The CCU acts as the system's “computer-in-the-field,” allowing control of hundreds of sites from one Central Controller. Schedules are automatically downloaded from the Central Controller to the Cluster Control Unit at a user-entered time. Commands are then sent from the CCU to the appropriate field satellites to control irrigation throughout the irrigation day. The CCU monitors site conditions constantly and takes action as needed; managing flow demand, pausing or canceling irrigation in the event of rain, etc., or locating and isolating the causes of excessive flow (broken heads or piping breaks). Irrigation data and information (flow logs, alarms, actions taken, etc.) are automatically uploaded to the Central Controller at a user entered time, usually after the irrigation cycle is complete. The CCU can monitor, communicate to, and manage as many as 28 ESP-Satellite controllers or other field devices via a two-wire (hardwire), wireless radio or Ethernet communications method.