DAS
Data Acquisition system
Basic principle
BY: MUYEMBA CHIMBOOLA
What is a Data Acquisition System?
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Is the process of digitizing data from the world
around us so it can be displayed, analyzed, and
stored in a computer.
• It a process of sampling signals that measure real
world physical conditions & converting it into
numeric values that can be manipulated by a
computer.
Data Acquisition System Block Diagram
Components Data Acquisition System
Components Data Acquisition System?
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Transducer − It converts physical quantities into electrical
signals.
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Signal conditioner − It performs the functions like
amplification and selection of desired portion of the signal.
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Analog to Digital Converter − It converts the analog input
into its equivalent digital output.
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Display device − It displays the data in digital format.
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Digital Recorder − It is used to record the data in digital
format.
Data Acquisition System
Measurements
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Current
Voltage
Strain
Frequency or time interval
Pressure
Temperature
Distance
Vibration
Angles
Digital signals
Weight
Data Acquisition System
Equipment
Data Acquisition System
Data Loggers
• Depending on the type of application, the data can be used to read
voltages, temperature measurements, humidity levels, currents, or other
signals of interest. Data loggers are self-contained data acquisition
systems with built-in processors and predefined software embedded in
the unit.
Conductivity meter
Data Acquisition System
• Data acquisition devices contain signal conditioning circuitry, as well as an
analog-to-digital converter. However, they need to be connected to a
computer in order to function.
• They are mostly plug and play devices
Proximeter
Data Acquisition System
Signal Capturing
Voltage Signals
The voltage signal is the most commonly used signal employed by DAQ
systems. Strain gauge bridge circuits, thermocouples, and gas concentration
probes, for example, all produce a voltage signal. Data acquisition hardware
conditions the signal and then converts it into a digital number by employing
an analog-to-digital converter. This digital value is stored by the computer
Data Acquisition System
Signal Capturing
Current Signals
Current is usually used for transmitting
signals in noisy environments since it is
much less affected by environmental
background noise. A data acquisition
system measures the amount of current
that flows and then stores the value in a
computer for analysis.
Data Acquisition System
Signal Capturing
Resistance
Resistance measurements are performed employing a current source
together with a normal voltage input. The current flows through an
unknown resistance and the voltage drop across that resistance is
measured. This voltage drop is then recorded by the data acquisition
system.
Data Acquisition System
Signal Capturing
Digital Signals
Digital outputs produced by switches
and are treated as logic signals. These
signals are sensed as on(1) or off(0).
When the digital signals are rapidly
changing and become pulse trains,
counter-timer type inputs must be
considered.
Data Acquisition System
Objective
• Monitor the complete plant operation to maintain online, safe
operation and control.
• It must be able to collect, summarize and store date for
diagnosis of the operation, status of equipment, and also for
records purposes
• It must be able to compute unit performance indices using online, real time data.
• It must be reliable, easy to operate and must be user friendly
Data Acquisition System
Conclusion
Data acquisition systems are a process for capturing, storing, analyzing, and
manipulating data. The data is acquired through different techniques
including voltage signals, current signals, power signals, etc. There are
different types of data acquisition systems utilized.
Some of them are multipurpose devices with an all-in-one configuration
whereas some are single-purpose devices designed for measuring data from
single parameters.
These systems offer so many benefits.
They are cost-effective, fast, versatile, and reliable. Data acquisition systems
are a very efficient and convenient way of recording data for further analysis.
Data acquisition systems not only improve data security since the process of
capturing data is now automated, they improve access to data for the users
while reducing errors.