In an electronic control system for a construction machine, a governor
control unit, an excavator body control unit, and an electric lever
control unit are interconnected for transmission and reception of data. A
universal communication line is connected to the governor control unit
and is adapted for an interface in conformity with universal
communication standards A dedicated communication line is connected to
the excavator body control unit and the electric lever control unit and
is adapted for an interface in conformity with dedicated communication
standards different from the univeral communication standards. A
communication relay control unit is used for, converting and transmitting
communication data received from one of two systems of the communication
lines to be in conformity with the communication standards of the other
communication line.