Patent ID: 7804843

Claim:
A communication apparatus comprising: a master unit; a plurality of sets of communication lines connected to the master unit; and a plurality of slave units connected to each of the plurality of sets of communication lines, wherein the master unit serially transmits data transmission request commands each of which specifies the master device as a subject for communications and makes a request for transmission of data to each of the plurality of sets of communication lines in synchronism with a clock of predetermined period, wherein each of the slave units determines whether it is the subject for communications on the basis of the data transmission request command, and in case of the subject for communications serially transmits the data corresponding to the data transmission request command to the master unit, wherein the master unit serially transmits the data transmission request commands at timings which are different in a predetermined time interval from each other among the sets of communication lines, wherein the master unit simultaneously communicates with the plurality of sets of communication lines, wherein the predetermined time interval is one half of a cycle period of the clock, and wherein the master unit, the sets of communication lines and the slave units are mounted on a vehicle so that the master unit activates airbags.