What is the correct approach to verify the function and range of a final control element using a controller?

To verify the function and range of a final control element using a controller, altering the output directly through manual control is the most effective method. When you switch to manual mode and change the output, you can precisely observe how the final control element reacts to these changes without the influence of the control loop. This allows you to assess if the final control element is capable of reaching its full range of functionality, thereby verifying that it operates correctly across its intended range.

This approach provides a clear and direct way to evaluate not only the response of the final control element but also confirms if the entire control system—including the controller and final element—is functioning as expected under specified conditions. By doing this in manual mode, you are eliminating automated feedback responses that could mask or distort the true performance characteristics of the final control element.

Other methods, such as changing the set point or the process variable while in automatic mode, may not provide the same level of clarity regarding the final control element's performance. The auto tune option adjusts the controller parameters and may not specifically target the verification of the final control element's operational range. Thus, manual adjustment of the output offers a straightforward, effective means of evaluating the final control element.