In this article, I am going to discuss the data acquisition system block diagram, function of each block, and its applications. This article will provide you an overview about data acquisition system in simple words.
Data acquisition system (DAS) is a computerized system that collects data from the real world, converts it into the form of electrical signals and do required processing on it for storage, and presentation on computers.
The complete system is controlled and operated by a software application. This software application is developed by using general-purpose high-level programming languages like C, C++, java, etc.
These systems are used in industrial and commercial fields. They are used for collecting, storing and processing of data.
The data acquisition system can be divided into two types:
- Analog data acquisition system
- Digital data acquisition system
The analog data acquisition system gives an analog output whereas the digital data acquisition system gives a digital output.
Analog DAS is used when wide frequency width is required or when lower accuracies can be tolerated.
Digital DAS is used when physical quantity being monitored has a narrow bandwidth (i.e. when the quantity varies slowly). Also, high accuracy and low per channel cost are required. These are more complex than analog DAS.
The digital data have more advantages over analog data. Some of those are:
- easy and fast processing,
- easy and fast transmission,
- easy display,
- less storage space is required,
- more accurate.
Due to these advantages, mostly the digital data acquisition system is preferred.
Data Acquisition System Block Diagram
A generalized data acquisition system block diagram is shown in Figure.
The function of each block is as under:
Transducers: They are converting physical quantities (such as temperature, pressure, etc.) into electrical quantities, or measuring electrical quantities directly. They collect data from the physical world.
The most commonly used transducers are:
- RTDs, thermocouples, and thermistors for temperature measurements.
- Photosensors for light measurements.
- Strain gages, piezoelectric transducers for force and pressure measurements.
- Microphone for sound measurements.
- Potentiometer, LVDT, optical encoder for position and displacement measurements.
Signal Conditioning Unit: The signal produced by the transducers may or may not be very suitable for our system to work properly. It may be very weak, very strong or may have some noise.
To convert this signal into the most suitable form, amplification, and filtration is done respectively by signal conditioning unit. So the signal conditioning unit converts electrical signals in the most suitable form.
Multiplexer: The multiplexer receives multiple analog inputs and provides a single output signal according to the requirements.
If a separate channel is used for each quantity, the cost of installation, maintenance, and periodic replacement becomes high. Therefore, a single channel is used which is shared by various quantities.
Analog to Digital (A/D) Converters: The data is converted into digital form by A/D converters.
After the conversion of data into digital form, it is displayed with the help of oscilloscopes, numerical displays, panel meters to monitor the complete system.
Also, the data can be either permanently or temporarily stored or recorded according to the requirement. The data is recorded on optical, ultraviolet, stylus or ink recorders for future use.
Objectives of Data Acquisition System
- It must collect the necessary data at the correct speed.
- It must use all the data efficiently to inform the operator about the state of the system.
- It must monitor the complete system operation to maintain on-line optimum and safe operations.
- It must be able to summarize and store data for the diagnosis of operation and record purpose.
- It must be flexible for future requirements.
- It must be reliable and not have a downtime of more than 0.1%.
- It must provide an effective communication system.
Applications of Data Acquisition System
The data acquisition system is used in industrial and scientific fields like aerospace, biomedical and telemetry industries.
Thanks for reading about digital data acquisition system block diagram explanation.
Instrumentation | All Posts
- Characteristics of Transducers
- Types of Errors in Transducers
- How to Select a Transducer
- Thermistor Working Principle
- Thermocouple Working Principle
- LVDT Theory | Advantages | Disadvantages
- Strain Gauge Working Principle
- Resistance Temperature Detector Working Principle
- Piezoelectric Transducer Working Principle
- Data Acquisition System Block Diagram
- Pressure Transducer Types