INDUSTRIAL PROCESS VARIABLE TRANSMITTER WITH ISOLATED POWER SCAVENGING INTRINSICALLY SAFE PULSE OUTPUT CIRCUITRY

摘要

An industrial process variable transmitter (20) includes a process variable sensor (30, 32) configured to sense a process variable. Measurement circuitry (154) is coupled to the process variable sensor (30, 32) and provides a measured output as a function of the process variable. Output circuitry (158) includes a loop connection configured to couple to a process control loop (160). An optical sensor (200) receives the measured output from the measurement circuitry (154). A switching device (190) applies pulses to the process control loop (160) in response to an output from the optical sensor (20). Power supply circuitry (192) powers the optical sensor (200), a comparator (214), and/or the switching device (190) with power received from the process control loop (160) and loop connection.