Multi-device controller area network (CAN) communication intelligent retransmission method

Abstract

The invention discloses a multi-device controller area network (CAN) communication intelligent retransmission method. Two sending mail boxes are arranged in each of CAN controllers, the first mail box is used for sending messages according to normal logic requirements, and the second mail box is used for sending retransmitted messages due to errors; according to the CAN controllers in a network, by means of a timing mode or an event triggering mode, the first mail box is used for sending the messages generated according to normal logics to a CAN bus; if a plurality of the CAN controllers sendthe messages to the CAN bus at the same time, small message identifiers obtain bus data and finish sending, and large message identifiers exit from arbitration; and the CAN controllers failing to obtain the bus reload the data to the second mail boxes of the CAN controllers and then send the data to the CAN bus when the bus is free. A retransmission time limiting mechanism is used for preventing the data from being retransmitting unlimitedly. The multi-device CAN communication intelligent retransmission method is easy to implement and capable of guaranteeing the operation safety performance of a control system.

Description

technical field [0001] The invention relates to a multi-device CAN communication intelligent retransmission method. Background technique [0002] In practical applications, the data of CAN communication is basically real-time data. When multiple CAN communication devices are connected, because the CAN communication mechanism uses the producer and consumer [the consumer mode is the communication mode, in this mode you can Receive data] mode, each device can be a producer or a consumer, so there will be a bus arbitration problem when communicating with each other. When the CAN module sends data, it will also monitor the bus at the same time. When the actual situation When arbitration occurs, the system will automatically trigger the arbitration mechanism of the CAN bus for arbitration processing. [0003] Suppose two nodes send data at the same time, the first 5 bits sent by node A are 10000, and the first 5 bits sent by node B are 10001. When the first 4 bits are sent, both ...

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Problems solved by technology

[0003] Suppose two nodes send data at the same time, the first 5 bits sent by node A are 10000, and the first 5 bits sent by node B are 10001. When the first 4 bits are sent, both nodes will think that they have sent successfully [because the first 4 bits are the same, so No error is reported, that is, the transmission is considered successful], but when the fifth bit is sent, the B node will lose the arbitration, because the priority of 0 is higher than the priority of 1, and the B node monitors that the bus is not 1, so it loses Arbitration, waiting to resend data

For CAN communication, assuming an arbitration error will also indicate that the transmission is complete, but in fact the data is not sent successfully, resulting in the failure of the current bus competition and abandoning the current transmission status, which in turn affects the error and failure of the communication system

[0004] At present, the arbitration error in CAN communication uses the wrong hardware retransmission method to solve the arbitration error problem, but there are unsafe factors. When the transmission is unsuccessful, it will continue to send until the transmission is successful.

In the process of CAN trying to send data, the mailbox is not updated (CAN communication uses the mailbox to send or receive data, the sent data and the received data are placed in the mailbox, once the bus is free, the data will be sent directly without the participation of the CPU) , which often leads to outdated data and misleads consumers, and is prone to misuse

[0005] Existing hardware retransmission mechanisms, such as figure 1 As shown, because the real-time update of data is not considered, the data that has not been successfully sent has been retransmitted. Once the retransmitted data that loses real-time performance is successfully sent, it is easy to cause signal logic confusion, and in severe cases, it will cause equipment failure and damage to personnel. casualties, therefore, it is necessary to improve the existing retransmission mechanism

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