Patent ID: 7687791

Claim:
An Ethernet data signal transmission apparatus comprising: a non-intrinsically safe Ethernet cable, a first media converter, an optical data signal transmission means, a second media converter, an intrinsically safe Ethernet cable and an intrinsically safe power supply, in which the non-intrinsically safe Ethernet cable comprises a data output line and a data input line, each comprising a pair of positive and negative data cores, in which the first media converter is connected to said data output line and data input line of the non-intrinsically safe Ethernet cable and is adapted to convert outgoing Ethernet data signals from said data output line of the non-intrinsically safe Ethernet cable into outgoing optical data signals for the optical data signal transmission means, and to convert incoming optical data signals from the optical data signal transmission means into incoming Ethernet data signals for said data input line of the non-intrinsically safe Ethernet cable, in which the optical data signal transmission means is adapted to transmit said outgoing and incoming optical data signals over an electrical isolation gap, in which the intrinsically safe Ethernet cable comprises a data output line and a data input line, each comprising a pair of positive and negative data cores, in which the second media converter is connected to said data output line and data input line of the intrinsically safe Ethernet cable and is adapted to convert said outgoing optical data signals from said optical data signal transmission means back into outgoing Ethernet data signals for the data output line of the intrinsically safe Ethernet cable, and to convert incoming Ethernet data signals from the data input line of the intrinsically safe Ethernet cable into incoming optical data signals for the optical data signal transmission means, in which the second media converter is powered by the intrinsically safe power supply, in which the data output line and the data input line of the intrinsically safe Ethernet cable are provided with current limiting means comprising one or more current limiting resistors, and in which the current limiting resistors are disposed symmetrically about the four positive and negative cores of the intrinsically safe Ethernet cable.