Learn about Data Acquisition DAQ. Types of Data Loggers & It’s Working

DAQ Data Acquisition: This is a procedure of analyze voltage, current, temperature, pressure or sound with digital systems which collect data. Combining such a process in system that will be data acquisition systems. For making such a system we need some equipment: Sensors, Signal Conditioning, Analog input (A/D) board, Computer, Output Interface.

DAQ Systems also known as data logger and data recorders and working on same process as DAQ Systems. Data Loggers is a compact, battery-powered device equipped with internal microprocessors, data storage and more sensors.

Types of DAQ Systems:

• Mechanical data loggers
• Electronic data loggers
• Wireless data loggers

In other words, we also define some more DAQ Systems in terms of their physical properties:

v Analog Data Acquisition Systems

v Voltage Data Acquisition Systems

v Thermocouple Data Acquisition Systems

v Real-Time Data Acquisition Systems

v High Speed Data Acquisition Systems

v Temperature Data Acquisition Systems

Working of data loggers:

Data loggers are basically organised with lots of sensors devices for measuring physical properties. Sensors capture temperature, light, pressure, sound, acidity, humidity & heat. This sensor spreads signals to an interface which is directly connected to computers. In turns, this interface box functions as a converter of analogue signals into digital signals which understand by Computers.

Benefits of data logging

• High Speed & high accuracy rate during data gathering.
• Data logging is automated without human interaction
• Data loggers are also useful in security & Safety.
• Data loggers are useful in reading weather for long or short time.
• Data can be displayed through line, pie and bar graphs for analysis.
• Through this device we can display data in lines, pie and bar graphs for analysis.
• Data loggers help save time and costs.

The basic components required for the acquisition and conversion of analog signals into equivalent digital form are the following:

• Analog Multiplexer and Signal Conditioning
• Sample/Hold Amplifier
• Analog-to-Digital Converter
• Timing or Sequence Logic

Process:

Basic process of data acquisition hardware is very simple. An AC & DC converter that delivers a sequence of values presenting analogue signal to Software programmed. Actually in process, DAQ system is more complex but it creates easy interface between user and computer. All data loggers basically convert a signal derived from sensors into binary values like 1010101. The sensors are connected to an amplifier that coverts signal to potential. The amplifier is in turn connected to a digitizer, which contains AC-DC converter, the digitizer produce a sequence of values representing the signal.

The Personal Computer -

The computer used for your data acquisition system can drastically affect the maximum speeds at which you are able to continuously acquire data. Today’s technology boasts Pentium and PowerPC class processors coupled with the higher performance PCI bus architecture as well as the traditional ISA bus and USB. With the advent of PCMCIA,portable data acquisition is rapidly becoming a more flexible alternative to desktop PC based data acquisition systems. For remote data acquisition applications that use RS-232 or RS-485 serial communication, your data throughput will usually be limited by the serial communication rates.

Transducers -

Transducers sense physical phenomena and provide electrical signals that the DAQ system can measure. For example, thermocouples, RTDs, thermistors, and IC sensors convert temperature into an analog signal that an ADC can measure. Other examples include strain gauges, flow transducers, and pressure transducers, which measure force, rate of flow, and pressure, respectively. In each case, the electrical signals produced are proportional to the physical parameters they are monitoring.

Signal Conditioning -

The electrical signals generated by the transducers must be optimized for the input range of the DAQ board. Signal conditioning accessories can amplify low-level signals, and then isolate and filter them for more accurate measurements. In addition, some transducers require voltage or current excitation to generate a voltage output. Figure 2 depicts a typical DAQ system with SCXI signal conditioning from National Instruments.

Amplification – The most common type of conditioning is amplification. Low-level thermocouple signals, for example, should be amplified to increase the resolution and reduce noise. For the highest possible accuracy, the signal should be amplified so that the maximum voltage range of the conditioned signal equals the maximum input range of the analog-to-digital converter (ADC). For example, SCXI has several signal conditioning modules that amplify input signals. The gain is applied to the low-level signals within the SCXI chassis located close to the transducers, sending only high-level signals to the PC, minimizing the effects of noise on the readings.

Isolation - Another common application for signal conditioning is to isolate the transducer signals from the computer for safety purposes. The system being monitored may contain high-voltage transients that could damage the computer.

Author ---- This is from my knowledge page & I am Piyush Yadav, writing this technical description about basic introduction for DAQ acquisition and data loggers. Actually I am just making introduction for data acquisition system and explaining data logger function that helps to understand customers & users requirement. This article is helpful for civil engineering & research education students & professionals.

This is Piyush Yadav, Beginners in Content publication. Having superb opportunities to collect huge amount of curiosity regarding new inventions in instrumentation industry. See more : http://www.aimil.com