an electrohydraulic system includes a plurality of electrohydraulic devices individually controlled by microprocessor - based control electronics . the device controllers are connected in common by a bidirectional serial data bus to a master controller for coordinating operation of the various devices . internal programming within the master controller establishes a repetitive time - sequence of windows for communications with the various device controllers for downloading control signals and parameters , and for uploading data indicative of system status and operation . the various device controllers include internal programming for operating the associated hydraulic devices as a function of control signals and parameters received from the master controller . pseudo - devices are also connected to the bus for time - division multiplexed communication with the master controller and for performing overall system coordination and analysis .