OBD2

There are physical addresses for one-to-one communication and functional addresses for one-to-many communication. Physical and functional addresses are composed of four different addressing formats The addressing formats consist of N_AI, N_TAtype, N_TA, N_SA, and N_AE. However, they may or may not be used depending on the addressing format.

To determine the sampling points, the number of quantums in each segment must be determined. There are 4 types of segments, each for 1 bit. Synchronization Segment. Propagation Segment. Phase Segment1. Phase Segment2. Propagation Segment + Phase Segment1 is called tseg1, and Phase Segment2 is called tseg2

Basically, a Google search can provide information on the CAN data link layer. CAN baud rate setting is special. It is not possible to set the baud rate directly, but the quantum time, which is a decomposition of 1 bit, is determined first. Since the total quantum is the baud rate, it is necessary to calculate backward from the baud rate you want to set. CAN can adjust the sampling point. It can be decided at which quantum in the total quantum to sample. This is often expressed as [%]. 50[%] for the middle, 75[%] for slightly behind (around 3/4).

The required standard numbers were reviewed. CAN has become a relatively common specification, and you can find information there on the Internet and in books. 1 Mbps is not often used in DoCAN. For legal reasons 1Mbps lacks stability in some aspects.

The typical standards for vehicle diagnostic communication are ISO 15765-2 and ISO 14229-1. Depending on the manufacturer's policy, the standard number may be a requirement rather than a specific requirement. The layers of vehicle diagnostic communication can be represented by the OSI model. There are two main axes of vehicle diagnostic communication. UDS and OBD. OBD is referenced by vehicle emission regulations, so the various parameters are clear. UDS only has recommended values, and the actual values are dependent on the finished vehicle manufacturer.

車両診断通信についていろいろ語っていく系のバックナンバー。 DoCAN概要。 CAN。 ISO-TP。 CanTpシミュレーション。 UDS。 Dcmシミュレーション。 CAN-FD概要。 python-canでCAN-FD。 CAN-FDのISO-TP。 CAN-FDでAUTOSAR。

車両診断通信のレイヤについて。 車両診断通信のレイヤはOSI参照モデルで表現できる。 ただし、プレゼンテーション層は無い。 車両診断通信には大きく2つの軸がある。 UDSとOBD。 OBDは自動車排出ガス規制から参照されているため、各種パラメータが明確。 UDSは推奨値があるだけで、実際の数値は完成車メーカ依存。

自動車には診断通信機能というものが備わっている。 それについて語っていくシリーズもの。 車両診断通信の概要情報はググればOK。 代表的な規格はISO15765-2とISO14229-1。 完成車メーカの方針によっては具体的な要件ではなく、規格番号が要件ということもある。