Data Acquisition System

1. REDIRECT Data acquisition system

Data acquisition system (DAS) refers to a computer system that collect the data from plant such as temperature, flow, pressure, etc, and then processes the data as it is programmed to do so such as display, store, print report, etc. Since most of the data collected are originally analog signal and the computer is a digital system an analog to digital converter must be used in the system. A data acquisition system the consists of

 • Transducer that convert physical variable to electric signal 
 • Sample and hold circuit 
 • Analog to Digital converter (ADC)
 • Interfacing circuit to enable Computer to read the data
 • Computer and its peripheral 

Since the analog data must be sampled, the sampling period must be short enough to overcome the aliasing problems. At least sampling rate must be twice the highest signal frequency. It must be noted that due to the limited number of bit of the ADC there must be rounding error when conversion take place, the greater the bit number the smaller the rounding error. For many industrial application 8 bit ADC is enough but for high accuracy 10 or more bit is required. A lot of benefit can be gained by using DAC. Before computer technology is available a manual system is applied for the system, a lot of man hour is needed when this is done manually.