A control loop controller is designed to:

A control loop controller is primarily designed to continuously monitor and compare the process variable, which is the current condition of a system, to the desired set point, which represents the target value the system is trying to maintain. This ongoing comparison is essential for maintaining stable operation within the system.

When the controller identifies any deviation between the process variable and the set point, it generates corrective signals to the final control element (such as a valve or heater) to bring the process variable back towards the set point. This self-regulating feedback mechanism is at the heart of controlling processes in power engineering and other applications.

While a controller can influence a primary element and measure variables, its primary function revolves around the continuous comparison and adjustment process that ensures performance aligns with operational goals. Eliminating all deviations is more of an ideal situation rather than a functional capability of a control loop controller; some tolerance for deviation is generally accepted in real systems. Therefore, the key role of the controller remains its ability to assess the difference between current and target states, guiding actions to rectify any discrepancies.