A method for time synchronization between CAN bus multi-master communication
A CAN bus, time synchronization technology, applied in the direction of bus network, multiplexing communication, time division multiplexing system, etc., can solve the problems of synchronization master node unable to send data, bus occupancy, system deviation, etc., to achieve economical savings The effect of cost, good compatibility, good timing accuracy
Active Publication Date: 2021-03-26
NANJING SCIYON AUTOMATION GRP
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Problems solved by technology
First of all, the system needs to use a dedicated time communication bus for sending time messages, that is, an additional physical bus carrier is required, and each functional module needs to prepare a corresponding MAC layer and link layer chip, which will inevitably cause Waste; Secondly, for different communication rates, it is necessary to recalculate the compensation time deviation, and the calculation of this deviation time is only a theoretical calculation, with certain errors
[0005] In view of the above limitation 1, it is easy to think of unifying the transmission of time messages on the data communication bus, but since the data communication bus is a multi-master structure, that is, any node on the bus can send the time message after obtaining the right to use the bus. data, then it is very likely that when the time synchronization period of the synchronization master node arrives, when the time synchronization message is assembled and ready to be sent to the bus, the bus is already occupied by other nodes, and the synchronization master node cannot send data, and at this time, the bus It is uncertain when it will be occupied and when it can be released, so it is impossible to calculate this deviation in advance and realize accurate compensation, resulting in a deviation in system time synchronization, and at the same time, there are the above limitations 2
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[0025] The present invention will be further described below in conjunction with the accompanying drawings.
[0026] The present invention is applied to a method for time synchronization between CAN bus multi-master communication, such as figure 1 , as shown in the schematic diagram of CAN bus multi-master device communication architecture, there are multiple node devices on a bus, and each device can send data when it obtains the bus, that is, there are multiple master devices on the bus, and node 1 is set to have The right to send messages, that is, node 1 is the synchronization master node.
[0027] like figure 2 , when the time synchronization period of node 1 arrives, node 1 starts to read the time reference value to form a time synchronization message, and the accurate time reference value at this moment is T B , the time when node 1 completes sending the time synchronization message is T R ,Δt = T R -T B .
[0028] like image 3 , first of all, it is clear that...
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The invention discloses a method for time synchronization between CAN bus multi-master communication, the method does not need an additional time communication bus, and unifies the transmission of time synchronization messages and the transmission of data messages on one physical bus , the bus is still a multi-master architecture, and can dynamically calculate the transmission compensation time deviation according to the real-time performance of each transmission, and compensate in real time, saving the waste caused by an additional bus, effectively reducing costs, and eliminating the dependence on communication speed. It is flexible and real-time.
Description
Technical field: [0001] The invention belongs to the field of time synchronization of communication equipment, and relates to a method for time synchronization between CAN bus multi-master equipment communications. Background technique: [0002] In order to meet the needs of industrial production, general industrial production process control systems, such as DCS and PLC, are often composed of a series of modules with different functions. These functional modules work together to meet complex control logic. Since these functional modules are relatively independent, if each module maintains its own time, the time of the entire control system will be messy. Especially in some important industrial control fields such as power system control, including the event sequence recording system function, it is required that in the process of system joint debugging or production operation, once abnormal accidents such as shutdown and shutdown occur, the control system needs to be able t...
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IPC IPC(8): H04L12/40H04J3/06
CPCH04J3/0638H04J3/0682H04L12/40006H04L2012/40215
Inventor 陈闯张继淮陈刚峰芮正新
Owner NANJING SCIYON AUTOMATION GRP