US Patent 11181403 Process variable sensor testing

A process transmitter includes a process variable sensor, a test circuit, a switch and a controller. The process variable sensor includes a sensor output that is indicative of a sensed process variable. The test circuit is configured to detect a condition of the process variable sensor. The switch is configured to selectively connect the test circuit to the process variable sensor and disconnect the test circuit from the process variable sensor. The controller is configured to obtain a measurement of the process variable, control the switch, detect a condition of the process variable sensor by comparing the sensor output when the test circuit is connected to the process variable sensor to the sensor output when the test circuit is disconnected from the process variable sensor, and communicate the condition in the measurement to an external control unit.