OBD接口的通信协议

liaojunzhi

谁有各种车型的OBD接口的通信协议类型? 是不是用一品牌的车都用同一种协议?或者同一款发动机不同车系它也是用同一协议?请高手指点.

teamk

回复 1# liaojunzhi

有五种，常用的是后两种
There are five signaling protocols that are permitted with the OBD-II interface. Most vehicles implement only one of
the  protocols.  It  is  often  possible  to  deduce  the  protocol  used  based  on  which  pins  are  present  on  the  J1962
connector:
•   SAE J1850 PWM (pulse-width modulation - 41.6 kB/sec, standard of the Ford Motor Company)
•   pin 2: Bus+
•   pin 10: Bus–
•   High voltage is +5 V
•   Message length is restricted to 12 bytes, including CRC
•   Employs a multi-master arbitration scheme called 'Carrier Sense Multiple Access with Non-Destructive
Arbitration' (CSMA/NDA)
•   SAE J1850 VPW (variable pulse width - 10.4/41.6 kB/sec, standard of General Motors)
•   pin 2: Bus+
•   Bus idles low
•   High voltage is +7 V
•   Decision point is +3.5 V
•   Message length is restricted to 12 bytes, including CRC
•   Employs CSMA/NDA
•   ISO 9141-2. This protocol has an asynchronous serial data rate of 10.4 kBaud. It is somewhat similar to RS-232,
however the signal levels are different, and communications happens on a single, bidirectional line without
additional handshake signals. ISO 9141-2 is primarily used in Chrysler, European, and Asian vehicles.
•   pin 7: K-line
•   pin 15: L-line (optional)
•   UART signaling
•   K-line idles high, with a 510 ohm resistor to V
batt
•   The active/dominant state is driven low with an open-collector driver.
•   Message length is restricted to 12 bytes, including CRC
•   ISO 14230 KWP2000 (Keyword Protocol 2000)
•   pin 7: K-line
•   pin 15: L-line (optional)
•   Physical layer identical to ISO 9141-2
•   Data rate 1.2 to 10.4 kBaud
•   Message may contain up to 255 bytes in the data fieldOn-board diagnostics 5
•   ISO 15765 CAN (250 kBit/s or 500 kBit/s). The CAN protocol was developed by Bosch for automotive and
industrial control. Unlike other OBD protocols, variants are widely use outside of the automotive industry. While
it did not meet the OBD-II requirements for U.S. vehicles prior to 2003, as of 2008 all vehicles sold in the US are
required to implement CAN as one of their signaling protocols.
•   pin 6: CAN High
•   pin 14: CAN Low
All OBDII pinouts use the same connector but different pins are utilized with the exception of pin 4 (battery ground)
and pin 16 (battery positive).

teamk

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