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Virtual Instrument
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.
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Virtual Instrument
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- 2. Group Members • RubabShafique • Barira Nashal • Rimsha Arshad • Warda Shadab 2
- 3. CONTENT Introduction History Architecture Block diagram Example 3
- 4. Virtual instrumentation isan interdisciplinary field It merges sensing, hardware and software technologies. Used to create flexible and sophisticated instruments for control and monitoring applications. INTRODUCTION 4
- 5. There are severaldefinitions 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 conceptof 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. 6
- 7. The first phase: It is represented by early "pure" analog measurement devices, such as oscilloscopes etc. They were completely closed dedicated systems. 7
- 8. The Second phase oIt 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. 8
- 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. 9
- 10. VIRTUAL INSTRUMENT ARCHITECTURE A virtualinstrument is composed of the following blocks: Sensor module Processing Module Output 10
- 11. SENSOR MODULE Performssignal 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. 11
- 12. SENSOR MODULE Asensor module principally consists of three main parts: input the signal conditioning part the A/D converter 12
- 13. SENSOR MODULE INPUT RealWorld 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. 13
- 14. SIGNAL CONDITIONING It isthe 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 Realworld data is then converted in digital form by using ADC. Analog data is converted in the form which a computer can easily understand. 15
- 16. PROCESSING MODULE Itallows 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. 16
- 17. OUTPUT PRESENTATION Computer’suser 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. 17
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- 19. EXAMPLE We have anexample of a virtual instrument developed in SITT Instruments : • Voltmeter • Ammeter • Ohmmeter • Oscilloscope 19
- 20. Applications Main Form toSelect Virtual Instrument Voltmeter 20
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- 23. FLOWCHART -- Initialize ADC TakeInput from the real world Computation and Formulation Transmit through Serial Port End Start Analog to Digital Conversion 23
- 24. FLOWCHART – MATLABGUI Start Select Instrument If Ammeter If Ohmmeter If Voltmeter If Oscilloscope 1 2 3 4 24
- 25. Computation & Conversion Open GUIof Voltmeter Receive Data Print Result on Text Box Is Hold Button Pressed? Close Serial Port Clear All End 1 Yes No 25
- 26. Computation & Conversion Open GUIof Oscilloscope Receive Data Plot Data Is Hold Button Pressed? Close Serial Port Clear All End 2 Yes No 26
- 27. Computation & Conversion Open GUIof Ammeter Receive Data Print Result on Text Box Is Hold Button Pressed? Close Serial Port Clear All End 3 Yes No 27
- 28. Computation & Conversion Open GUIof Ohmmeter Receive Data Print Result on Text Box Is Hold Button Pressed? Close Serial Port Clear All End 4 Yes No 28
- 29. Advantages • Lower costof instrumentation • Easy-to-use graphical user interface • Portability between various computer platforms • Increases the utility of computer • Flexibility 29
- 30. DISADVANTAGES Security Sensitive informationmay 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. 30
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