PROCESS VARIABLE TRANSMITTER WITH SELF-LEARNING LOOP DIAGNOSTICS

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. 一种在工业过程中使用的两线过程变量变送器，包括过程变量传感器，被配置为感