Multiplex-Kommunikationssystem

摘要

A multiplex communication system, for example in a vehicle, has a plurality of node devices 1 to 11 connected via a bus line 21 to at least one of a plurality of end node devices to be controlled 12 to 15. As the number of nodes increases, the delays involved in transmitting data along the bus can become unacceptably long. Therefore, the data is divided into a plurality of categories according to the necessity of transmission. For example, engine management data that needs to be transmitted more urgently than door mirror control data has a higher necessity of transmission. The more urgent data is transmitted once every multiplex transmission cycle, while the less urgent data is transmitted once every few transmission cycles, according to the necessity of transmission. This reduces the delays. Alternatively, the transmitting and receiving nodes can be identified without having to append address data to the message data. One of node devices serving as the master node device M sets the transmission cycle of message data transmitted onto the bus line 21 as a cycle of a start pulse that is sent to the bus line 21. This cycle has been set so as not to cause a time lag in data processing executed by the respective node devices. Each time interval between the start pulses is divided into a plurality of time slots. The time slots have been allocated to the individual node devices so that message data can be transmitted from the respective devices in the associated time slots without the need for address data, thereby reducing delays. <IMAGE>