alan Jennings. Programming in general The Data: MATLAB, C, Java Variables, stack LabVIEW, Simulink, FPGA Connections (wires) – 1