Chapter 9 Data Acquisition Measurement or generation of physical signals.

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Chapter 9Data AcquisitionMeasurement or
generation of physical signals.
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Data Acquisition in LabVIEW

• NI-DAQmx
• Next generation driver
• VIs for performing a task
• One set of VIs for all measurement types

• Traditional NI-DAQ
• Specific VIs for performing
• Analog Input
• Analog Output
• Digital I/O
• Counter operations

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DAQ System Componentsgt Sensor/Transducergt
Signal Conditioning Unitgt DAQ PCI Interface
Cardgt Computergt Software Analyze Display
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Phenomena TransducersTemperature
Thermocouple Resistance
Temperature Detectors (RTDs)
Integrated Circuit SensorLight
Vacuum Tube Photosensor Photoconductive
CellsSound MicrophoneForce Pressure
Strain Gauges Piezoelectric
Transducer Load CellsPosition
Optical Encoder
PotentiometersFluid Flow Head
Meters Rotational FlowmeterspH
pH electrodes
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Signal Conditioning Circuits gt Linearization gt
Excitation gt Isolation gt Filtering gt
Amplification
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Data Acquisition

• Data Acquisition (DAQ) Basics
• Connecting Signals
• Simple DAQ Application

M-SERIES
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NI USB-6009 14-bit Analog Inputs
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Signal Types Digital gt On-Off
gt Pulse Train Analog gt DC
gt Time-Domain gt Frequency-Domain

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Signal Information gt State gt Rate gt Level gt
Shape gt Frequency
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Signal Source Configuration gt Referenced
Singled-Ended RSE gt Non-referenced
Singled-Ended NRSE gt Differential
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Analog I/O Conversion Issues gt Resolution gt
Range gt Sampling Rate
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ADC Resolutiongt Number of bits used to
represent an analog signal.
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RangeMinimum Maximum analog signal levels that
the ADC can handle.
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Code Width VCW Range G x
2ResolutionThe smallest detectable voltage
change by a data acquisition board with gain G.
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Sampling Rate
Samples of an analog signal Discrete points in
time Sampling frequency number of samples per
second
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Sampling Rate
Aliased Signal
Adequately Sampled Signal