PURPOSE: To quicken the communication speed by transferring the sequence of data transmission to a succeeding node after the laps of time by one idle bit and sending the data sequentially without data transmission from its own node when its own node has no transmission data.

CONSTITUTION: A data reception section 3 of each node connected to a bus 1 always receives a data on the bus, a synchronous frame detection processing section 8 detects a #1 subframe (synchronous frame) on a superframe to take frame synchronization and an address detection processing section 9 detects an address from a succeeding subframe. Then an idle bit detection section 10 detects an idle bit succeeding to the subframe to recognize the data transmission timing of its own node. When its own node sends a data after the idle bit, a node succeeding to its own node takes over the data transmission after a reference idle bit + 1 bit. Thus, the communication speed is quickened.