Www.natinst.com Measurement Fundamentals Rajesh Vaidya DAQ Software Engineer Wed 10:15a, 12:45p, and...

www.natinst.comwww.natinst.com

Measurement Fundamentals

Rajesh Vaidya

DAQ Software Engineer

Wed 10:15a, 12:45p, and 3:30p

Colorado (6A)


Presentation OutlinePresentation Outline

Design considerations Hardware and software selection Demo of sample measurement systems Factors affecting accuracy Parting thoughts

Design considerations Hardware and software selection Demo of sample measurement systems Factors affecting accuracy Parting thoughts


Design ConsiderationsDesign Considerations

Define system requirements• Classify application based on signal types

(AI/AO/DIO/CTR or combination)• Number of I/O channels• Speed/accuracy • Signal conditioning requirements• Portability• Scalability • Backward compatibility with existing systems

Define system requirements• Classify application based on signal types

(AI/AO/DIO/CTR or combination)• Number of I/O channels• Speed/accuracy • Signal conditioning requirements• Portability• Scalability • Backward compatibility with existing systems


Measurement System ComponentsMeasurement System Components

Physical phenomena(Temperature,pressure, etc.)

Transducer

Voltagecurrent,

resistance

Signalconditioning

PC with data acquisition

Device +

Measurement software

wiring


Signal Types and Conditioning RequirementsSignal Types and Conditioning Requirements


Defining Requirements (cont’d.)Defining Requirements (cont’d.)

Number of I/O channels• Low

– DAQ board

• Medium – Higher channel DAQ board– Multiple DAQ boards

• High– SCXI-based system

Number of I/O channels• Low

– DAQ board

• Medium – Higher channel DAQ board– Multiple DAQ boards

• High– SCXI-based system


Requirements (cont’d.)Requirements (cont’d.)

0

5

10

15

20

25

30

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

Speed (Samples/sec)

Ac

cu

rac

y (B

its

)

0

5

10

15

20

25

30

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

Speed (Samples/sec)

Ac

cu

rac

y (B

its

) PC-4350

PCI-603x

PC-611x

PCI-5112

Speed vs. Accuracy


Additional ConsiderationsAdditional Considerations

Multifunction DAQ board vs. computer-based instrument

Does your system need portability?• PCMCIA, PCI, AT, PXI, USB, FireWire, serial,

parallel

Multifunction DAQ board vs. computer-based instrument

Does your system need portability?• PCMCIA, PCI, AT, PXI, USB, FireWire, serial,

parallel


Software/Programming Interface Software/Programming Interface

Interactive interface (ready to run)• VirtualBench

Programmatic interface LabVIEW

• LabWindows/CVI• C++/Visual Basic/Delphi• ActiveX controls

Interactive interface (ready to run)• VirtualBench

Programmatic interface LabVIEW

• LabWindows/CVI• C++/Visual Basic/Delphi• ActiveX controls


DAQ Designer 99 DAQ Designer 99

Online system configuration tool

www.natinst.com/daq/ddonline.htm

Online system configuration tool

www.natinst.com/daq/ddonline.htm


Demo VirtualBench and LabVIEW InterfaceDemo VirtualBench and LabVIEW Interface


Making Accurate Measurements Making Accurate Measurements

Signal resolution Grounding issues Line noise Environmental factors Calibration Source impedance

Signal resolution Grounding issues Line noise Environmental factors Calibration Source impedance


Accuracy Issues (cont’d.) Accuracy Issues (cont’d.)

Signal resolution• Type of A/D Converter – 12-bit vs. 16-bit• Gain setting

Grounding issues• Differential• Reference single ended• Non-Referenced single ended

Signal resolution• Type of A/D Converter – 12-bit vs. 16-bit• Gain setting

Grounding issues• Differential• Reference single ended• Non-Referenced single ended


Accuracy Issues (cont’d.)Accuracy Issues (cont’d.) Line noise

• Use filtering to eliminate 50-60 Hz line noise

Environmental factors• Use shielded cables• Distance system from noise sources

Calibration• Perform regular calibration

Source impedance• High impedance sources can cause problems

Line noise• Use filtering to eliminate 50-60 Hz line noise

Environmental factors• Use shielded cables• Distance system from noise sources

Calibration• Perform regular calibration

Source impedance• High impedance sources can cause problems


Demo – Temperature MeasurementDemo – Temperature Measurement


Demo – Frequency MeasurementDemo – Frequency Measurement


Deploy the SystemDeploy the System

Stand-alone systems “Executable” versions for clients Part of networked DAQ system

• DataSocket• RDA• VI Server

Stand-alone systems “Executable” versions for clients Part of networked DAQ system

• DataSocket• RDA• VI Server


Measure Anything / Automate EverythingMeasure Anything / Automate Everything

PC-based measurement systems offer:• Superior performance• Lower cost• Better integration• Faster development cycles• Distributed measurement capabilities

PC-based measurement systems offer:• Superior performance• Lower cost• Better integration• Faster development cycles• Distributed measurement capabilities

Www.natinst.com Measurement Fundamentals Rajesh Vaidya DAQ Software Engineer Wed 10:15a, 12:45p, and...

Documents

Transcript of Www.natinst.com Measurement Fundamentals Rajesh Vaidya DAQ Software Engineer Wed 10:15a, 12:45p, and...