A typical ICS contains numerous control loops, human interfaces, as well as remote diagnostics and maintenance tools. They are built using an array of network protocols on layered network architectures, allowing ICS support staff and vendors access to diagnose and correct operational problems.
A control loop, single-loop control is the fundamental building block of industrial control systems. It is communication used to regulate the process. It consists of a group of components working together as a system to achieve and maintain a desired value of a system variable by manipulating the value of another variable in the control loop.
For example, a field device sensor produces a measurement of a physical property and sends this information as controlled variables to the controller. The controller interprets the signals and generates corresponding manipulated variables, based on set points, which it transmits to the actuators (field devices), such as control valves, breakers, switches, and motors. These field devices are used to directly manipulate the controlled process based on commands from the controller. Control can be fully automated or include a human in the loop.
Copyright: Cybersecurity & Infrastructure Security Agency (CISA)