This document discusses virtual instruments. It begins with defining virtual instruments as instruments whose capabilities are determined by software running on general-purpose computers rather than dedicated hardware. The document then covers the history and evolution of virtual instruments from dedicated analog devices to computer-based instruments. It describes the typical architecture of a virtual instrument including sensor modules, processing modules, and output presentation. Finally, it provides an example virtual instrument developed in MATLAB and discusses advantages and disadvantages of virtual instruments.

1. VIRTUAL
INSTRUMENTS
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2. Group Members
• Rubab Shafique
• Barira Nashal
• Rimsha Arshad
• Warda Shadab
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3. CONTENT
 Introduction
 History
 Architecture
 Block diagram
 Example
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4. Virtual instrumentation is an
interdisciplinary field
It merges sensing, hardware and
software technologies.
 Used to create flexible and
sophisticated instruments for
control and monitoring
applications.
INTRODUCTION
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5. There are several definitions of a virtual
instrument available in the open literature.
 “An instrument whose general function and
capabilities are determined in software“.
“A virtual instrument is composed of some
specialized subunits, some general-purpose
Computers, some software, and a little know-
how”. 5

6. HISTORY
 The concept of was born in late 1970s.
 when microprocessor technology enabled a
machine's function to be more easily changed
by changing its software.
 The flexibility is possible as the capabilities of a
virtual instrument depend very little on
dedicated hardware.
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7. The first phase:
 It is represented by early "pure" analog
measurement devices, such as oscilloscopes etc.
 They were completely closed dedicated systems.
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8. The Second phase
o It is started in 1950s, as a result of demands from
the industrial control field.
o Instruments started to digitalize measured
signals, allowing digital processing of data.
The third phase
o Measuring instruments became computer based.
o They begun to include interfaces that enabled
communication between the instrument and the
computer.
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9. As a result, virtual instrumentation
made possible decrease in price of an
instrument.
 As the virtual instrument depends
very little on dedicated hardware, a
customer could now use his own
computer.
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10. VIRTUAL INSTRUMENT
ARCHITECTURE
A virtual instrument is composed of the following
blocks:
 Sensor module
 Processing Module
 Output
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11. SENSOR MODULE
 Performs signal conditioning.
(transforms it into a digital form for further
manipulation)
 The digital can be displayed, processed,
compared, stored in a database, or converted
back to analog form for further process control.
 It interfaces a virtual instrument to the external
analog world.
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12. SENSOR MODULE
 A sensor module principally consists of three
main parts:
 input
 the signal conditioning part
 the A/D converter
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13. SENSOR MODULE
INPUT
 Real World Data.
 According to the type of connection, sensor
interfaces can be classified as wired and wireless.
 Wired Interfaces are usually standard parallel
interfaces, such as General Purpose Interface Bus
 Wireless Interfaces are increasingly used because
of convenience.
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14. SIGNAL CONDITIONING
It is the techniques used to convert
immeasurable or unworkable signal
into useful or functional form.
Example:
 Some sensors give signal in micro volts which
needs to be amplified in order to use in the
circuit.
 If the signal has high amplitude then it needs to
be attenuated in order to use it. 14

15. ANALOG TO DIGITAL
CONVERTER
Real world data is then converted in
digital form by using ADC.
Analog data is converted in the form
which a computer can easily
understand.
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16. PROCESSING MODULE
 It allows flexible implementation of sophisticated
processing functions.
 A virtual instrument depends very little on
dedicated hardware, which principally does not
perform any complex processing.
 Functionality and appearance of the virtual
instrument may be completely changed utilizing
different processing functions.
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17. OUTPUT PRESENTATION
 Computer’s user interfaces are much
easier shaped.
 they are changed than conventional
instrument’s user interfaces.
 it is possible to employ more presentation
effects and to customize the interface for
each user.
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18. Input
Signal
Conditioning
ADCs
Processing Output
BLOCK DIAGRAM
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19. EXAMPLE
We have an example of a virtual instrument
developed in SITT
Instruments :
• Voltmeter
• Ammeter
• Ohmmeter
• Oscilloscope
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20. Applications
Main Form to Select
Virtual Instrument
Voltmeter
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21. Ammeter Ohmmeter
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22. Oscilloscope 22

23. FLOWCHART --
Initialize ADC
Take Input from the
real world
Computation and
Formulation
Transmit through
Serial Port
End
Start
Analog to Digital
Conversion
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24. FLOWCHART – MATLAB GUI
Start
Select
Instrument
If Ammeter
If Ohmmeter
If Voltmeter
If Oscilloscope
1 2 3 4
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25. Computation &
Conversion
Open GUI of Voltmeter
Receive Data
Print Result on Text Box
Is Hold
Button
Pressed?
Close Serial Port
Clear All
End
1
Yes
No
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26. Computation &
Conversion
Open GUI of Oscilloscope
Receive Data
Plot Data
Is Hold
Button
Pressed?
Close Serial Port
Clear All
End
2
Yes
No
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27. Computation &
Conversion
Open GUI of Ammeter
Receive Data
Print Result on Text Box
Is Hold
Button
Pressed?
Close Serial Port
Clear All
End
3
Yes
No
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28. Computation &
Conversion
Open GUI of Ohmmeter
Receive Data
Print Result on Text Box
Is Hold
Button
Pressed?
Close Serial Port
Clear All
End
4
Yes
No
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29. Advantages
• Lower cost of instrumentation
• Easy-to-use graphical user interface
• Portability between various computer platforms
• Increases the utility of computer
• Flexibility
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30. DISADVANTAGES
 Security
Sensitive information may be accessible to public
users.
 Power Consumption
VI demands that many devices run simultaneously
and can consume a lot of power. Each computer
will consume a large amount of power in addition
to any external hardware.
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