公开(公告)号：DE69420853D1

公开(公告)日：1999-10-28

申请号：DE69420853

申请日：1994-07-29

Applicant: ROSEMOUNT INC

Inventor： LOUWAGIE BENNETT ,  MUNSON GREGORY ,  WIKLUND DAVID ,  ZWEBER MICHAEL ,  BRODEN DAVID ,  BISCHOFF BRIAN ,  CORPRON GARY

IPC: G01F1/36 ,  G01F1/88 ,  G01F15/06 ,  G01F23/14 ,  G01F23/18 ,  G01L7/08 ,  G01L9/04 ,  G01L19/00 ,  G01L19/08

Abstract: A two-wire transmitter senses a pressure using an internal pressure sensor. The transmitter includes an input for receiving a process variable from a remote sensor which is separated from the transmitter. Circuitry in the transmitters transmits information on a two-wire process control loop which is related to the sensed pressure and the process variable.

公开(公告)号：DE69319430T2

公开(公告)日：1999-02-25

申请号：DE69319430

申请日：1993-05-17

Applicant: ROSEMOUNT INC

Inventor： FRICK ROGER ,  MUNSON GREGORY

IPC: G01L9/00 ,  G01L9/06 ,  G01L9/12 ,  G01L13/06 ,  G01L19/00 ,  G01L19/02 ,  G01L19/04 ,  G01L19/08 ,  G01L27/00

Abstract: A two-wire transmitter includes a pressure sensor comprising first and second sensing means each having an impedance value which varies with pressure being measured and with a predetermined environmental condition, such as line pressure or temperature. A fixed impedance has an impedance value which is substantially unchanged by variations in the predetermined environmental condition. A switch alternately connects the fixed impedance into operative relation with the first and second sensing means to derive first and second signals which are each functions of pressure being measured and the predetermined environmental condition. A correction circuit processes the first and second signals, such as by a polynomial series or with a lookup table, to derive a corrected pressure signal. In one form, the sensor senses differential pressure and the predetermined environmental condition is line pressure or temperature, and the first and second signals are functions of both differential pressure and either line pressure or temperature, so the correction circuit derives an indication of differential pressure corrected for variations in either line pressure or temperature. In another form, the sensor measures line pressure and is sensitive to temperature changes, in which case the first and second signals are functions of line pressure and temperature and the correction circuit derives a line pressure signal corrected for variations in temperature.

公开(公告)号：DE69420853T2

公开(公告)日：2000-05-18

申请号：DE69420853

申请日：1994-07-29

Applicant: ROSEMOUNT INC

Inventor： LOUWAGIE BENNETT ,  MUNSON GREGORY ,  WIKLUND DAVID ,  ZWEBER MICHAEL ,  BRODEN DAVID ,  BISCHOFF BRIAN ,  CORPRON GARY

IPC: G01F1/36 ,  G01F1/88 ,  G01F15/06 ,  G01F23/14 ,  G01F23/18 ,  G01L7/08 ,  G01L9/04 ,  G01L19/00 ,  G01L19/08

Abstract: A two-wire transmitter senses a pressure using an internal pressure sensor. The transmitter includes an input for receiving a process variable from a remote sensor which is separated from the transmitter. Circuitry in the transmitters transmits information on a two-wire process control loop which is related to the sensed pressure and the process variable.

公开(公告)号：DE69319430D1

公开(公告)日：1998-08-06

申请号：DE69319430

申请日：1993-05-17

Applicant: ROSEMOUNT INC

Inventor： FRICK ROGER ,  MUNSON GREGORY

IPC: G01L9/00 ,  G01L9/06 ,  G01L9/12 ,  G01L13/06 ,  G01L19/00 ,  G01L19/02 ,  G01L19/04 ,  G01L19/08 ,  G01L27/00

Abstract: A two-wire transmitter includes a pressure sensor comprising first and second sensing means each having an impedance value which varies with pressure being measured and with a predetermined environmental condition, such as line pressure or temperature. A fixed impedance has an impedance value which is substantially unchanged by variations in the predetermined environmental condition. A switch alternately connects the fixed impedance into operative relation with the first and second sensing means to derive first and second signals which are each functions of pressure being measured and the predetermined environmental condition. A correction circuit processes the first and second signals, such as by a polynomial series or with a lookup table, to derive a corrected pressure signal. In one form, the sensor senses differential pressure and the predetermined environmental condition is line pressure or temperature, and the first and second signals are functions of both differential pressure and either line pressure or temperature, so the correction circuit derives an indication of differential pressure corrected for variations in either line pressure or temperature. In another form, the sensor measures line pressure and is sensitive to temperature changes, in which case the first and second signals are functions of line pressure and temperature and the correction circuit derives a line pressure signal corrected for variations in temperature.