Method and system for automatically identifying CAN communication baud rate of vehicle ECU

Abstract

The invention discloses a method for automatically identifying a CAN communication baud rate of a vehicle ECU. The method comprises the steps that S101, vehicle-mounted equipment sets an initial baudrate; S102, the vehicle-mounted equipment carries out silence monitoring on a vehicle OBD interface through the current Baud rate; S103, if the register in the vehicle-mounted equipment reports an error, the baud rate is switched and step S102 is performed; if the register in the vehicle-mounted equipment does not report the error, step S104 is executed; S104, the vehicle-mounted equipment is switched from silent monitoring to normal monitoring, an invalid message is sent to the vehicle ECU, a correct baud rate is identified if the register does not report an error, the baud rate is swithed and step S102 is executed if the register reports the error. According to the method for identifying the baud rate, data communication on an original CAN bus network is not influenced, and the method is rapid and stable.

Description

technical field [0001] The invention belongs to the technical field of vehicle diagnosis, in particular to a method for automatically identifying the CAN communication baud rate of a vehicle ECU. Background technique [0002] Nowadays, people's demand for monitoring the status of vehicles is increasing, including the national mandatory vehicle emission monitoring requirements and the active monitoring of vehicle conditions by enterprises or individuals. Therefore, more and more vehicle-mounted terminal devices are used in vehicles. In most cases The vehicle-mounted terminal equipment (such as T-BOX) and the vehicle's ECU are connected through the OBD physical interface, and the CAN line in the OBD interface is used to obtain the information that the vehicle ECU can provide. Before obtaining information through CAN, it is necessary to determine the CAN communication rate. Baud rate, the wrong baud rate is unable to communicate, and for the vehicle terminal equipment, the baud...

AI Technical Summary

Problems solved by technology

At present, the general baud rate automatic matching technology mainly involves two types, one is monitoring, that is, the vehicle equipment sets the baud rate, and then monitors the OBD interface. If the data is received, it can be determined that the current baud rate is the correct baud rate. The serious disadvantage of this method is that if there is no data transmission on the CAN channel on the OBD interface, the correct baud rate cannot be recognized and the original data transmission in the CAN bus network will be destroyed.

The other is that the on-board equipment actively sets different baud rates to send data to the CAN bus network. If the transmission is successful, it will determine that the currently used baud rate is the correct baud rate. The disadvantage of this method is that it will destroy the CAN bus. Original data transmission in the network

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