Data acquisition is the method in which signals are sampled. These signals result from the measurement of physical conditions in the real world. The acquired samples are then converted to form digital numeric values. These values are then used by computers for manipulation as required.
The acronyms DAQ along with DAS are used as the abbreviation for data acquisition systems. These systems are usually used for the conversion of waveforms that are of an analog nature into digital values which are then fed to computers for processing.
The main elements a data acquisition system are as follows.
The first one is the sensors. These sensors receive physical parameters as input which they convert into electrical signals.
The second element is the Signal conditioning circuitry. This circuitry receives the aforementioned sensor signals as input which they convert into an intermediate form which can later be converted into digital values.
The third element is the analog-to-digital converters. These converters receive the conditioned signals as input and convert them into digital values.
The applications of data acquisition are typically handled by various software programs. These programs are developed with the help of numerous programming languages categorized as general purpose which include Assembly, BASIC, C family, FORTRAN, Java, Lisp and Pascal. The data acquisition systems which are of a stand-alone nature are usually referred to as data loggers.
The following methodology is followed by the data acquisition systems.
No matter what the type of the physical property is, that particular state needs to be converted into a standardized form which can then be sampled. Sensors are the devices that are used to carry out these conversions. These are the devices which convert the desired physical property into electrical signals.
The interface that works between the generated electrical signals and a computer is called DAQ hardware. It can be of either a modular form which are connected with ports of the computer or of a card form which are connected to slots situated in the motherboard.
Without DAQ drivers, the hardware cannot work with the computer. It provides an API for the development of applications for users while itself performing low-level reading and writing operations on the registers.
The input devices include a 3D scanner and converters (analog to digital and time to digital).
The hardware may come with a specialized DAQ software. Large scale data acquisition systems are developed by the use of various software tools including EPICS. Numerous other programming environments are also made use of. These include ladder logic, Visual C++, Visual Basic, LabVIEW, and MATLAB.