24-08-2013, 03:02 PM
Data Acquisition Systems
Acquisition Systems[.ppt (Size: 328.5 KB / Downloads: 16)
INTRODUCTION
DAQ (Data Acquisition) is defined as the process of taking a real-world signal as input, such as a voltage or current any electrical input, into the computer, for processing, analysis, storage or other data manipulation or conditioning. Buildings of DAQ system that actually does-
• Transducers and actuators
• Signal conditioning
• Data acquisition and control hardware
• Computer systems software
Transducers and Actuators
A transducer converts temperature, pressure, level, length, position, etc. into voltage, current, frequency, pulses or other signals.
An actuator is a device that activates process control equipment by using electrical power. For example, a valve actuator opens and closes a valve to control fluid rate.
Signal Conditioning
Signal conditioning circuits improve the quality of signals generated by transducers before they are converted into digital signals by the PC's data-acquisition hardware.
Examples of signal conditioning are signal scaling, amplification, linearization, cold-junction compensation, filtering, attenuation, excitation, common-mode rejection, and so on.
Analog Outputs (D/A)
The opposite of analog to digital conversion is digital to analog (D/A) conversion. This operation converts digital information into analog voltage or current. D/A devices allow the computer to control real-world events.
Analog outputs can also be used to generate waveforms. In this case, the device behaves as a function generator.
Data Acquisition Software
It can be the most critical factor in obtaining reliable, high performance operation.
Transforms the PC and DAQ hardware into a complete DAQ, analysis, and display system.
Different alternatives:
Programmable software.
Data acquisition software packages.