Patent ID: 7454252

Claim:
An apparatus for use in a redundant fieldbus system, the apparatus comprising: first terminals adapted to connect to a first fieldbus cable, the first terminals coupled to a field device to provide power and communications from a fieldbus network to the field device; second terminals adapted to connect to a second fieldbus cable, the second terminals coupled to the field device to provide power and communications from the fieldbus network to the field device; and isolation circuitry connected between the first terminals and the field device and connected between the second terminals and the field device, the isolation circuitry adapted to provide power from either the first terminals or the second terminals to the field device, the isolation circuitry further adapted to isolate a short circuit between the first terminals from a power source connected to the field device through the second; and wherein the apparatus provides independent current paths between the first terminals and the field device and between the second terminals and the field device, the apparatus further comprising first and second spur connection circuits.