What is the normal instrument part of a control-loop?

The normal instrument part of a control loop typically includes sensors, controllers, and actuators. Sensors measure the process variable (e.g., temperature, pressure, or flow), while the controller processes this data and compares it to a setpoint to determine the necessary corrective action. Actuators then implement the controller's decisions by adjusting the process variable. This closed-loop system ensures that the process operates within desired parameters, maintaining stability and performance.