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SCADA system

Last Updated on 2021-12-01 Hits:2560

Supervisory Control and Data Acquisition SCADA is a process control system architecture that uses computers, network data communication and graphical human-machine interface (HMI) to realize advanced process supervision and management and control.

The SCADA system communicates with other devices, such as programmable logic controllers (PLC) and PID controllers, to interact with factories and equipment involved in the industrial process.

The SCADA system occupies a large part of the control system engineering. The SCADA system collects information and data from the real-time analysis process, records the data, and displays the collected data on various HMIs. That is to say, process control operators can monitor what is happening on-site through remote means, and operators can control these processes by interacting with HMI.

For example, the application of SCADA system in the oil and gas field. Petroleum or chemicals are transported using large pipelines. Safety plays a vital role in this process. Therefore, there should not be any leakage along the pipeline. In case of leakage, the SCADA system is used to identify the leakage. It infers information, transmits it to the system, displays the information on the computer screen, and alerts the operator.

SCADA systems are essential to many industries and are widely used for process control and monitoring. The SCADA system is widely used because it has the ability to control/monitor/transmit data in an intelligent and seamless manner. The digital age is a data-driven world. In the digital road, we need to find ways to improve the degree of automation and make smarter methods through the appropriate use of data, and the SCADA system is the way to achieve this goal.

Many people think that SCADA is a piece of software when talking about SCADA systems. In fact, general-purpose SCADA systems consist of hardware and software. The SCADA software part is installed on the computer side for calculation, and the hardware component is used to receive input data and pass it to the system for further analysis. SCADA systems are used in various industries and manufacturing sectors, such as energy, food and beverage, oil and gas, power, water and waste management sectors, etc.

SCADA history

Before the SCADA system was born, many manufacturing workshops, factories and remote sites required personnel to manually control and monitor equipment through buttons and analog dial switches.

As the scale of industrial and manufacturing units expanded, they began to use relays and timers, which provided supervisory control to a certain extent without having to send people to remote locations to interact with each device. But relays and timers can only solve problems with minimal automation, and it is difficult to reconfigure the system and find faults. Therefore, all industries need a more efficient and fully automated monitoring and control system.

In the early 1950s, computers were developed for industrial control purposes. At that time, monitoring began to become popular in major utilities, oil and gas pipelines, and other industrial markets.

In the 1960s, telemetry technology for monitoring was established, which allowed automatic communication to transmit measured values and other data from remote sites to monitoring equipment.

Around 1970, the term SCADA came into being with the development of the concept of microprocessors and PLCs.

In the early 2000s, a distributed SCADA system was developed.

The emergence of the modern SCADA system enables us to control and monitor real-time data anywhere in the world, which has brought the industry to a higher level. Even if the operator does not have much software development knowledge, he can still manage modern SCADA systems. Moreover, most modern SCADA designer applications have rapid application development (RAD) capabilities, even if users do not have extensive software development knowledge, they can make it relatively easy for users to design applications.

The introduction of modern IT standards and practices (such as SQL and Web-based applications) into SCADA software has greatly improved the efficiency, safety, productivity and reliability of the SCADA system. Compared with the outdated SCADA software, the SCADA software that utilizes the SQL database function has a huge advantage. One of the big advantages of using SQL databases with SCADA systems is that it can be more easily integrated into existing MES and ERP systems, allowing data to flow seamlessly throughout the organization. Historical data from the SCADA system can also be recorded in the SQL database, so that data analysis can be performed more easily through data trend analysis.

SCADA basics

Goals to be achieved by SCADA:

Monitoring: SCADA system continuously monitors physical parameters

Measurement: Measure parameters used for processing

Data collection: Get data from remote terminals, data loggers, etc.

Data communication: communication and transmission of data

Control: online real-time monitoring and control process

Automation: automatic transmission, automatic function

The composition of the SCADA system:

Main terminal unit MTU: MTU is the core of the SCADA system. It includes a computer and a server, which realizes the communication between MTU and RTU, collects and saves data, realizes the interface between the system and the operator and realizes the communication with other external systems.

Remote terminal unit RTU: RTU is usually connected with sensors and actuators to collect information from these sensors and then send the data to MTU. Usually we use PLC as RTU in SCADA solutions, which helps to directly transmit and control data.

Communication network: The connection between the on-site RTU and the central MTU. Network topology definition is also very important when implementing SCADA system

Functions of SCADA system

A SCADA system is a collection of hardware and software components that interact to enable manufacturing units to perform specific functions.

Monitor and collect data in real time

Realize the interaction between field equipment and control station through human machine interface (HMI)

Log system events

Virtually control the manufacturing process

Information storage and reporting

How to choose a SCADA system

SCADA software plays an important role in the analysis and control of the entire process. There are several large companies around the world that specialize in SCADA systems. Before we choose and implement a SCADA system, we need to consider many factors. for example

Software life/life: A lot of money will be invested when purchasing SCADA, so it is best to check whether the software can be used continuously for 5 to 10 years

Information request: To obtain detailed information about suppliers and sellers, the supplier's specific field of expertise, geographic location, and industry dynamics play a major role in product selection. If you buy software from a particular supplier, you need to consider whether this supplier has the ability to provide technical support.

Historian: The software needs to be able to save time-stamped data for future reference. The software needs to be able to process and record field data proficiently.

SCADA technology: Technology is constantly evolving, and we do not always need to use the latest technology on the market when choosing a certain software or system solution. Instead, choose a technology that can remain stable and safe for a long time.

Alarm monitoring and management: The alarm function required by the SCADA system. There are two types of alarm systems, namely system-defined alarms (managed by the system itself) and user-defined alarms (managed by the user).

SCADA provided by some large companies in the market:

Citect SCADA-Schneider A compact, flexible and reliable SCADA software developed by Schneider Electric. The latest product they released is Citect SCADA 2018. Citect SCADA is still one of the commonly used SCADA technologies. If you are a SCADA developer, it is necessary to learn about the platform.

InTouch-Wonderware InTouch has become one of the largest SCADA suppliers on the market. It comes from Wonderware, which is now owned by Schneider Electric. Wonderware has become popular in the market very quickly. The Wonderware system platform is a SCADA system with many modular and very versatile "plug and play" components. This modular solution allows us to easily customize it as needed. The advantage of InTouch is that they use open communication standards and can run on most PLC systems.

Experion SCADA-Honeywell Honeywell (Honeywell) is commonly used in PLC systems and is also an important participant in the SCADA market, providing a software platform for the programming of SCADA and HMI software systems. Users can use their software for stand-alone SCADA solutions, or use it with Honeywell's PLC platform.

IFIX-General Electric GE is one of the world's largest manufacturing companies and an important participant in the SCADA market. IFIX is one of their software solutions, it is a very flexible SCADA system. The advantage of using iFIX is that you can use HTML5 to quickly develop screens. Another reason is that it has many drivers for you to set up network and distributed systems and realize the connection and exchange of information with most modern PLCs. GE also has its own brand of PLC-but the GE SCADA system does not require these GE PLCs to operate.

Ignition – Inductive Automation Ignition is a SCADA solution that utilizes the latest IoT architecture to realize its full potential. If you want an up-to-date system that uses all Industry 4.0 specifications and technologies, then Ignition is a very good choice. Compared with some advanced SCADA systems, Ignition is relatively new, but due to Ignition's IoT integration and its advantages that it can be used with most PLC systems, Ignition has been chosen by many companies as its SCADA solution.

SIMATIC WinCC V7-Siemens The Siemens SCADA system has existed for many years and is called "WinCC". Siemens is one of the largest players in the PLC and SCADA industry. Siemens has been developing its PLC and SCADA platforms to incorporate modern technology for many years. Because Xijia has rich experience in the SCADA industry, many companies trust and use their SCADA systems.

KingView-Asia Control Technology has a very large domestic market share, and it can be said to be a national industrial software brand. Kingview has extensive support for device drivers, with good stability and cost-effectiveness. Because of the wide range of applications in the domestic industry, the value of products has been continuously improved for many years.

SCADA system application

SCADA makes full use of functions such as flexibility, reliability and scalability in automated complex systems. With countless applications in the real world, SCADA can effectively provide monitoring and control alternatives in a wide range of fields from energy production to agricultural systems. SCADA is widely used in different fields such as chemistry, natural gas, water, communication and power systems.

Power generation, transmission and distribution use SCADA system to detect current and line voltage, monitor the operation of circuit breakers, and monitor the online or offline status of the grid.

Manufacturing unit SCADA system is used to regulate industrial automation and robots, and to monitor process and quality control

Transportation and Railway Use SCADA to regulate the electricity of subways, trams and trolleybuses. Automated railway traffic signal. Monitor and identify trains and buses, and control railway crossings

Water, wastewater and sewage treatment The water department uses SCADA to monitor and control water flow, water tank, pipeline pressure and other data

Buildings, Facilities and Environment Facilities managers use SCADA to regulate HVAC, cooling, lighting and input systems


Thermal power plants Most of the operational inspections of thermal power plants are automatic, but sometimes manual operations may be required. Therefore, it is necessary to be equipped with a monitoring and alarm system. When certain working parameter counters greatly deviate from their normal range, an alarm will be issued to the plant operator. In thermal power plants, the requirements for reliability and effectiveness are very high. In order to improve reliability, automation is required to improve the efficiency of general power plants. Automation is established through the use of PLC and SCADA, thereby reducing worker errors. The SCADA system is used to supervise the entire process

Forestry, pulp and paper industry Forestry, pulp and paper industries also rely on SCADA systems. From the perspective of automation and process control, energy management, drive control, power protection, cabinet systems and security, SCADA has many uses in the industry. The SCADA system is used throughout the paper supply chain-including various processes such as chipping, evaporation, refining, cleaning, drying and pressing. By using the established SCADA system, this complex process from beginning to end from tree to paper is automated.

The relationship between PLC and SCADA

When you are new to control engineering, you may confuse PLC and SCADA. Although they are related, they are obviously different from each other.

PLC-Programmable Logic Controller PLC Programmable Logic Controller In essence, this is a sturdy and durable microcomputer, placed in the field and in a panel, with a large number of inputs and outputs imported from field devices to the PLC. The PLC will monitor the state of these inputs (such as the speed of the motor), make judgments based on the internal program logic, and output various signals to control these field devices (such as stopping the motor).

SCADA system (Supervisory Control and Data Acquisition) From the perspective of ISA95, SCADA is at the upper level of PLC. PLC is part of the SCADA network and forms an interface between the scene and SCADA. SCADA usually obtains data through communication with PLC, records and stores. The PLC continuously executes its programs, reads inputs and writes outputs. The PLC's own data storage capacity is limited, while the SCADA system is used to retain the historical status of these inputs and outputs for data analysis or auditing.


Although we can program the SCADA system to control the scene, we usually put the easy-to-program logic content into the PLC (program into the PLC), so that the PLC can run automatically and deal with any situation encountered. Of course, the actual situation may be very complicated. We need the operator's input to make the system run normally. At this time, the operator can realize the control through the SCADA screen (ie HMI). In general, the SCADA system is mainly used for monitoring and data acquisition, but it also has control functions for use in irregular or complex situations. SCADA allows operators (and control system engineers) to see an overview of the plant from a distance, allowing them to respond to any abnormal conditions.

It should be noted that the SCADA system technically includes PLC, and SCADA communicates with PLC. The PLC is located on site and will read all the inputs on site (for example, the conveyor belt has stopped) and write the outputs (for example, start the conveyor belt) according to its programming method. The PLC forms part of the SCADA network, and it receives and executes certain commands from the SCADA (for example, an operator command to stop the pump).

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