Abstract: A microprocessor-based valve motor control system which provides control, predictive control and diagnostic functions for a motor operated valve. A microprocessor periodically tests the status of the motor operated valve, and turns off the valve's motor if certain predefined criteria for the valve stem position and the valve stem load are satisfied. The periodic testing by the microprocessor includes the testing of a position criterion (comparing both the current valve stem position signal and a predicted stem position with a preselected target position); and a stem load criterion (comparing both the current valve stem load and a predicted stem load with a preselected maximum desirable stem load).When the control system is being used with a gate valve for fully opening and fully closing a valve, the control logic can use either a predicted position criterion or a predicted stem load criterion to determine when to turn off the valve motor.