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A
virtual instrument in principle is a computer based software driven instrument
for test, measurement or process control applications. Virtual instruments are
thus composed of layers of software and hardware having a virtual control panel
that only appears on a computer display.
In virtual instrumentation systems
the appearance of real instruments and measurement workbenches are mimicked so
that they resemble the interfaces of their real counterparts. Instead of conventional
text-based procedural programming languages where syntax and punctuations are
sensitive aspects of a program, visual or graphics-based programming is ideal
for virtual instrumentation. Different DAQ (Data Acquisition) Cards are available
which are interfaced with our PC. Data Acquisition devices combine data acquisition
with the processing power of a computer.
With DAQ devices, the hardware converts
the incoming signal into a digital signal that is sent to the computer. The computer
receives raw data. Software takes the raw data and presents it in a form the user
can understand. Software manipulates the data so it can appear in a graph or chart
or in a file for report. The software also controls the DAQ system, telling the
DAQ device when to acquire data, as well as from which channels to acquire data.
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