RF adapter for field device with variable voltage drop

摘要

A wireless adapter for use in a two-wire process control loop includes wireless communication circuitry and first and second terminals configured to couple in series with the two-wire process control loop. A regulator having a regulated input is coupled to the first terminal and an output. A shunt is coupled to the output of the regulator and is configured to provide power to the wireless communication circuitry. A feedback circuit is configured to control current flowing from the regulator to the shunt as a function of a loop current flowing through the two-wire process control loop.

主权项

1. A wireless adapter for use in a two-wire process control loop configured to couple to a process field device in an industrial process control system coupled to the two-wire process control loop and provide wireless communication to the process field device, comprising:
wireless communication circuitry; first and second loop terminals configured to couple in series with the two-wire process control loop and a process variable transmitter the first and second loop terminals carrying a loop current therebetween, the loop current powering the wireless adapter and carrying information; a switching regulator having a switching regulator input coupled to the first loop terminal and an output; a shunt regulator coupled to the output of the regulator configured to provide power to the wireless communication circuitry; and a feedback circuit configured to control current flowing from the switching regulator to the shunt regulator as a function of a loop current flowing through the two-wire process control loop as measured through at least one of the first and second terminals wherein the feedback circuit is configured to control a voltage drop across the first and second terminals.