PURPOSE: To simplify the state recognition of slave nodes in a master node and to reduce power consumption in the communication system of a polling/ selecting system constituted of the master node and the plural slave nodes.
CONSTITUTION: When a first specific message indicating that the slave node 3 is started collides with the other messages and can not be received normally, the master node 10 transmits a third specific message to the respective slave nodes 1-3 as a multi-address message. Then, the master node 10 successively transmits a second specific message to the respective slave nodes 1-3, receives response messages and recognizes the states of the slave nodes 1-3. Also, at the time of turning into a power saving mode, the master node transmits that effect to the respective slave nodes 1-3 as the multi-address message. Then, when data to be transmitted by the slave node 2 is generated, the specific message is transmitted. When the specific message is received, the master node 10 cancels the power saving mode.
SHIMADA KAZUTOSHI
TATSUMI EISAKU
SUNAKAWA SHINICHI
NAGASAKI KATSUHIKO
