In order for a control loop to operate as desired, it must first be tuned. Tuning a control loop is the act of adjusting the values of proportional gain, integral gain, and derivative gain such that the process responds in a manner desired by the operator. There are two major methods of tuning a control loop: open and closed loop. Almost all technicians will use the closed loop method, where data is taken from an operating loop that is online. Open loop methods are more often used on the initial startup of a system and allow engineers to collect baseline data. This module will only cover closed loop tuning methods.