Vehicle based LAN a communication buffer memory having at least one more number of storage areas for receive status and source address than the number of areas for receive data

A primary object is to provide a communication apparatus, in particular, its buffer memory which conforms mainly to specifications of SAE-J1850 or ISO-9141. In the buffer memory, there are provided: at least, one more status registers storing information associated with the state of respective information to be transmitted and received, than the number of buffers storing information to be transmitted and received; at least, the same number of transmission error registers storing information associated with the transmitting state of information to be transmitted, as the buffers storing information to be transmitted; at least, one more receiving error registers storing information associated with the receiving state of information to be received, than the buffers storing information to be received; at least, one more source address registers storing information associated with the other communication apparatus which has transmitted respective information to be received, than the buffers storing information to be received; and at least, the same number of response information registers storing information responded from the communication apparatus which is to receive information when the information to be transmitted is transmitted, as the buffers storing information to be transmitted.