To provide an onboard communication system which can maintain high communication efficiency by maintaining the number of connected nodes.
The onboard communication system mounted on a vehicle includes a bus line for connecting a plurality of nodes attached to the vehicle, a first node attached to the vehicle and connected to the bus line, a relay circuit for switching connection/disconnection state between the first node and the bus line, a second node prepared on the outside of the vehicle, and a connector for connecting the second node to the bus line. The first node includes an external node connection determining means for determining whether the second node is connected to the bus line or not and a relay control means for cutting the connection between the bus line and the first node by controlling the relay circuit when it is determined that the second node is connected to the bus line.
SUGINO KIMIHIKO
SUZUKI TOMONORI
Takeji Takada