INTELLIGENTER VENTILPOSITIONIERER

摘要

A valve positioner controls operation of a valve in a process control system. The valve positioner is coupled to a process control loop over which it receives a signal representative of a desired valve position and operating power for the positioner. The valve positioner controls a pneumatic actuator which in turn controls position of the valve. The valve positioner includes a microprocessor, associated digital circuitry and analog circuitry. Low power analog circuitry performs PID control functions. The microprocessor periodically updates at least one digital control signal used to selectively program a resistance in the analog circuitry. The combination of digital and analog circuitry allows reduced power consumption because the analog PID function consumes less power and is performed more quickly than the microprocess could perform the same function.