Abstract

An energy management controller is coupled via a clock line pair, a "data out" line pair and a "data in" line pair, to a plurality or group of stations each having energy using equipment. Each station is electrically coupled to each line pair at spaced points along the line pairs. Each station counts the number of clock bits from the controller. After each group of a predetermined number of clock bits are received, each station provides an address count that is incremented by one after each group of clock bits are received. By setting each station to a different address count and enabling each station to transmit and receive data only during its respective address count period each station can be individually accessed by the controller without specifically addressing each station. During the address count period for each station serial bits are transmitted to and received from that station by the controller for actuation and control of the energy using equipment for that station. Use of the clock line enables each station control to synchronize and therefore communicate with the controller even though the controller has an aperiodic and unpredictable response time between receiving data from and transmitting data to the station controls. Information gathered at each station control is digitized at the station control for transmission to the controller.