A building automation system (BAS) comprising a plurality of end devices, at least one communication network, and a server engine comprising a communication state manager for actively managing the state of various devices in building automation system and an associated reconnect manager to reestablish communication with off-line devices. The communication manager and the reconnect manager coordinate the interaction between the server engine and the devices in order to minimizing the load on the communication network, while also working to establish the working state of any of the end devices and to transition off-line to an on-line state.