Patent ID: 7710951

Claim:
Signaling method for a network system, wherein a control unit communicates over a wired signaling channel with at least one nodal unit, each one of said nodal units being associated with at least one device to be monitored, and in which method the signaling is carried out over the signaling channel between each nodal unit and the control unit, the method comprising: feeding a common analog read signal, which is a direct-current voltage signal of a desired level, to all nodal units via the signaling channel under control of the control unit; serially reading the states of the nodal units one by one without a separate clock signal so that, at each nodal unit, the propagation of the direct-current voltage signal to the next nodal unit is delayed, by a modification unit, for a time exceeding the duration of the read operation whereby a different delay is associated with each nodal unit; and setting, within a predetermined read time window determined by a delay unit, the value of the electric current produced by the direct-current voltage signal in each nodal unit to a level corresponding to the state of the nodal unit according to the nodal unit's impedance across which the direct-current voltage signal is applied; and determining the state of each nodal unit in the control unit in serial mode based on the intensity value of the electric current signal received according to the different delays from each nodal unit, or setting the nodal unit to a desired state to control with a switch connected to the nodal unit.