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ABSTRACT
Data Acquisition system is an embedded system, which collects the data at predefined time intervals from different sensors for different physical measurements like temperature, light, Voltage variations, etc,. in fact, anything that you need to measure, you can capture it. In stand-alone application data Acquisition system, the output may be in the form of display, buzzer, memory storage devices etc.
This embedded project mainly consists of USB to Serial converter and analog to digital converter which provides an easy to use, isolated, high resolution data acquisition system compatible with USB.
The data Captured will be compared with the threshold values by the microcontroller. After comparing, decision will be taken by the microcontroller whether to trip off the system or not ie. if the detained value exceeds the predefined value the whole system will be tripped-off, in other case the data will be continuously displayed in the LCD.
The micro-controller will be interfaced with PC using USB-Serial converter through which we are transmitting the collected data to centrally located PC servers; for further analysis .These can also be called as Data Loggers. USB data acquisition devices are ideal for a variety of applications from simple data logging to embedded OEM systems.
CHAPTER 1
INTRODUCTION
The purpose of data acquisition is to measure an electrical or physical phenomenon such as voltage, current, temperature, pressure, or sound. PC-based data acquisition uses a combination of modular hardware, application software, and a computer to take measurements. While each data acquisition system is defined by its application requirements, every system shares a common goal of acquiring, analyzing, and presenting information. Data acquisition systems incorporate signals, sensors, actuators, signal conditioning, data acquisition devices, and application software.
Data acquisition hardware is either internal and installed directly into an expansion slot inside your computer, or external and connected to your computer through an external cable, which is typically a USB cable.
At the simplest level, data acquisition hardware is characterized by the subsystems it possesses. A subsystem is a component of your data acquisition hardware that performs a specialized task. Common subsystems include
• Analog input
• Analog output
• Digital input/output
• Counter/timer
Regardless of the hardware you are using, you must send information to the hardware and receive information from the hardware. You send configuration information to the hardware such as the sampling rate, and receive information from the hardware such as data, status messages, and error messages. You might also need to supply the hardware with information so that you can integrate it with other hardware and with computer resources. This information exchange is accomplished with software.
There are two kinds of software:
 Driver software
 Application software
For example, suppose you are using Data Acquisition Toolbox software with a National Instruments AT-MIO-16E-1 board and its associated NI-DAQ driver. The relationship between you, the driver software, the application software, and the hardware