Programming Data Acquisition Systems Using LabView

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Programming Data Acquisition Systems Using LabView

• MECE 3320
• Measurements and Instrumentation
• Stephen W. Crown Ph.D.

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Environment(Panel Window)
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Environment(Diagram Window)
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Data Structure

• Integer (1)
• Real (1.3546900)
• String (hello)
• Boolean (true)
• Array (1,2,3,4,5)
• Cluster (1.354,1,2,3,hello)

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Data Structure

• Integer (1)
• Real (1.3546900)
• String (hello)
• Boolean (true)
• Array (1,2,3,4,5)
• Cluster (1.354,1,2,3,hello)

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Program Structure (IO)

• Input / Control
• Button
• Digital
• Text
• Output /Indicator
• Digital
• Graph
• Text

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Program Structure (Flow)

• Sequence
• Frames executed in order
• Sequence local used to pass values to other
  frames
• Case
• True/False
• Or Text
• For Loop
• For i0 to N-1
• Shift register used to pass values to next
  iteration
• Indexing (enabled of disabled)
• While Loop
• Loops while control is true
• Equation Node

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Subroutines

• Programs can be saved as subroutines that may be
  executed in other programs.
• Subroutine Icon
• Input Variables
• Output Variables

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Examples

• Interest Rate

• Sampling Rate

• Numerical Integration

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Appendix
Measurements and Instrumentation

• The following slides are linked to the lecture
  notes and provide greater detail or examples on
  specific topics.

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Interest Rate

• An investment is compounded yearly at a fixed
  interest rate. The VI calculates the value at
  the end of a selected period.

sample.vi
Appendix
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Sampling Rate

• A minimum of two samples per cycle are required
  to capture a signal. This VI shows the effect of
  varying the sample rate and does numerical
  integration of the sampled signal.

sample.vi
Appendix
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Numerical Integration

• A function may be integrated numerically by
  evaluating the function at even step intervals
  and approximating the area under the curve with
  the area of the stepwise function. The first VI
  calculates the integral using a formula node.
  The second VI uses an evaluated formula node.

Sample.vi Sample_2
Appendix
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Numerical Integration
Sample.vi
Appendix