Supervisory Control and Data Acquisition is the abbreviation for SCADA. A SCADA system is a software-based program used in industrial manufacturing. This system helps to manage various hardware parts. 

As the acronym suggests, a SCADA system also includes a data component that would give the user a historical picture of a system.

These systems are helpful in manufacturing settings to combine controls across many production lines. They help to gather valuable data and inform business choices. Its overall results in process control and improvement.

SCADA, or supervisory control and data acquisition systems, is a pretty long terminology. In truth, SCADA is long-established, though not particularly worldly. It is the method for remotely monitoring utilities and other critical infrastructure and production applications.

SCADA system automates the data throughout the utility’s applications, which collect the data. SCADA systems are industrial control systems by definition (ICS). We can classify them as operations technology (OT). It includes the hardware, software, and communication tools used for information creation, storage, exchange, and use.

Four layers to understanding the SCADA system: SCADA for Report Utilities Monitoring

SCADA systems are created the same way regardless of what they monitor. 

There are four layers that group hardware, software, and connectivity. 

  1. Field instrumentation
  2. Programmable logic controllers (PLCs)
  3. Remote telemetry units (RTUs)
  4. Communications

Although manufacturing facilities, oil and gas refineries, power plants, water and wastewater treatment facilities, and remote utility monitoring are typical SCADA system applications. This blog will only cover water/wastewater, energy, and other utility monitoring.

  • Field instrumentation:

Hardware for field instrumentation is the first layer of a SCADA system. For instance, instrumentation systems at a water utility often include sensors, samplers, relays, and actuators. In this use, a temperature or pH sensor placed within a drinking water pipe tracks variations over time that may indicate water quality alterations.

Piezo vibration sensors can measure pump and generator physical stress. To close a valve, for instance, an actuator driven by an electric source can transform the electric energy into mechanical energy. Field instrumentation generates, consumes, or both creates and consumes data from the perspective of monitoring and automation.

  • PLCs and RTUs:

PLCs and RTUs are present in the second layer of SCADA systems

Note: remote telemetry and terminal units are used interchangeably to refer to the same class of devices. 

PLCs and RTUs collect real-time or continuous data by connecting to field instrumentation. They then carry out increasing degrees of control and communicate data to the SCADA host platform.

PLCs are, as their name implies, designed and engineered for industrial control and automation using programmable measurement processing. 

PLCs often handle analog and digital inputs and outputs (including sensors) (such as relays and actuators for the pump, valve, and hydraulic cylinder operational control). PLCs and the microprocessors that run their computing functions are tough, so they can endure challenging environmental factors, including dust, humidity, vibration, heat, and cold. PLCs also use more reliable operating systems appropriate for deterministic logic execution.

Those familiar with RTUs know they were formerly somewhat rudimentary telemetry instruments that transferred data from field equipment across fixed or wireless communication networks to the SCADA host platform. Early RTUs had more advanced communication capabilities but lacked PLCs’ processing and control capabilities. 

PLC and RTU technologies, which were formerly very different, have blurred over the last few decades. PLC and RTU manufacturers have reacted to changing client expectations for PLCs with excellent communications capabilities and RTUs with more processing and control capabilities.


PLCs and RTUs link field instrumentation to the SCADA host platform via the communications layer, the third SCADA system tier. SCADA uses many communication protocols to establish connectivity across wired or wireless (radio, satellite) networks. The typical communication medium for SCADA  has changed to fiber optic cable over the past few decades.

SCADA systems were first designed for inside-the-fence applications, such as factory floors, where onsite power supply is easily accessible. Field instrumentation and the SCADA host platform are located together or close by. However, they have changed. 

As the number of SCADA system integrators and developers has increased, vendors competing for large procurement contracts have looked for ways to stand out from the competition (resulting in market fragmentation). A wide range of communication protocols, for instance, serve as the glue that connects PLCs and RTUs with the SCADA host platform.

The industry is gradually switching from outdated proprietary protocols to non-proprietary ones. 

OPC creates a standardized collection of objects, interfaces, and methods that control how SCADA host platforms communicate with PLCs and RTUs. The OLE, COM, and DCOM (Distributed Component Object Model) technologies created for Microsoft Windows are the foundation of the classic OPC protocol.

Similar to OPC, the Distributed Network Protocol (DNP3) was created to provide open, standards-based interoperability across the components offered by different SCADA system vendors. DNP3, initially devised with the demands of power utilities in mind, makes it possible to have more reliable communications even in difficult situations where electromagnetic interference may bring distortion. The 

SCADA Host Platform:

SCADA host platforms include:

  • Software drivers.
  • A SCADA engine.
  • One or more databases.
  • A human-machine interface for the software and information technology layer (HMI).

The SCADA system architecture’s brain is the host platform.

How did SCADA host platforms work?

Data streams produced by field instrumentation flow via PLCs and RTUs over the communication layer. Communication drivers then integrate data with the engine. The engine stores and runs queries from a database architecture that displays field instrumentation and physical processes, visualizing data, trends, and alarms.

The HMI, the means through which SCADA engineers, operators, technicians, and other decision-makers manage the complete SCADA system design and control strategy, is the last component of the SCADA host platform.

The majority of value addition is driven by the SCADA host platform, which derives from its feedback mechanisms. The SCADA engine is a data fusion and analytics platform that combines data from the field. It sends instructions to PLCs, RTUs, and field instruments to automate and enhance equipment and infrastructure management.

Last words:

SCADA systems are the brain and heart of the industrial sector, especially in cases when assets are dispersed and located in remote areas. They control data collecting, perform data fusion and analytics, and automate industrial processes.

SCADA systems are the brain and heart of the industrial sector, especially in cases when assets are dispersed and located in remote areas. They control data collecting, perform data fusion and analytics, and automate industrial processes.

Prismecs guarantees the highest level of security planned for following regional governmental rules, regulations, and guidelines. For all SCADA system and SIS services, get in touch with Prismecs, schedule an appointment with us or ask for advice. The number to call is 18887747632.

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