10-06-2017, 07:01 AM
Abstract
Data acquisition is the sampling of the real world to generate data that can be manipulated by a computer. Sometimes abbreviated DAQ or DAS, data acquisition typically involves acquisition of signals and waveforms and processing the signals to obtain desired information. The components of data acquisition systems include appropriate sensors that convert any measurement parameter to an electrical signal, which is acquired by data acquisition hardware.DAQ hardware is what usually interfaces between the signal and a PC. It could be in the form of modules that can be connected to the computer's ports (parallel, serial, USB, etc..) or cards connected to slots (PCI, ISA) in the mother board. DAQ-cards often contain multiple components (multiplexer, ADC, DAC, TTL-IO, high speed timers, RAM). These are accessible via a bus by a micro controller, which can run small programs. The controller is more flexible than a hard wired logic, yet cheaper than a CPU so that it is alright to block it with simple polling loopsDAQ software is needed in order for the DAQ Hardware to work with a PC. This can come in at least three flavors: applications that register directly from the hardware, low-level software driver (usually packaged with the DAQ hardware) to allow developing higher level applications to register data coming from the hardware and off-the-shelf applications. Driver software that usually comes with the DAQ hardware or from other vendors, allows the operating system to recognize the DAQ hardware and programs to access the signals being read by the DAQ hardware. A good driver offers high and low level access. So one would start out with the high level solutions offered and improves down to assembly instructions in time critical or exotic applications.