The number of signal lines needed to communicate a plurality of data types and a plurality of data status levels is reduced and the system cost thereby reduced. A first function unit 1 and a second function unit 2 of the function units in an electronic device are connected by a signal bus 3 for communicating a plurality of data types and a plurality of data status values. The first function unit 1 and second function unit 2 each have a data table of status patterns assigning status values to the data types. The first function unit 1 converts the status pattern to conversion data by referring to the data table and sends the conversion data to the second function unit 2. The second function unit 2 reconverts the received conversion data to the status pattern by referring to the data table.