Distributed Control System (DCS): These systems are used within a small geographic area, such as a manufacturing plant or nuclear reactor. A single vendor generally supplies the whole system: hardware, software, master control station, engineering workstation, programmable logic controllers (PLC), cabling and so on. A DCS is often connected over a LAN and may control the whole industrial process in a plant.Supervisory Control and Data Acquisition (SCADA): These systems are typically used throughout a wider geographic area to distribute products such as electricity or oil. SCADA systems have a master that communicates with remote devicesPLCs or remote terminal units (RTUs), for exampleover a cable, Internet, wireless, or a public or private switching networks. An electric grid might have hundreds (or thousands) of remote devices that control the distribution of electricity. The RTU collects real-time data and sends it to a master station, which then sends commands back to the RTU to perform its functions.