Time synchronization method of master-slave structure multi-node network

Abstract

The invention discloses a time synchronization method of a master-slave structure multi-node network. Two clock synchronization mechanisms of a response type mechanism and a broadcast type mechanism are designed aiming at the condition that nodes of the network are physically connected through wires, and the communication between the nodes is performed through RS485, RS422, RS232, CAN bus modes. Accurate sending and receiving times of each message can be obtained through FPGA clock sampling. The transmission average delay and the master-slave clock offset are calculated through a response type synchronization mode, and the time precision is compensated and the time synchronization with the nanosecond grade high precision is reached. The time synchronization with the higher precision can be reached when the channel transmission time delay is ignored through a broadcast type synchronization mode.

Description

technical field [0001] The invention belongs to the technical field of network time synchronization of a centralized or distributed system, and in particular relates to a time synchronization method of a master-slave structure multi-node network. Background technique [0002] With the wide application of network systems, multi-nodes often require cooperative work, and the accuracy of system time / clock synchronization is getting higher and higher. A network-based system is a very complex and difficult task. Each node cooperates with each other to complete the task, and most of them rely on time for collaborative work. Therefore, the time / clock synchronization of each node in the network is one of the core technologies for data scheduling and tasks in a network-based real-time control system. It provides a mechanism to determine the sequence of events to ensure that nodes send and receive messages, Control, accident records, etc. ensure maximum consistency in time logic. All ...

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Problems solved by technology

[0004] At present, the protocols used for network clock synchronization mainly include: (1) GPS-based clock synchronization. GPS clock synchronization equipment is mainly developed through high-precision GPS positioning and timing modules. It has the advantage of high precision, but the application cost is high. And the device needs to work in an area that can receive GPS satellite signals

(2) Clock synchronization based on NTP (Network Time Protocol) protocol, which is based on client / server mode clock synchronization, mainly used to make the computer synchronize its server or clock source (such as atomic clock, GPS satellite and other international standard time) However, its clock synchronization accuracy can only reach the millisecond level on LAN (Local Area Network), and even reach milliseconds in time on WLAN (Wireless Local Area Network), and NTP is not suitable for use in the field of distributed measurement and control

The PTP clock synchronization protocol is used for the synchronization between the slave node clock and the master node clock in the network. It is suitable for the clock synchronization of one or more slave nodes. Because the PTP clock synchronization protocol can use hardware to analyze the message packet, and The mechanism of the secondary synchronization message packet is adopted, so compared with the NTP protocol, the clock synchronization accuracy of the PTP protocol is higher, but PTP belongs to the upper layer protocol mechanism, and does not involve the extraction mechanism of the underlying timestamp and the transmission mode between nodes.

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