SCADA stands for Supervisory Control and Data Acquisition; it is a type of industrial control system that can be used remotely. It operates using coded signals over communication channels and can be combined with data acquisition systems to acquire information regarding the status of remote equipment. This information can then be easily displayed, or recorded if needed.
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Main SCADA Components
To work effectively, a SCADA Industrial Control System needs a range of subsystems. The specific systems used may differ depending on the sector and specific machinery being monitored and controlled. However, in general, you can expect the following subsystems:
Remote terminal units - connect to the sensors in the process and convert their signals into digital data for remote monitoring.
Programmable logic controls - can be used in place of remote terminal units to achieve the same results. One of the reasons they are chosen is because they are more economical and provide greater flexibility.
Telemetry system - used to connect the remote terminal unit or programmable logic controller with the control center, data warehouse or enterprise.
Data acquisition server - a software service that connects the software services, via the telemetry, to the field device. It achieves this using industrial protocols.
Human-machine interface - allows a human operator to see the processed data, as well as monitor and interact with the process. Using the interface, a human operator can also create reports, set alarms and send notifications where needed.
Historian - another software service that is integral to the proper functioning of the system. It accumulates time-stamped data, as well as Boolean events that can be used by the human operator. The historian acts as a client that requests data from the data acquisition server.
Supervisory computer system - the key to the gathering of data and the sending of control commands to the SCADA system.
Communication infrastructure – allows all the different elements to communicate effectively.
Analytical instrumentation – while a common component of a SCADA system, it is usually specific to the system being monitored and controlled.
Concerns and the Way Forward
While a human operator remains at the heart of the system, they are only part of the equation. Much relies upon the reliability and security of the communications infrastructure. In case of malfunctions in the communications infrastructure, the system will not work effectively, if at all, while an insecure infrastructure could lead to outside influences gaining access to the entire system with far-reaching results.