CN103490966A - Dual-redundancy CAN bus data receiving and processing method - Google Patents

Abstract

In order to solve the problem that the prior art cannot simply and effectively process duplicate data received by two channels, the present invention provides a dual redundant CAN bus data receiving and processing method, including the following steps: (1) on the dual redundant CAN bus Simultaneously send the data composed of data frames on the first channel and the second channel of the dual redundant CAN bus; (2) receive the data of the first channel of the dual redundant CAN bus, and receive the data of the second channel of the dual redundant CAN bus at the same time; (3) Judging whether it is necessary to distinguish duplicate data in the data frames of the data received in the two channels; (4) directly use the data in the data frames that do not need to distinguish duplicate data, and distinguish the data frames that need to distinguish duplicate data: Yes The non-duplicate data in the data frame that has been differentiated is used, and the duplicate data in it is discarded. The invention uses a simple method to avoid the influence of software delay, line delay and the like on the data reception of the dual redundant CAN bus.

Description

A dual redundant CAN bus data receiving and processing method

technical field

The present invention relates to a data processing method, more specifically, to a dual redundant CAN bus data receiving and processing method.

Background technique

Using the traditional single CAN bus control network, there will be some failure links, such as main line failure, branch line failure, drive circuit failure and so on. Therefore, in the prior art, in order to improve the stability and security of data transmission, a dual redundant CAN bus network is usually used.

The method for ensuring communication reliability and error control in the prior art, such as a Chinese patent application (application number CN200810106342.6), discloses a communication method for a dual redundant CAN bus communication system, including the following steps: 1) in Start node 1 and node 2 in the network; 2) Establish a communication registration table between node 1 and node 2; 3) When node 1 wants to send a message to node 2, node 1 determines the transmission of the message according to the operation to be performed The mode is single-frame message transmission mode or large-scale message transmission mode; 4) If single-frame message transmission mode is adopted, the return N automatic retransmission mechanism is used to manage errors in the transmission process between two nodes; 5) If large-scale message transmission mode is adopted In the batch message transmission mode, the two nodes adopt the automatic retransmission mechanism of selection rejection to manage the error in the transmission process. The selection rejection automatic retransmission mechanism in the step 5 is that the receiving node requires the sending node to retransmit only frames with detected errors. However, the above method is not suitable for reliable communication when dual redundant channel hot switching technology and dual redundant channel data simultaneous sending and receiving technology are used.

Among them, the dual redundant channel hot switching technology is that one channel of the dual CAN bus is used as the working channel, and the other channel is hot backup. When the working channel fails, it is switched to the backup channel, and the backup channel continues to work as the working channel. If the original channel If it is repaired, it will be used as a backup channel. If it cannot be repaired, it will be identified as a fault.

The dual redundant channel data transmission and reception technology is that the two channels of the dual CAN bus are used as the working channel, and the data is transmitted on the two channels at the same time. As long as there is a channel with smooth data transmission, it is considered to be working normally.

However, in the prior art, there is no technical solution to simply and effectively solve the processing when duplicate data is received by two channels. The receiving nodes of the dual-redundant CAN bus system will receive the same data on the dual bus, and affected by software delays, line delays, etc., the interval time between the data received on the two channels will be different, how to distinguish between the received The received data is the key to receive processing as duplicate data.

Contents of the invention

In order to solve the above-mentioned problems in the prior art, the present invention provides a dual redundant CAN bus data receiving and processing method, which is proposed for the dual redundant channel data simultaneous transmission and reception technology.

According to one aspect of the present invention, a kind of dual redundant CAN bus data receiving and processing method is provided, comprising the steps:

(1) Simultaneously send data composed of data frames on the first channel and the second channel of the dual redundant CAN bus;

(2) Receive the data of the first channel of the dual redundant CAN bus, and simultaneously receive the data of the second channel of the dual redundant CAN bus;

(3) Determine whether duplicate data needs to be distinguished in the data frames of the data received in the two channels;

(4) Use directly the data in the data frame that does not need to distinguish duplicate data, and distinguish the data frame that needs to distinguish duplicate data: use the non-duplicate data in the data frame that has been differentiated, and use the duplicate data in it throw away.

In step (1), the message sequence number is stored in the data frame, and in each channel, the message sequence number of each data frame changes after each transmission.

Further, in step (3), it is determined whether it is necessary to distinguish repeated data according to the message identifier of the data frame.

Further, in step (4), distinction is made according to the message sequence number.

Further, step (4) includes the following steps:

(a) Obtain the message sequence number of the new data frame and the last message sequence number, where the message sequence number of the new data frame is the message sequence number of the current data frame received from one of the channels, and the last message sequence number is the The message sequence number of the data frame received through any channel before the current data frame and having the same message identifier of the data frame as the current data frame;

(b) Judging whether the message sequence number of the new data frame is equal to the last message sequence number: if they are equal, discard the received current data frame; otherwise, assign the message sequence number of the received current data frame to the last message sequence number message sequence number and use the current data frame.

Furthermore, the message sequence numbers of the same data sent on the two channels are the same, and the message sequence numbers of different data sent are different for each frame.

Furthermore, the message sequence number occupies a byte length and changes cyclically within the data range of 0-255.

The advantageous effect of the present invention is as follows: adopt this kind of double redundant CAN bus data receiving and processing method, only increase the transmission information of one byte, just can solve the processing problem of repeated instruction, also avoided software delay, circuit delay etc. Effect of redundant CAN bus data reception.

Description of drawings

Fig. 1 is a schematic diagram of a dual redundant CAN bus network structure according to an embodiment of the present invention;

Fig. 2 is the CAN interface expansion schematic diagram according to an embodiment of the present invention;

FIG. 3 shows a data frame format that needs to distinguish repeated data according to an embodiment of the present invention;

Fig. 4 shows a flow chart of data receiving processing according to an embodiment of the present invention.

Detailed ways

Specific embodiments of the present invention will be described below in conjunction with the accompanying drawings.

As shown in Figure 1-2, it is a schematic diagram of the structure of the dual redundant CAN bus network and a schematic diagram of CAN interface expansion.

In hardware, the dual redundant CAN bus uses two CAN buses, two CAN bus drivers, two CAN bus controllers and one CPU at the same time. CPU controls two CAN controllers simultaneously through different ports and interrupts. In one embodiment, the dual redundant CAN buses BUS A and BUS B require the use of the same two sets of CAN devices, thereby realizing physical media. The CAN device of BUS A includes an independent bus cable, bus driver 1-2 and bus controller 1-1, and the CAN device of BUS B includes an independent bus cable, bus driver 2-2 and bus controller 2-1. CPU1 is realized by FPGA.

During work, the same group of data can be sent through two buses BUS A and BUS B when sending. When receiving, the CPU controllers 1-1 and 2-1 can simultaneously process the data sent from the two buses BUS A and BUS B, receive and process them appropriately.

In one embodiment, the dual redundant CAN interface cards 1-1 and 1-2 are SJA1000 respectively, and they provide two independent CAN interfaces, 8-bit address/data bus and read-write control signals of each chip. The output signal of SJAl000 is connected to CAN transceiver PCA82C250 through optocoupler, and the power supply of PCA82C250 is an isolated power supply, which is provided by an isolated power conversion module. The reset signal of the CAN bus is provided by the FPGA chip, and the interrupt signal of the CAN controller SJAl000 is output to the FPGA.

In terms of software design, the VxWorks operating system is used to develop the driver. The VxWorks operating system is a high-performance, scalable embedded strong real-time operating system launched by Wind River Corporation (Wind RiverSyStem), which includes process management, storage management, device management, file system management, and network protocols. Several parts, such as system application and system application, only occupy a small storage space, and can be highly cut to ensure that the system can run with higher efficiency. With its good reliability and excellent real-time performance, it is widely used in communication, military, aviation, aerospace and other high-tech and high-real-time demanding fields.

The VxWorks operating system provides several standard driver models, such as serial device drivers, block device drivers, network interface drivers, and bus controller drivers. Depending on the equipment, you can choose the corresponding standard driver model or self-defined CAN module is a serial device, the design selects the standard serial device driver model.

As shown in FIG. 2 , according to an embodiment of the present invention, the data to be sent is simultaneously sent by CAN channel A and CAN channel B in the form of data frames, and the data sent on the above two channels are received simultaneously. In the data frames to be sent, frame message identifiers and message sequence numbers are stored.

In each channel, after each data frame is sent, the message sequence number of the data frame to be sent in the next frame will change from the frame sequence number of the data frame sent by this channel last time. In a preferred embodiment, the message sequence number occupies one byte, and will increase cyclically within the range of 0-255. As shown in FIG. 3, the message sequence number is placed in the data field of the frame data.

FIG. 3 also shows the frame format of each frame of data to be sent. Each frame of data includes: frame header (1 byte), arbitration field (1 byte), control field (1 byte), data field (8 bytes), frame tail and others (1 byte) part. Among them, the data field includes 8 bytes DAT A0-DAT A7, and DAT A0 is used to store the message sequence number.

The dual redundant CAN bus data receiving and processing method of the present invention will be described in detail below in conjunction with FIG. 4 .

According to a preferred embodiment of the present invention, the message sequence numbers of the same data sent on the two CAN channels A and CAN channel B are the same, and the message sequence numbers of different data sent are different for each frame. The message sequence number changes cyclically within the data range of 0-255, and the changing condition is: for different messages, the message sequence number changes. In a preferred embodiment, the message sequence number is incremented by 1 for different messages.

When the data composed of data frames is sent on CAN channel A and CAN channel B respectively, the data receiving end of the dual redundant CAN bus simultaneously receives the data composed of data frames sent by the two channels, and its reception is received frame by frame Achieved. Among them, the data receiving end of the dual redundant CAN bus uses various data receiving modules of the dual redundant CAN bus in the prior art, and its specific implementation is common knowledge of those skilled in the art, and is not an inventive point of the present invention. In some embodiments, Intel's 8XC196CA/CB, Philips' TJA1040, 82C250, LPC2292, Siemens' 81C90/91, etc. may be used.

After receiving two data frames from CAN channel A and CAN channel B respectively, it is necessary to judge whether it is necessary to distinguish repeated data in the two data frames. The so-called repeated data is defined as two data frames that have the same frame message identifier and belong to different CAN channels. Therefore, when judging, it is determined whether it is necessary to distinguish repeated data according to the message identifier of the data frame. Among them, the data in the data frame that does not need to distinguish repeated data can be used directly; and the data frame that needs to distinguish repeated data is distinguished.

The specific operation of the above distinction is: according to the message sequence number, the above data frames belonging to different channels are distinguished. In a preferred embodiment, this distinction includes the following two steps:

(a) Obtain the message sequence number of the new data frame and the last message sequence number, where the message sequence number of the new data frame is the message sequence number of the current data frame received from one of the channels, and the last message sequence number is the The message sequence number of the data frame received through any channel before the current data frame and having the same frame message identifier as the current data frame;

(b) Judging whether the message sequence number of the new data frame is equal to the last message sequence number: if they are equal, discard the received current data frame; otherwise, assign the message sequence number of the received current data frame to the last message sequence number message sequence number and use the current data frame.

By analogy, multiple data frames received constitute the original data when sending.

Each of the above embodiments is only a description of the preferred implementation of the present invention, and is not intended to limit the scope of the present invention. All such modifications and improvements should fall within the scope of protection defined by the claims of the present invention.

Claims (7)

1. a double redundant CAN bus data receiving and processing method, is characterized in that, comprises the steps: (1) Simultaneously send data composed of data frames on the first channel and the second channel of the dual redundant CAN bus; (2) Receive the data of the first channel of the dual redundant CAN bus, and simultaneously receive the data of the second channel of the dual redundant CAN bus; (3) Determine whether duplicate data needs to be distinguished in the data frames of the data received in the two channels; (4) Use directly the data in the data frame that does not need to distinguish duplicate data, and distinguish the data frame that needs to distinguish duplicate data: use the non-duplicate data in the data frame that has been differentiated, and use the duplicate data in it throw away. 2. The data receiving and processing method according to claim 1, characterized in that, in step (1), the message serial number is stored in the data frame, and in each channel, the message serial number of each data frame is sent every time Changes occur later. 3 . The data receiving and processing method according to claim 2 , wherein in step (3), it is determined whether it is necessary to distinguish duplicate data according to the message identifier of the data frame. 4 . 4. The data receiving and processing method according to claim 3, characterized in that in step (4), according to the message serial number to distinguish. 5. The data receiving and processing method according to claim 4, characterized in that step (4) further comprises the following steps: (a) Obtain the message sequence number of the new data frame and the last message sequence number, where the message sequence number of the new data frame is the message sequence number of the current data frame received from one of the channels, and the last message sequence number is the A message sequence number of a data frame having the same frame message identifier as the current data frame received through any channel before the current data frame; (b) Judging whether the message sequence number of the new data frame is equal to the last message sequence number: if they are equal, discard the received current data frame; otherwise, assign the message sequence number of the received current data frame to the last message sequence number message sequence number and use the current data frame. 6. The data receiving and processing method according to claim 3, wherein the message sequence numbers of the same data sent on the two channels are the same, and the message sequence numbers of different data sent are different for each frame. 7. The data receiving and processing method according to claim 6, wherein the message sequence number occupies one byte length and changes cyclically within the data range of 0-255.

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