Patent ID: 6971626
Filing Date: 2005-12-06
Classification: G05B

Abstract:
1. For a digital valve positioning system comprising a valve, a valve controller having a controller microprocessor and a controller memory, a valve actuator having an output coupled to the valve to control the position of the valve over a range of motion in response to an output from the valve controller, and a first position sensor for determining the position of the valve actuator, an intelligent limit switch for generating a limit switch state signal indicative of a state of the valve being above or below a threshold set point, the limit switch comprising: a second position sensor generating an output signal indicative of the position of the valve; a limit switch memory; a limit switch microprocessor communicatively coupled to the limit switch memory; a communication link between the controller microprocessor and the limit switch microprocessor for transferring the set point data from the controller to the limit switch, wherein the limit switch microprocessor includes a first limit switch microprocessor output, the limit switch microprocessor being responsive to the second position sensor output signal and the set point data stored in the limit switch memory to generate the state signal at the first limit switch microprocessor output.