Some novel μP-based configurations for controlling remotely located stepper motors as actuators of control valves

Four microprocessor based configurations for controlling remotely located stepper motors with single-step resolution control to work as actuators of control valves with a 4-20 mA control signal generated in a multichannel data acquisition and control system are investigated for their operations, performances, and limitations. One of the configurations is directly hardware compatible with that of electropneumatic valves, but for the other configurations, hardware interfaces are needed to store, generate, and transmit control signals in order to reduce microprocessor busy time. The detection circuits required at the remote end for deriving direction, stepping rate, and drive duration from the control signal become simple if the information about these is explicitly expressed in the control signal