Rosemount Inc.

Paul D Kammann

Kevin B Moore

Stephen D Anderson

Gabriel A Maalouf

Daniel V Hulse

Bruce B Davis

A method and apparatus are provided to allow at least portions of two fieldbus messages to be stored in a fieldbus device. The fieldbus device includes a media access unit, a fieldbus communication controller, and a controller. The media access unit is coupleable to a fieldbus loop to receive fieldbus signals and provide a digital bitstream related to the fieldbus signals. The fieldbus communication controller assembles data segments relating to at least portions of two fieldbus messages from the bitstream and stores the segments in a receive FIFO memory. The controller is adapted: to read the segments from the receive FIFO memory and act upon fieldbus messages.

Fieldbus message queuing method and apparatus

A receiver receives modulated message signals in non-coherent FSK and coherent 8PSK protocols. A selectively configurable processor demodulates the message signals, and includes a demodulator that derives in-phase and quadrature signals based on the message signals. A phase detector is responsive to the in-phase and quadrature signals and delayed in-phase and quadrature signals to derive a phase signal. A selector is responsive to the in-phase and quadrature signals to selectively connect a loop filter between the phase detector and the demodulator. When the selector connects the filter between the phase detector and demodulator, the demodulator is responsive to filtered phase signals to lock onto a frequency of the message signals so that the processor operates as a phase locked loop to demodulate coherent modulated signals. When the selector disconnects the filter from between the phase detector and the demodulator, the demodulator demodulates non-coherent modulated signals and the phase detector supplies a phase signal representing the slope of the phase of the demodulated signal.

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Golden Valley, MN, United States of America

Paul D Kammann