What is the primary step in a control loop?

The primary step in a control loop is to measure the process variable. This is essential because the control loop relies on accurate data about the current state of the system to function effectively. By measuring the process variable, the control system can determine the current value of the variable that is being controlled, such as temperature, pressure, level, or flow rate.

Once the measurement is taken, it can then be compared to the desired setpoint to evaluate whether any adjustments are needed. This initial measuring step is foundational, as it provides the information necessary for the subsequent actions in the control loop, such as making comparisons, adjustments, and transmitting data. Without accurate measurement, the control system cannot properly assess its performance or make informed decisions to adjust the process variable toward the setpoint.