Critical Infrastructure Protection in Homeland Security: Defending a Networked Nation, 2nd Edition

10Supervisory Control and Data Acquisition

SCADA is an acronym for supervisory control and data acquisition. SCADA systems are composed of computers, networks, and sensors used to control industrial processes by sensing and collecting data from the running process, analyzing that data to determine how best to control it, and then sending signals back through a network to adjust or optimize the process. A number of definitions exist. We chose the following, because it is operational and descriptive:

An industrial measurement and control system consisting of a central host or master (usually called a master station, master terminal unit or MTU); one or more field data gathering and control units or remotes (usually called remote stations, remote terminal units, or RTU’s); and a collection of standard and/or custom software used to monitor and control remotely located field data elements. Contemporary SCADA systems exhibit predominantly open-loop control characteristics and utilize predominantly long distance communications, although some elements of closed-loop control and/or short distance communications may also be present.¹

The terms SCADA, industrial control system–SCADA (ICS–SCADA), energy management system (EMS), and distributed control systems (DCS) are often used interchangeably, but the term SCADA is usually reserved for systems that are geographically dispersed. Because SCADA computers and networks monitor and control industrial systems, they are a special type of ...