Industrial process variable transmitter with isolated power scavenging intrinsically safe pulse output circuitry

摘要

An industrial process variable transmitter includes a process variable sensor configured to sense a process variable. Measurement circuitry is coupled to the process variable sensor and provides a measured output as a function of the process variable. Output circuitry includes a loop connection configured to couple to a process control loop. An optical sensor receives the measured output from the measurement circuitry. A switching device applies pulses to the process control loop in response to an output from the optical sensor. Power supply circuitry powers the optical sensor, a comparator, and/or the switching device with power received from the process control loop and loop connection.

主权项

1. An industrial process variable transmitter, comprising:
a process variable sensor configured to sense a process variable; measurement circuitry coupled to the process variable sensor configured to provide a measured output as a function of the process variable; output circuitry, comprising:
a loop connection configured to couple to a process control loop;an optical sensor configured to receive the measured output from the measurement circuitry;a second optical sensor configured to receive the measured output from the measurement circuitry;a switching device configured to apply pulses to the process control loop in response to an output from the optical sensor;power supply circuitry configured to power the optical sensor with power received from a power source through the process control loop and loop connection; andwherein the optical sensor and the second optical sensor are configured to operate in a push/pull configuration.