SCADA is a combination telemetry and data acquisition system. The system is composed of collecting information, transferring it back to a central control site or main station computer, conducting the necessary analysis and control, and then displaying the data on an operator screen. A SCADA system is primarily used to monitor and control a plant, pipeline or equipment. It is extremely useful for remote or hazardous locations.  Control functions may be manual, automatic or can be initiated by operator commands.

SCADA Main Components
Field Instrumentation and Control Equipment
Communications Network (Radio, Wire, VSAT)
Remote Terminal Unit (RTU) or Remote Stations (RS)
Central Monitoring Station (CMS)

Components of A SCADA System
The Field Instrumentation or equipment refers to the sensors, meters and/or actuators, valves, relays or motors that are directly interfaced with the plant, equipment, pipeline, etc.  It is this equipment that will generate the analog and/or digital signals that will be monitored at the Remote Station. The signals are designed for compatibility with the RTU (Remote Terminal Unit) or PLC (Programmable Logic Control) located at the remote stations
The Remote Station is located at the remote plant, equipment, monitoring station, etc. that is being monitored and controlled at the Central Monitoring Station's computer(s).  The remote station can consist of either an RTU or PLC unit(s).
The Communication Network is the communication medium(s) that are utilized for the transfer of data (information) within the SCADA network system. The communication network can consist of wire lines, radio, cable or satellite VSAT terminals.
The Central Monitoring Station (CMS) is the central monitoring and control station within the SCADA network system. The system can consist of one or several control/monitoring workstations.  The Man Machine Interface (MMI) program provides the link between the operator and the SCADA network system for both monitoring and control of the system.

- H.M.S. Telecom LLC SCADA Solutions

H.M.S. Telecom LLC SCADA Solutions