An electrohydraulic system which includes a plurality of electrohydraulic devices individually controlled by microprocessor-based control electronics. A central controller for coordinating operation among the various devices includes a host controller for providing low speed serial and/or parallel output of control signals, and a master controller having a low speed serial and parallel I/O port for connection to the host controller, and a high speed serial I/O port connected by a full duplex bidirectional data bus in common to all of the device controllers.