A system for use in controlling a hydrocarbon production well has a: computer at a control location remote from a well tree of the well. A processor at the well tree applies control signals to and receives signals from devices of well tree. The processor also receives further signals associated with the operation of the well. A bi-directional communication link extends between the remote computer and the well tree processor. The well tree further has a communications router coupled with the processor and receiver, for multiplexing the signals from devices at the well head and the further signals on to the bi-directional link.