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 the 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, then conditioning the electrical signal which can then be acquired by data acquisition hardware.
Disclaimer: This was my B.Tech. Major project that I did with my friends, as a part of our course curriculum. AT that time, I did not have a lot of ideas (i.e., using microcontrollers) to build embedded projects, but I was good at soldering electronic components on general-purpose PCB. I had found somewhere on the internet about controlling a piece of equipment through the printer port of a pc. Yes, at that time PCs had a 25 pin parallel printer port (line printer terminal or LPT for short). I extended that Idea to design/build a PCB to use all eight channels (or "bits") in the parallel LPT port. Since I was going to use all 8-bits of the LPT port to control 8 pieces of electrical equipments, I thought why not use the other 8 input bits to detect if something was ON/OFF. So, I did just that. The Inputs were protected by transceiver ICs and electromechanical relays, whereas the outputs were protected by buffer ICs and optically isolated electromechanical relays. Both the Input and output boards had eight LEDs each to indicate if a bit was ON/OFF. I used two different software to communicate with the interface boards, both of which I just downloaded from the internet. They directly access the bits of the LPT port through low-level drivers in DOS mode or from the "C" program through the appropriate library. Now that I think of it, I could probably make the software myself from C with my current knowledge.