Vehicular communication device exchanging reception and transmission with external tool

A communicating method for a vehicular communication device that executes, by using a plurality of the buffers having ring buffer structure, at least one of reception of request and transmission of response with an external tool, the communication method comprising steps of:

• attaching, to each of the plurality of the buffers, each of a plurality of state signs based on each of a plurality of states, wherein each of the plurality of the buffers is used for each of the plurality of the states;
• selecting, when the reception of the request is executed, a given buffer from the plurality of the buffers based on a given state sign of the plurality of the state signs, wherein the given state sign is attached to the given buffer;
• attaching to the given buffer a relevant state sign of the plurality of the state signs based on a relevant state of the plurality of the states, wherein the given buffer is to be used for the relevant state;
• and
• using the given buffer.

A ring buffer used and controlled by a vehicular communication device that executes at least one of reception of request and transmission of response with an external tool, the ring buffer comprising:

• data area for storing the request and the response in common, the data area having a plurality of memory units whose addresses are formed in uninterrupted ring structure;
• and
• state sign area for storing, based on a varying state for which the data area is used, a given state sign of a plurality of state signs,
• wherein the data area is selectively used according to the given state sign.