What is the true statement regarding the function of controllers?

Controllers play a crucial role in automated systems by continuously adjusting the inputs to a process in order to maintain the desired output level or setpoint. One of their primary functions is to perform a mathematical summation, which involves comparing the current process variable to the setpoint and calculating the necessary corrective action. This ensures that any deviations from the desired output are addressed, thereby maintaining the stability and effectiveness of the system.

In practical terms, this means that if the process variable (e.g., temperature, pressure, flow rate) moves away from the setpoint, the controller evaluates the difference and determines how much adjustment is needed. This corrective action can be implemented through various means, such as changing a valve position or adjusting the power to a heater, thus maintaining optimal operation.

While other aspects of control systems are relevant, such as measuring the process variable or displaying it for monitoring, the essence of controller functionality lies in its ability to analyze the information and make real-time adjustments through algorithms and calculations. Therefore, the statement regarding performing mathematical summation as part of correcting the process accurately captures the fundamental operation of controllers.