A control system is a system that uses a control loop to manage and control another device or system. The control system can be as small as a home temperature controller implemented with a thermostat, or as large as a large industrial control system that controls a process or machine.

If connected to a regulated control system, a feedback controller is used to automatically control the process or action. The control system will compare the process variable (PV) to be controlled with the ideal value or target value (SP), and use the difference to generate a control signal, so that the process variable to be controlled can return to the target value.

For sequential logic circuits and combinational logic circuits, devices (such as programmable logic controllers) are used to implement their algorithms