PROCESS VARIABLE TRANSMITTER WITH SELF-LEARNING LOOP DIAGNOSTICS
First Claim
1. A two-wire process variable transmitter for use in an industrial process, comprising:
- a process variable sensor configured to sense a process variable of a process fluid of the industrial process;
output circuitry configured to provide an output on a two-wire process control loop which is related to the sensed process variable;
terminal voltage measurement circuitry configured to measure a voltage related to a terminal voltage of the process variable transmitter, the terminal voltage comprising a voltage measured across an electrical connection of the two-wire process variable transmitter to the two-wire process control loop;
a microprocessor configured to perform loop diagnostics on the two-wire process control loop based upon a determined loop current and the measured terminal voltage, wherein the microprocessor determines coefficients of a polynomial equation which relates loop current and terminal voltage during normal operation of the two-wire process variable transmitter and performs subsequent diagnostics based upon the coefficients of the polynomial.
1 Assignment
0 Petitions
Accused Products
Abstract
A two-wire process variable transmitter for use in an industrial process includes a process variable sensor configured to sense a process variable of a process fluid of the industrial process. Output circuitry provides an output on a two-wire process control loop which is related to the sensed process variable. Terminal voltage measurement circuitry measures a voltage at terminals of the process variable transmitter. The terminal voltage is a voltage measured across an electrical connection of the two-wire process variable transmitter to the two-wire process control loop. A microprocessor performs loop diagnostics on the two-wire process control loop based upon a loop current and the measured terminal voltage. The microprocessor determines coefficients of a polynomial equation which relates loop current and terminal voltage during normal operation of the two-wire process variable transmitter and performs subsequent diagnostics based upon the coefficients of the polynomial.
63 Citations
24 Claims
-
1. A two-wire process variable transmitter for use in an industrial process, comprising:
-
a process variable sensor configured to sense a process variable of a process fluid of the industrial process; output circuitry configured to provide an output on a two-wire process control loop which is related to the sensed process variable; terminal voltage measurement circuitry configured to measure a voltage related to a terminal voltage of the process variable transmitter, the terminal voltage comprising a voltage measured across an electrical connection of the two-wire process variable transmitter to the two-wire process control loop; a microprocessor configured to perform loop diagnostics on the two-wire process control loop based upon a determined loop current and the measured terminal voltage, wherein the microprocessor determines coefficients of a polynomial equation which relates loop current and terminal voltage during normal operation of the two-wire process variable transmitter and performs subsequent diagnostics based upon the coefficients of the polynomial. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
-
-
17. A method of performing diagnostics in a two-wire process variable transmitter of an industrial process, comprising:
-
sensing a process variable of a process fluid of the industrial process; providing an output on a two-wire process control loop which is related to the sensed process variable; determining the loop current flowing through the two-wire process control loop; coupling terminal voltage measurement circuitry to terminals of the two-wire process variable transmitter, the terminal voltage measurement circuitry configured to measure a terminal voltage across terminals which are configured to couple to the two-wire process control loop; determining coefficients of a polynomial equation which relates the determined loop current to the measured terminal voltage during normal operation of the two-wire process control loop; and performing diagnostics on the two-wire process control loop based upon the determined coefficients. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
-
Specification