SCADA Basics: An Overview of Automatic Control Systems

SCADA relates to software which is used to control hardware and acquire data from these devices. When we break it down to essentials, we have Supervisory control and data acquisition, which has been explained here.

SCADA (supervisory control and data acquisition) is a category of software application program for process control, the gathering of data in real time from remote locations in order to control equipment and conditions. SCADA is used in power plants as well as in oil and gas refining, telecommunications, transportation, and water and waste control.

scada overview

Such systems are used in monitoring and control of a manufacturing plant’s operating systems from a centralized location. It includes a mode for communication of information between the central host computer to the many scattered units (Programmable Logic Controllers). The systems may vary from a simple temperature reporting system in a building to complex monitoring systems for traffic lights. The major elements of the system are:

Master Station

It is a repository of real-time or near real-time reported data collected from the remote terminal units connected to the master system. Generally, it is a standard computer hardware equipment but there are few specialised available as well. The back end SCADA software must be able to repeatedly poll the RTUs for data values, should have software for their retrieval, storage and processing. The processing may include unit conversion, cataloguing into tables etc.

Human-Machine Interface

This is basically the command center that allows control of the devices. The values stored in the computers are accesses here in an understandable and comprehensible form by HMIs. These are helpful in providing diagnostics and management information with detailed schematics Humans work well with pictures, hence similar are the SCADA HMIs.

Remote Terminal Units (RTUs)

It connect to sensors in the process, converting sensor signals to digital data and sending digital data to the supervisory system.

Programmable Logic Controller (PLCs)

It is used as field devices because they are more economical, versatile, flexible, and configurable than special-purpose RTUs.

Communication infrastructure in SCADA

It provides connectivity to the supervisory system to the Remote Terminal Units.


How Industrial Automation Transforms Industries?


Today there is a high pressure on businesses to provide high quality and consistently better products at a competitive price. To address this challenge, businesses are approaching to industrial automation companies to design and develop products through robotic process automation.

Industrial automation helps improve the product quality and reduce design cost by adopting new, innovative and integrated technologies and services.

Industrial automation is made replacement to humans with computers and machines. The word Automation means a mechanism move by itself. Automation focuses on to automate operations and drive industrial processes without human involvement and achieve superior outcomes than manual operations.

Types of Industrial Automation:

Hard or fixed automation

This type of automation is deployed to perform fixed and repetitive operations in order to get high production rates. It leverages special purpose or dedicated equipment to automate the fixed sequence assembling or processing operations. Once it starts to work, it is difficult to change or modify the product design. So it is not flexible in providing varieties in products, but it improves the efficiency with greater production rate and decreases unit cost.

Soft or Flexible Automation

This automation system provides the automatic control equipment, which adds a flexibility for making changes in the product design. These changes can be made quickly through the commands given by the operators.

By using soft or flexible automation, manufactures can manufacture multiple products with different ranges of collective combination of processes rather than a separate process.

Programmable Automation

In this automation, assembling or processing operations are changed with the adjustment of control program in the automated equipment.

This automation is best fit for batch production process where product volume flows from medium to high. But in this automation, it is difficult to change and reconfigure the system for a new product or sequence of operations. So new product or the process to reconfigure a sequence of operations needs a lengthy setup.

Advantages of Industrial Automation

Increased productivity and efficiency

Human labours have some limitations and they may do errors, but machines have less chance to commit mistakes. For instance, computers don’t get tired from continuous working. On the other hand, machines can’t match human creativity. But they can do repetitive works, delivering better accuracy within less time.

Automation is used in areas where a high degree of accuracy is required. Machines can also be used in dangerous environments.

Improves product quality

Since the automation is used to reduce the human involvement, the possibility to reduce human errors is possible. In fact, industrial automation helps achieve uniformity and product quality and also it helps monitor all the industrial processes, from the inception of product to the completion of an end product.

Improves opportunities for customization

Today customers demand customized products to meet the needs of their particular markets. Therefore, manufacturers should be able to meet customer demands without compromising in quality.

Some companies focus on to increase flexibility in production by implementing automation through the use of sensors and configurable robots. They are able to produce products as for individual customer needs.

Increases the level of safety

Industrial automation increases the level of safety to workers by replacing them with automated machines in dangerous working conditions. Today, industrial robots and robotic devices are largely being used in such areas.

Before industrial automation companies were focused on to improve productivity and cut down costs, but today the focus is towards improving quality and bringing agility to the process.

PLC Program to Maintain the Pressure Head in a Bottle Filling System

This is a PLC Program to Maintain the Pressure Head in a Bottle Filling System.


Bottle filling has a constant speed of filling 20 bottles per minute. This speed depends on level of the tank due to its head pressure. To maintain this speed, pressure head of the filling tank has to be maintained at a particular. Implement this automation in PLC using Ladder Diagram programming language.

Diagram: (2)


  • Solid state level switches cannot be used here since level has to be continuously monitored.
  • Pressure is proportional to level. As level of a tank increases, pressure also increases.
  • Level gauges are highly sensitive to very small variations. Many companies such as Rockwell Automation and Endress+Hauser manufacture pressure gauges to measure liquid level of a tank.
  • Output of this gauge is terms of pressure so we have to convert pressure into equivalent current output. But let us assume here that maximum pressure that means when tank is full, it gives 20mA output and when tank is empty, it gives 4mA output which is in standard form 4-20mA.
  • Use conversion instructions to convert this 4-20mA data into registers. To do this, Analog modules for PLCs are used.
  • These modules convert 4-20mA into equivalent digital level signals.
  • Output of this Analog modules are stored in Hex form which are then processed by the processor and hex output is generated again.
  • Just like Analog input modules, Analog output modules are used convert digital output data into equivalent current signals to operate power supply circuit which varies output accordingly, to drive the final control element, here control valve.

PLC Program:

Here is PLC program to Maintain the Pressure Head in a Bottle Filling System, along with program explanation and run time test cases.

List of Inputs and Outputs

I:1/14 = Start                                                                                          (Input)
I:1/15 = Stop                                                                                            (Input)
B3:0/0 = Master Coil Bit                                                                          (Bit)
DIV = To divide total height of the tank                                        (Compute)
MUL = To multiply with the tank level to be maintained         (Compute)
N7:0 = Input from Level Gauge                                                        (Register)
N7:1 = Result (Variation per cm)                                                      (Register)
N7:2 = Result of multiplication                                                         (Register)
O:6 = I-P Converter                                                                                (Output)

Ladder Diagram to solve control pressure head:


Program Description:

  • RUNG000 is a latching rung to operate the system through Master Start and Stop PB.
  • RUNG001 comprises all the conversion needed to control level of the tank.
  • Output of transmitter is in current signals which is 4-20mA.
  • When output is 4mA, Analog Input Module converts it into 16bit equivalent hex numbers. Hence when input to Analog module is 4mA, it stores 0000h into register and when 20mA, it stores FFFFh into register. Here register N7:0. This conversion is done internally by the A-to-D converter in Analog Input Module.
  • Height of the tank is 10m or 1000cm. By converting it into equivalent hex, change in value per centimeter is 66 approximately which is stored in register N7:1.
  • Value of N7:1 is then multiplied with the preset value of tank level that is 900cm here.
  • This multiplication is stored into N7:2 register. Digital to Analog conversion of value stored in N7:2 is performed inside the processor and equivalent mA current is received from terminal O:6.
  • Current to Pneumatic converter then converts current signals into equivalent 3-15psi pneumatic signal and adjusts valve opening.

Runtime Test Cases:

Input                                           Output                                        Valve percentage open
N7:0 = 0000h                          O:6 = 0000h                                       Valve 100% Open
N7:0 = FFFFh                         O:6 = E506h                                         Valve 90% Open


SMPS (Switched Mode Power Supply)


D.C. to D.C. converters and D.C. to A.C. Converters belong to the category of Switched Mode Power Supplies (SMPS). The various types of voltage regulators, used in Linear Power Supplies (LPS), fall in the category of dissipative regulator, as they have  a voltage control element usually transistor or zener diode which dissipates power equal to the voltage difference between an unregulated input voltage and a fixed supply voltage multiplied by the current flowing through it. The switching regulator acts as a continuously variable power converter and hence its efficiency is negligibly affected by the voltage difference. Hence the switching regulator is also known as ‘non-dissipative regulator’. In a SMPS, the active device that provides regulation is always operated in cut-off or in saturation mode.
The input D.C. Supply is chopped at a higher frequency around 15 to 50 kHz using an active device like the BJT, power MOSFET or SCR and the converter transformer. Here the size of the ferrite core reduces inversely with the frequency. The lower limit is around 5 kHz for silent operation and an upper limit of 50 kHz to limit the losses in the choke and in active switching elements. The transformed wave form is rectified and filtered. A sample of the output voltage is used as the feedback signal for the drive circuit for the switching transistor to achieve regulation.
The oscillator in above figure allows the control element to be switched ON and OFF. The control element usually consists of a transistor switch, an inductor, and a diode. For each switch ON, energy is pumped into the magnetic field associated with the inductor which is a transformer winding in practice. This energy is then released to the load at the desired voltage level.
By varying the duty cycle or frequency of switching, we can vary the stored energy in each cycle and thus control the output voltage. Higher efficiency is obtained since only the energy required is pumped to maintain the load current hence no power dissipation.
The major feature of SMPS is the elimination of physically massive power transformers and other power line magnetic. The net result is smaller, lighter package and reduced manufacturing cost, reducing primarily from the elimination of the 50 Hz components. The basic concept of switching regulator in a simple form is shown in this figure below.
  • D.C. to D.C. Converter:
  • Forward Converter:
  • Flyback Converter:
  • Self-Oscillating Flyback Converter: 
The block diagram of D.C. to D.C. converter (SMPS) is shown here.
Here, the primary power received from AC main is rectified and filtered as high voltage DC. It is then switched at a huge rate of speed approximately 15 kHz to 50 kHz and fed to the primary side of the step-down transformer. The step-down transformer is only a fraction of the size of a comparable 50 Hz unit thus reliving the size and weight problems. The output at the secondary side of the transformer is rectified and filtered. Then it is sent to the output of the power supply. A sample of this output is sent back to the switch to control the output voltage.
SMPS rely on PWM to control the average value of the output voltage. The average value of the repetitive pulse waveform depends on the area under the waveform. As load increases, output voltage tends to fall. Most switching power supplies regulate their output using the method called Pulse – Width Modulation (PWM). The power switch which feeds the primary of the step-down transformer is driven by the PWM oscillator. When the duty cycle is at 50%, then the maximum amount of energy will be passed through the step-down transformer. As the duty cycle decreases the power transmitted is less hence low power dissipation.
The Pulse Width signal given to the switch is inversely proportional to the output voltage. The width or the ON time of the oscillator is controlled by the voltage feedback from the secondary of the rectifier output and forms a closed loop regulator. Since switching regulator is complex, modern IC packages like Motorola MC 3420/3520 or Silicon General SG 1524 can be used instead of discrete components.

How to read a piping & instrumentation drawing?


A piping and instrumentation diagram (P&ID) is a detailed diagram in the process industry which shows the piping and vessels in the process flow, together with the instrumentation and control devices. They usually contain the following information:

Process piping, sizes and identification, including:

  • Pipe classes or piping line numbers
  • Flow directions
  • Interconnections references
  • Permanent start-up, flush and bypass lines

Mechanical equipment and process control instrumentation and designation (names, numbers, unique tag identifiers), including:

  • Valves and their identifications (e.g. isolation, shutoff, relief and safety valves)
  • Control inputs and outputs (sensors and final elements, interlocks)
  • Miscellaneous – vents, drains, flanges, special fittings, sampling lines, reducers and increasers
  • Interfaces for class changes
  • Computer control system
  • Identification of components and subsystems delivered by others

P&IDs are originally drawn up at the design stage from a combination of process flow sheet data, the mechanical process equipment design, and the instrumentation engineering design. During the design stage, the diagram also provides the basis for the development of system control schemes, allowing for further safety and operational investigations, such as a Hazard and operability study (HAZOP). To do this, it is critical to demonstrate the physical sequence of equipment and systems, as well as how these systems connect.

Kindly find in the image below P&ID symbols used in P&ID drawings for different valves and pipings used in process flow  and P&ID diagrams.


P&IDs also play a significant role in the maintenance and modification of the process after initial build. Modifications are red-penned onto the diagrams and are vital records of the current plant design.They are also vital in enabling development of;

  • Control and shutdown schemes
  • Safety and regulatory requirements
  • Start-up sequences
  • Operational understanding.

P&IDs form the basis for the live mimic diagrams displayed on graphical user interfaces of large industrial control systems such as SCADA and distributed control systems.

Automation Training benefited for the career of Fresher Engineering students

Innovic India Pvt. Ltd.

There is no harm in saying that automation industry is growing rapidly with the increasing need and demand in the global market values. The wonders and appreciation that this industry has got is really immense and valuable change for the better profitability of the industries. It is an obvious statement that with rise of automation industry, the training of such sector is also growing in its demand. To serve the same, automation training institute in Noida, Delhi NCR are providing the immense opportunities for the students to avail the benefit of working under Industry experts.

Students who are not quite sure whether training institute can avail them a better career or not, the answer to such students can be given by those non-trained students still struggling to pursue the job opportunity.

Why Delhi NCR, If you ask? The fact is not hidden that Delhi NCR is a shelter to the entire profitable and widely known industrial specialist who are sustaining the immense reputation in the market till now. For students, automation training institute in Noida, Delhi NCR.   brings an immense opportunity to uplift that knowledge and learning most with the practical understanding of the system youth in automation industry.

Moreover, it is an opportunity for the students to examine their skills and struggle to prove the tremendous passion they avail for automation industry. There is no doubt that path leading to great success is full of challenges and struggle that a student needs to bear for the success stories to be told and written in the future.

Automation training institute in Noida, Delhi NCR will bring a bench mark change in students’ life to switch from the academic struggle to the real life opportunities that will help them to write history of their coming future.

As we know there are no shortcuts to success the struggle and learning experience through Advance Automation training Institute in Noida, Delhi NCR will bring forth the vast and long journey to be initiated from this point. The time to sit back and relax will be realized in your dreams while you will be working and learning the essential sectors and systems of automation industry.


Data Acquisition System (DAQ or DAS)

What is Data Acquisition?

The Data Acquisition is the process of sampling signal that measures real-world physical conditions and converting the resulting samples into digital numeric value that can be manipulated by a computer.

The microprocessor-based personal computers are extensively used to implement direct digital control. For such PCs, special Printed Circuit boards are used called as Data Acquisition systems in process control. These system work are developed for providing input and output analog data, these are used when the PC is used in control system. Just like other peripheral devices such as scanner, printer, game board etc..

Components of a DAQ system:

Untitled designSensors:

Sensors convert the physical quantity such as temperature, pressure, flow etc, into a readable voltage or current signal for easy signal processing.

The sensor sends the measured valve directly to the signal conditioning device or to data acquisition board.

Signal conditioning:

The sensor output may contain noise signal as well may not in the range to be detected by the computer system. A signal conditioning unit filters the signal and thus improve the quality of the signal pass through the DAQ.

The common signal conditioning includes the amplification, linearization, filtering, attenuation, common mode rejection etc.

Analog to Digital converter:

An A/D converter converts the analog signal to digital readable signal to the computer system. The conversion is necessary to enable the computer to process or store the signal.


  • Reduced data reduntancy
  • Improved data security
  • Improved data access to user through use of host and query language
  • Reduced updating error and increased consistency
  • Reduced data entry and storage


  • Database system is complex, difficult and time-consuming
  • Damage to database affect all application program
  • Hardware and Software start-up cost
  • Initial training required for all programmers and users

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