What is the primary function of a controller wire in an irrigation system?

The primary function of a controller wire in an irrigation system is to carry electrical signals from the controller to the valves. This wire transmits the signals that activate or deactivate the valves based on the programmed irrigation schedules determined by the controller. These signals ensure that the correct zones are irrigated at the appropriate times, allowing for efficient water management and distribution throughout the irrigation system.

While the other options present functions related to irrigation systems, they do not accurately describe the role of the controller wire. For instance, carrying water to the valves pertains to the supply lines, not the controller wire. Monitoring soil moisture levels typically involves sensors but does not involve the controller wire directly. Similarly, measuring system pressure is a function more related to pressure gauges or sensors rather than a controller wire. Therefore, the correct answer highlights the essential communication role that the wire plays within the irrigation system's overall functionality.