Introduction to Data Acquisition (DAQ)


Introduction

The simplest way to store data is to record it on paper with either a strip-chart recorder or an x-y plotter. For greater utility data can be digitized and stored in computer files for later data analysis. Many instruments digitize and store data in memory for subsequent transfer to a computer file. The analytical signal can also be digitized and stored to a computer data file using a computer data acquisition (DAQ) board.

Data Transfer

Data that has been digitally stored in an instrument can be transferred to a computer by RS-232 serial or general-purpose interface bus (GPIB) protocols. The advantage of using the RS-232 port is that it is available on all computers, the disadvantage is that it is not a fast transfer since it is a serial transfer mode. The GPIB protocol uses 24 parallel data lines and provides fast data transfer, but requires purchase of a special plug-in interface board. Many instruments are now available with a DOS-compatible floppy disk drive. The disk drive makes file storage and transfer easy, but can be cumbersome for large numbers of files and for very large individual data files.

Computer DAQ

Voltages can be read into computer memory through plug-in DAQ boards that contain analog-to-digital converters. Many of the commercial DAQ boards also support digital and trigger inputs and analog and digital outputs for integrated instrument control and acquisition. A variety of software packages support the commercially available DAQ boards for data acquisition and instrument control.

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Copyright © 1996 by Brian M. Tissue, all rights reserved.

/chem-ed/electron/daqintro.htm, updated 5/29/96