The present disclosure describes an HVAC system and means for communication between an integrated system of individual controllers for interactively controlling various components in the HVAC system. When data is received it is written to the first block, and in parallel some of the data is written to the second block, so that the second block is partially programmed. A temporal period is determined during which a predetermined condition will affect communications with the second terminal; the predetermined condition can be, for example, a period during which the sun will be within a predetermined subtended angle of an antenna associated with the second terminal. Since the data and control and addressing lines are separate, the control may act concurrently with the data to direct the data properly. The shifted line of data is written over the previous line so that the lower order bytes of the shifted received line of data are written. Directives for content manipulation are also delivered securely.