What is scada? Definition and Details paessler com/it-explained/scada it explained: scada back to index Content

Core SCADA features
Supervisory control
SCADA systems are designed to oversee and monitor specific processes and behavior at
a supervisory level. The main role of a supervisory system is to link human operators to
digital data acquired from field devices. SCADA systems are event driven and are not
designed to take the initiative in performing advanced process control functions. They
respond to real-time events like an alert that a piece of equipment is overheating by
remotely switching it off, either automatically or manually.
A supervisory system may consist of a single computer in small SCADA systems or of
numerous computers running distributed software applications and linked to multiple
disaster recovery sites in a large SCADA network.
Supervisory control in SCADA systems is implemented through a supervisory controller
that links input and output elements and integrates with HMIs that are located in central
hubs and operated by people. While the supervisory control center does most of the
acquisition, processing, and transmission of data, this information is always directed to
the central control hub for analysis, reporting, and performance monitoring by people.
Industrial control systems (ICS)
SCADA systems fall under the umbrella term ICS. Some examples of ICSs are
programmable automation controllers (PAC), HMIs, PLCs, distributed control systems
(DCS), IEDs, and RTUs.
ICSs are categorized by their functionality, application, and complexity. For example,
RTUs connect different kinds of hardware to other control systems, like SCADA systems
or DCSs, while HMIs control human-to-machine (H2M) communications. PLCs are
designed to monitor and control field devices like sensors and actuators.
The main function of a SCADA ICS is to facilitate communication between disparate
remote hardware devices and human operators based on acquired data.

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SCADA telemetry
Telemetry involves the measurement and transmission of data and the state of remote
devices to a central location where it can be analyzed. SCADA systems use telemetry to
acquire, analyze, store, and report on the state of and measured data from field devices.
The term telemetry is sometimes used interchangeably with the term telematics but
telemetry is a subset of telematics.