Analog process variable transmitter with electronic calibration
AssigneeRosemount Inc.
InventorNathan Len Wiater
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Abstract
A process variable transmitter for measuring a process variable includes a process variable sensor configured to sense a process variable and provide a sensor output. Measurement circuitry receives the sensor output and provides a measured output related to the process variable. Output circuitry provides a device output on a two-wire process control loop based upon the measured output. The output circuitry has a transfer function that is a function of an adjustable analog circuit component. A motorized actuator is configured to adjust the adjustable analog circuit component to thereby change the transfer function of the output circuitry. An optional calibration controller is also provided.
Claims23
A process variable transmitter for measuring a process variable, comprising:
- a process variable sensor configured to sense a process variable and provide a sensor output;
- measurement circuitry configured to receive the sensor output and provide a measured output related to the process variable;
- output circuitry configured to provide a device output on a two-wire process control loop based upon the measured output, the output circuitry having a transfer function that is a function of an adjustable analog circuit component;
- and
- a motorized actuator configured to adjust the adjustable analog circuit component to thereby change the transfer function of the output circuitry.
A method of calibrating a process variable transmitter of the type used to measure a process variable, comprising:
- sensing a process variable with a process variable sensor;
- measuring the sensed process variable;
- providing a device output on a two-wire process control loop based upon the measured process variable and a transfer function of output circuitry;
- and
- changing the transfer function of the output circuitry using a motorized actuator which adjusts an adjustable analog circuit component of the output circuitry.
Dependencies are inferred from the claim text.