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US 5,870,695 AGranted
Differential pressure measurement arrangement utilizing remote sensor units
AssigneeRosemount Inc.
InventorsGregory C. Brown, David A. Broden
Life of this patent
Estimating the term…
Abstract
A master transmitter couples to first and second slave units through a bus. The slave units provide outputs to the bus related to first and second pressures of a process. The bus provides power to the units and carries signals. The master transmitter is adapted to couple to a two-wire process control loop which wholly powers the system.
Claims43
A pressure measurement transmitter for use in a process control system communicating with a control unit, comprising:
- a transmitter housing having an electrical connection to receive first and second respective electrical signals related to a first and second pressure;
- a first remote housing separated from the transmitter housing having a first pressure port therein;
- a second remote housing separated from the transmitter housing and the first remote housing having a first pressure port therein;
- a first and second pressure transducer disposed respectively in the first and second remote housing and providing respectively first and second transducer outputs indicative of pressure at the first and second pressure ports;
- slave circuitry in the first and second remote housings coupled to the first and second respective transducer outputs responsively providing first and second non-fluidic transducer signals;
- a non-fluidic communication link between the transmitter housing and the first and second remote housings for carrying the first and second non-fluidic pressure signal from the first and second remote housings to the electrical connection of the transmitter housing;
- and
- transmitter circuitry coupled to the control unit and disposed within the transmitter housing, the circuitry receiving the first and second non-fluidic transducer signal over the non-fluidic communication link, providing power to the slave circuitry over the communication link which wholly powers the slave circuitry and providing a transmitter circuitry output to the control unit over a two-wire process control loop as a function of the first and second transducer outputs wherein the transmitter and slave circuitry are wholly powered from the two-wire process control loop.
5 more elements
A pressure measurement transmitter in a two-wire process control loop, comprising:
- a first transducer housing having a first pressure port and a first communication port;
- a second transducer housing having a second pressure port and a second communication port;
- a transmitter housing having a third communication port;
- first and second pressure transducers disposed respectively in the first and second transducer housing and providing respectively first and second electrical outputs responsive to pressure at respectively the first and second pressure ports;
- and
- transmitter circuitry disposed in the transmitter housing and coupled to the first electrical output through the first communication port and to the second electrical output through the second communications port, the transmitter circuitry calculating a parameter related to pressures at the first and second pressure ports and providing a third electrical output indicative of the parameter and transmitting the calculated parameter over the two-wire process control loop through the third communication port, wherein the measurement transmitter is wholly powered from the two-wire process control loop.
3 more elements
A system for measuring a process variable related to a pressure differential in an intrinsically safe area, the system comprising:
- a first sensor unit including a first pressure sensor adapted to couple to the tank and responsively providing a first sensor signal related to a first pressure, and first conditioning circuitry coupled to the first sensor signal responsively providing a first unit output to a first unit connection which also receives power to wholly power the first sensor unit;
- a second sensor unit including a second pressure sensor adapted to couple to the tank and responsively providing a second sensor signal related to a second pressure, and second conditioning circuitry coupled to the second sensor signal responsively providing a second unit output to a second unit connection which also receives power to wholly power the second sensor unit;
- a bus coupled to the first and second unit connections which wholly powers the first and second sensor units and carries the first and second unit outputs;
- and
- a master transmitter connected to the bus to provide the power to the first and second units and adapted to be connected to a two-wire process control loop which wholly powers the transmitter and thereby the first and second sensor units, wherein the bus provides a non-fluid connection between the transmitter and the first and second units, the transmitter including transmitter circuitry which transmits a transmitter signal related to the process variable on the two-wire process in response to the first and second unit outputs received through the bus.
2 more elements
Dependencies are inferred from the claim text.