Patent ID: 6172615
Filing Date: 2001-01-09
Classification: G08C

Abstract:
A field bus systems comprising:a plurality of field instruments;a host instrument;a power source;a transmission line, at least a portion of which forms a current loop for connecting said field instruments, said host instrument, and said power source; anda communicator for communicating with said field instruments to monitor their status and communicating with said host instrument to inform said host instrument of the status of said field instruments;wherein said communicator communicates with said field instruments and said host instrument using digital electrical signals,wherein said transmission lines carries said digital electrical signals among said field instruments, said host instrument and said communicator,wherein said transmission line has means for connecting said communicator in series to said transmission line,wherein electrical power for operating said communicator is derived from said current loop, andwherein said field instruments are connected in parallel with one another along said current loop and transmit a measured physical quantity to said host instrument via said transmission line in digital signals.