A self-healing communications network including a network bus that connects a plurality of field controllers. Each field controller is configured to operate an element of a system installed in a building or similarly large structure, and each is connected to the network bus. An end-of-line resistor can be automatically enabled in any field controller to designate that field controller as a terminal device on the network bus. In an embodiment, a parent controller detects each field controller on the network bus, and monitors and controls operation of the plurality of field controllers via commands transmitted over the network bus. The parent controller has first and second receiver/transmitter ports, both connected to the network bus. The parent controller is configured to automatically repair a break in the network bus by enabling at least one end-of-line resistor in one of the plurality of field controllers in order to properly terminate the network.