Which of the following statements is true about the two common modes of controllers?

The distinction between the two common modes of controllers often revolves around their primary functions during operation. The Run mode is where the controller actively manages and monitors the process, executing the programmed control logic to ensure that the system operates as intended. In this mode, the controller receives input signals from sensors and provides outputs to actuators, thereby maintaining the desired state of the process.

The Test mode, on the other hand, is utilized for diagnostics, troubleshooting, or validation purposes. During this mode, the controller can simulate or test the functionality of its output without affecting the actual process. This can be crucial for ensuring that the system operates correctly before deploying it into production or after modifications and maintenance have occurred.

By understanding the roles of these two modes, one can see how they relate to various operational scenarios. This knowledge is fundamental in advanced PLC applications, particularly in industries where reliability and performance can significantly impact operations. The combination of Run and Test modes represents a balance between operational efficiency and ensuring the system's integrity, making the choice accurate and relevant to the question posed.