industrial//industrial automation//SCADA

**Supervisory Control And Data Acquisition** does two things: supervision and data acquisition. It receives information from PLCs, RTUs and other equipment and lets people see states, show alarms, keep histories, send setpoints, plot trends and operate processes remotely.

Supervisory Control And Data Acquisition does two things: supervision and data acquisition. It receives information from PLCs, RTUs and other equipment and lets people see states, show alarms, keep histories, send setpoints, plot trends and operate processes remotely.

Its native question is "what is the state of the plant now?": motor on or off, level 73 %, alarm active, valve open. That present-tense focus is also its limit: SCADA data are not automatically contextualized for finance, logistics, maintenance, analytics or benchmarking, which is how a plant ends up with data silos (data contextualization).

It serves both factories and geographically distributed infrastructure: electricity, water, gas and oil pipelines. In the distributed case the field side is an RTU and the center is a master station, joined by radio, cellular, fiber or satellite.

A SCADA should not execute the fast, critical control. That stays in the PLC or DCS; SCADA supervises. The operator's screen is the HMI, which can be part of a SCADA or a local panel on a machine.

Historically each PLC vendor exposed data its own way, so a SCADA would have needed a driver per protocol. The OPC layer was created to give it one interface instead (OPC).