CN100417122C - A Scheduling Method for Realizing Ethernet Deterministic Communication - Google Patents

Abstract

The invention discloses a method for realizing Ethernet deterministic communication scheduling. By adding a deterministic communication scheduling management entity on the data link layer of Ethernet for each device, the relationship between the data link layer and the data link layer users is established. It is used to control the sending of all periodic data packets and non-periodic data packets of the device. The roles of all network devices in the present invention are equal, thereby embodying the fairness principle of Ethernet communication, and avoiding the use of token-based centralized scheduling in the stage of transmitting aperiodic data messages, without transmitting a large number of tokens on the channel. card, which not only improves the efficiency of aperiodic data transmission, but also improves the utilization rate of the entire Ethernet bandwidth; in the periodic data message sending stage of the present invention, the same device can send periodic data according to the size and number of periodic data sent by itself, in the same communication Multiple periods for sending periodic data packets are set in the macrocycle, thereby providing a more flexible scheduling method.

Description

A Scheduling Method for Realizing Ethernet Deterministic Communication

technical field

The present invention relates to the field of Ethernet communication, in particular to a scheduling method for deterministic communication between a plurality of network nodes in an industrial control network based on Ethernet+UDP (User Datagram Protocol)/IP.

Background technique

As a mature network technology, Ethernet has many advantages such as low cost, stability and reliability, etc. It has been widely used in the field of office automation and industrial control, and has become one of the most popular communication networks. The currently used Ethernet standards mostly use the CSMA/CD (Carrier Sense Multiple Access/Collision Detect) protocol with collision detection at the MAC (Media Access Control) layer. When a certain node needs to send data, it first monitors the channel, and if the channel is busy, it will continue to wait until it detects that the channel is free, and then sends the data. If two or more nodes are listening and waiting to send data, when the channel is detected to be idle, each node immediately (almost at the same time) starts sending data, and a conflict occurs at this time. If a node detects a collision during transmission, it immediately stops transmission and sends a "congestion" signal to the channel to ensure that all other nodes on the network also see the collision. In an Ethernet-based communication system, in order to avoid conflicts, each node adopts Binary Exponential Back-Off (BEB, Binary Exponential Back-Off) algorithm to deal with conflicts, but this method has the defect of uncertain conflict delay and cannot be used in industrial control networks It can be effectively applied in real-time network.

The industrial control network is a typical real-time application system, in which the tasks (such as the execution of function blocks) are usually triggered according to a certain time interval, and there is a deadline requirement for the execution time of the tasks. This task is called a periodic task. There is also a task in the real-time application system, which only occurs when a specific event is triggered, such as device configuration, fault diagnosis, program upload/download, running record, alarm processing, etc. Such tasks are called aperiodic Tasks, non-periodic tasks are triggered randomly. These two tasks are reflected in the communication of the industrial control network, which are two types of communication information: periodic communication information and non-periodic communication information. Periodic information is real-time information, non-periodic information is non-real-time information, and periodic communication information and non-periodic communication information have different time characteristics. Also, aperiodic information usually has a higher priority. Once the system configuration is complete, the periodic communication messages are sent with time determinism. Non-periodic communication information is often burst information, which is uncertain in time.

In order to improve the real-time and deterministic nature of Ethernet communication, the applicant submitted to the State Intellectual Property Office a patent application titled "A Scheduling Method for Realizing Ethernet Deterministic Communication" (application number 03142040.0). The technical solution includes the following steps:

First, define at least one master device and several slave devices on the Ethernet, and also set up a clock server for clock synchronization;

Then, the information in the Ethernet is divided into periodic information and non-periodic information, the control method of time slot access is adopted for periodic information, and periodic data exchange is performed in a fixed time slice; token-based information is used for non-periodic information Centralized scheduling mode, data exchange is carried out in the interval of periodic information communication, that is, in the period of non-periodic information communication.

Although the above method can reasonably schedule the periodic and non-periodic information in the industrial control network, and then realize the real-time and deterministic communication of the industrial control network, it still has the following problems:

First: Setting up a master device in the existing network destroys the fairness principle of Ethernet communication, especially the token-based centralized scheduling method adopted when transmitting aperiodic data, which makes it necessary to transmit a large number of Tokens not only increase the time of aperiodic data transmission, but also reduce the utilization rate of the entire Ethernet bandwidth;

Second: In the same cycle, each device can only send cycle data once, which brings inconvenience to the device to transmit data.

Contents of the invention

The purpose of the present invention is to provide a scheduling method for realizing Ethernet deterministic communication, so as to solve the problem of setting up a master device in the network in the prior art, destroying the fairness principle of Ethernet communication and adopting a method based on The centralized scheduling method of tokens increases the transmission time and reduces the technical problems of bandwidth utilization.

In order to solve the above problems, the present invention discloses a scheduling method for realizing deterministic communication of Ethernet. The Ethernet includes several devices and a clock server for clock synchronization between the devices. The information in the Ethernet is divided into Periodic data and aperiodic data, all devices on the Ethernet communicate in a preset communication macrocycle, and each communication macrocycle is divided into a periodic data message transmission phase and an aperiodic data message transmission phase,

(1) Add a deterministic communication scheduling management entity on the data link layer of the Ethernet for each device, which establishes a connection between the data link layer and the data link layer user, and is used for all periodic data of the device Control the sending time of messages and aperiodic data messages;

(2) Before the system is started, a configuration step is performed, at least including: each device sets and saves the deviation of the start time of the device transmitting periodic data messages in the communication macrocycle relative to the start time of the communication macrocycle Amount Tn, setting and saving the deviation of the aperiodic data message transmission phase relative to the initial moment of the communication macrocycle;

(3) all devices periodically synchronize with the clock server clock;

(4) In the period data packet transmission stage of each communication macrocycle, whenever the device detects that the system has reached the moment when the device sends periodic data packets, if there is periodic data to be sent, it will first send the periodic data; Periodic data message declaration message, on the contrary, directly send aperiodic data message declaration message, the aperiodic data message declaration message includes whether aperiodic data message needs to be sent, and the priority of the sent aperiodic data message level, the IP address of the sending device, and the required sending completion time;

(5) All devices save the received aperiodic data message declaration message in the aperiodic data message sending management list pre-established by the deterministic communication scheduling management entity of the device, and according to the priority of the message and the sender The IP address of the device is queued;

(6) In the aperiodic data transmission phase of each communication macrocycle, whenever the system reaches the time when the aperiodic data message is sent or when the device receives the aperiodic data message sending end declaration message sent by the previous device, And when the remaining time in this communication macro cycle can send the aperiodic data message of the device, the device sends the aperiodic data message, and sends the aperiodic data message to other devices after sending the end statement message, The preceding device is a device that sends the aperiodic data message earlier than the aperiodic data message of the current device in the aperiodic data message sending management list.

In step (4), the device detects whether the system has reached the time when the device sends periodic data packets by judging whether T1 MOD T2 = Tn is established, wherein T1 is the current time of the device, and T2 is the time period of the communication macro cycle.

In the data transmission phase of the same cycle, a device can set one or more Tn.

The deterministic communication scheduling management entity sets the standby state, the ready state, the periodic data transmission state and the non-periodic data transmission state, wherein, after the system is configured, the deterministic communication scheduling management entity changes from the standby state to the ready state state, when the time for the device to send the periodic data message arrives, the state of the deterministic communication scheduling management entity changes to the periodic data sending state, and after the periodic data message is sent, the deterministic communication scheduling management entity sends Aperiodic data message declaration message, and change the deterministic communication scheduling management entity to the ready state, if it is necessary to send the aperiodic data message of the device, then the state of the deterministic communication scheduling management entity is changed to aperiodic In the data sending state, after the device sends the aperiodic data message, the deterministic communication scheduling management entity returns to the ready state.

Queuing according to priority and IP address in step (5) specifically includes:

Aperiodic data packets are sorted according to the priority from high to low. When the priorities are the same, they are sorted according to the preset settings: if the preset IP address is sent first, the priority is the same and the IP address is the first. Conversely, if it is preset that the one with the lower IP address is sent first, the priority will be the same and the one with the lower IP address will be sent first.

Wherein, step (6) specifically includes:

(6-1) In the aperiodic data transmission stage of each communication macrocycle, each device judges whether the device has aperiodic data message transmission, if so, proceed to step (6-2), otherwise, determine the The status of the sexual communication scheduling management entity is set to the ready state;

(6-2) The deterministic communication scheduling management entity judges whether the priority of the aperiodic data message of the device is the highest, if so, wait until the sending time of the aperiodic data message, and then perform step (6-4), Otherwise, proceed to step (6-3);

(6-3) The deterministic communication scheduling management entity judges whether the aperiodic data message sending end statement message sent by the previous device has been received, if so, proceed to step (6-4), otherwise proceed to step (6- 2), the previous device is a device that sends an aperiodic data message earlier than the aperiodic data message of this device in the aperiodic data message sending management list;

(6-4) Determine whether the remaining time in the communication macrocycle can send the aperiodic data message of this device, if so, send the aperiodic data message, and then send the aperiodic data message to other devices to send the end statement , otherwise set the state of the deterministic communication scheduling management entity to the ready state.

Wherein, the clock synchronization in the step (3) includes implementing simple network time protocol SNTP or IEEE1588 precise time synchronization protocol between each device and the clock server.

If it is detected that a device does not send an aperiodic data message declaration message within three communication macrocycles, the device is an invalid device.

Compared with the prior art, the present invention has the following advantages:

First: The roles of all network devices are equal, and there is no distinction between master and slave devices, thus reflecting the fairness principle of Ethernet communication, and avoiding token-based centralized scheduling during the transmission of aperiodic data packets , there is no need to transmit a large number of tokens on the channel, which not only improves the efficiency of aperiodic data transmission, but also improves the utilization rate of the entire Ethernet bandwidth;

Second: in the periodic data message sending stage of the present invention, the same device can set a plurality of periods for sending periodic data messages in the same communication macrocycle according to the size and number of its own sending periodic data messages, thereby providing a more Flexible scheduling method.

Description of drawings

Fig. 1 is the data link layer model of scheduling method of the present invention;

Fig. 2 is an example conversion diagram of the deterministic communication scheduling management entity state used in the scheduling method of the present invention;

3 is a schematic diagram of the division of the communication macrocycle of the network transmission time of the scheduling method of the present invention;

Fig. 4 is a schematic diagram of an information communication process in a transmission communication macrocycle of a six-device communication instance of the scheduling method of the present invention;

Fig. 5 is the schematic diagram that realizes clock synchronization according to SNTP in the scheduling method implementation of the present invention;

Fig. 6 is a flow chart of the sending process of periodic data message;

FIG. 7 is a flow chart of the aperiodic data packet sending process of the scheduling method of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings.

The invention discloses a scheduling method for realizing Ethernet deterministic communication, which is used to control the time of sending messages of each device in the Ethernet, so as to ensure that only one device sends messages to the network at the same time, and then reaches the industrial control network The purpose of real-time and deterministic communication in .

In the present invention, besides the device (or node) that sends the message, the Ethernet also includes a clock server for clock synchronization between devices. The information in the Ethernet is divided into periodic data and aperiodic data. Similarly, the messages to be sent by each device also include periodic data messages and aperiodic data messages. As the name implies, a cyclic data telegram contains cyclic data and an acyclic data telegram contains acyclic data.

The entire network transmission time is divided into an infinite number of equal-length communication macrocycles, each of which includes a periodical data packet transmission phase and an aperiodic data packet transmission phase, and all devices send and receive messages in each communication macrocycle Receive cyclic data telegrams and acyclic data telegrams.

Please refer to Fig. 1, it is the used data link layer model of the dispatching method of the present invention, that is, the deterministic communication scheduling management entity is set in the data link layer of Ethernet, and it is set in the logical link control layer , to establish a connection between the logical link control layer and the data link layer user, which is mainly used to control the sending time of all periodic data and aperiodic data packets of this device, so as to ensure that only one device sends to the network at the same time packets, thereby completely avoiding packet collisions. All devices on the Ethernet network of the present invention are not divided into master devices and slave devices, that is, the roles of all devices are equal, so the scheduling on the Ethernet network is realized by the deterministic communication scheduling management entity of each device .

In order to realize real-time and deterministic communication more conveniently, the applicant proposes a control process embodiment of a deterministic communication scheduling management entity. Please refer to FIG. 2 , which is a state transition diagram of a deterministic communication scheduling management entity. Each deterministic communication scheduling management entity is described by four states and transitions between them. The four states are "Standby", "Ready", "Periodic Data Sending" and "NonPeriodic Data Sending".

Wherein, after the system is configured, the deterministic communication scheduling management entity changes from the standby state to the ready state. Change to the periodic data sending state. After sending the periodic data message, the deterministic communication scheduling management entity sends an aperiodic data message declaration message, and changes the deterministic communication scheduling management entity to the ready state. If necessary Send the aperiodic data message of the device, the state of the deterministic communication scheduling management entity changes to the aperiodic data sending state, after the aperiodic data message of the device is sent, the deterministic communication scheduling management entity returns to the preparation state.

During the message transmission process, the deterministic communication scheduling management entity controls the sending of all periodic data and aperiodic data messages of the device to ensure that at any time, only one device on the network sends messages, and in the communication macro cycle Among them, the message with higher priority is sent first. When the priority is the same, it is judged which message is sent first according to the IP address of the device, thus ensuring the certainty and real-time performance of Ethernet communication.

Before the system starts, configure the entire system first, including at least: the size of the device communication macrocycle; the time length for each device to send periodic data in a communication macrocycle; set the transmission cycle of each device in the communication macrocycle The offset of the starting moment of the data relative to the starting moment of the transmission communication macrocycle; and save this information in each device; each device sets and saves the transmission period data message of the device in the communication macrocycle The deviation of the starting time relative to the starting time of the communication macrocycle; and setting and saving the deviation of the aperiodic data packet transmission phase relative to the starting time of the communication macrocycle.

Please refer to FIG. 3 , which is a schematic diagram of division of communication macrocycles of network transmission time. In this figure, network transmission time is divided into infinite communication macrocycles of equal length. Each communication macrocycle consists of a periodic data message sending phase and an aperiodic data message sending phase.

Fig. 4 is a schematic diagram of an implementation of an information communication process in a communication macrocycle. In Fig. 4, there are 6 devices communicating in the example network. It can be seen from Figure 4 that the time for each device to send periodic data is determined during system configuration; the deviations of the start time of each device sending periodic data relative to the start time of the transmission cycle are different, so as to avoid It eliminates the possibility of conflicts when multiple devices access network resources at the same time. At the same time, each device sends periodic data with certainty in time, that is, once a device sends a periodic data at a certain moment, the next time the device sends the same periodic data can be calculated by the following method:

NextSendTime=CurrentTime+transmission period

Among them, NextSendTime is the time when the device transmits the data of the same period next time, and CurrentTime is the moment when the data of the current transmission period is transmitted.

In the present invention, the same device is allowed to send periodic data multiple times in one cycle, for example, two moments of sending periodic data are set in the same device, such as setting S1 and S2, and S1 is the communication macro cycle of this device The first deviation of the starting moment of the transmission period data message relative to the starting moment of the communication macrocycle, S2 is the starting moment of the transmission period data message of the device in the communication macrocycle relative to the beginning of the communication macrocycle The second offset of the moment. Therefore, the above-mentioned device can detect the sending time of sending the periodic data message of the device twice in the same cycle.

In the present invention, it is also possible to detect whether the system arrives at the time when the device sends periodic data messages by judging whether T1 MOD T2=Tn is established, wherein T1 is the current time of the device, T2 is the time period of the communication macrocycle, and Tn It is the deviation of the starting moment of the periodic data message transmission of the device in the communication macrocycle relative to the starting moment of the communication macrocycle. Similarly, a device can set one or more Tn in the same period of data transmission. , the Tn is the deviation from the start time of the device transmitting periodic data packets in the communication macrocycle relative to the start time of the communication macrocycle.

Since the scheduling method of the Ethernet deterministic communication is similar in each communication macrocycle, the scheduling method of the Ethernet deterministic communication of the present invention will be described in detail below by taking one communication macrocycle as an example.

The scheduling method of the Ethernet deterministic communication in a communication macrocycle mainly includes three processes: the process of establishing clock synchronization between each device and the clock server; the process of sending periodic data messages and the process of sending aperiodic data messages.

(1) Clock synchronization process

FIG. 5 is a schematic diagram of implementing clock synchronization with SNTP (Simple Network Time Protocol). Keeping the strict clock synchronization among the various devices in the present invention is realized through the UDP-based SNTP protocol, as shown in FIG. 5 . Using SNTP to achieve clock synchronization between devices is actually to allow each device to periodically exchange SNTP messages with the clock server to calculate the time difference between the device and the clock server, thereby adjusting the local clock so that the local clock of the device is consistent with the clock server The time difference between them is kept within the allowable range. Four timestamps are used when calculating the time difference between the device and the clock server: U ₁ , U ₂ , U ₃ and U ₄ , and their meanings are as follows:

U ₁ : the local time stamp when the device sends the clock synchronization request;

U ₂ : the time stamp (standard time) when the clock server receives the clock synchronization request;

U ₃ : the time stamp (standard time) when the clock server sends the clock synchronization response;

U ₄ : The local time stamp when the device receives the clock synchronization reply.

Simple Network Time Protocol implements clock synchronization based on an assumption that the transmission delay between the device to the clock server and the clock server to the field device is equal. Based on this assumption, we calculate the time deviation T _d between the field device and the clock server through the following algorithm.

U ₂ −(U ₁ +U _d )=(U ₄ +U _d )−U ₃

According to the above formula, the time deviation U _d between the device and the clock server can be calculated:

U _d =((U ₂ -U ₁ )+(U ₃ -U ₄ ))/2

The device can adjust the local clock according to the time deviation U _d , so as to achieve synchronization with the clock server. After all devices on the network are synchronized with the clock server in the same way, it means that all devices on the network are also synchronized in time.

(2) Periodic data sending process

Please refer to FIG. 6 , which is a schematic diagram of a periodic data sending process of a device in a communication macrocycle.

First, step S110 is performed. In the periodical message transmission phase of the communication macrocycle, if the deterministic communication scheduling management entity of each device detects the time when the device sends the periodic message, the deterministic communication scheduling management entity of the device is changed to In the state of "periodic data transmission", if the device has periodic messages, then send periodic messages, otherwise, directly proceed to step S120;

Then proceed to step S120: the deterministic communication scheduling management entity of the device judges whether there is other time to send periodic data in the current communication macrocycle, if so, proceed to step S110, otherwise proceed to step S130; the deterministic communication dispatching management entity detects Tn The number of periodic data packets that the device needs to send in the same communication macrocycle can be known, and Tn is the starting time of the device transmitting periodic data packets in the communication macrocycle relative to the start of the communication macrocycle The amount of deviation from the initial moment;

Then proceed to step S130: transmit the periodic aperiodic data message declaration message to the data link layer, and the data link layer sends the periodic data message declaration to each other device, and the deterministic communication scheduling management entity is changed to Ready state; the aperiodic data message declaration message includes whether there is aperiodic data to be sent, the IP address of the sender, the sending priority of the aperiodic data message, and the required sending time and other parameters.

Finally, step S140 is performed: each device stores the aperiodic data message declaration message in the pre-established aperiodic data message sending management list, and queues it according to priority and IP address. Aperiodic data packets are sorted according to the priority from high to low. When the priorities are the same, they are sorted according to the preset settings: if the preset IP address is sent first, the priority is the same and the IP address is the first. Conversely, if it is preset that the one with the lower IP address is sent first, the priority will be the same and the one with the lower IP address will be sent first, or

Aperiodic data packets are sorted according to priority from low to high. When the priority is the same, they are sorted according to the preset settings: if the preset IP address is sent first, the priority is the same and the IP address is ranked last. Conversely, if it is preset that the one with the lower IP address will be sent first, the priority will be the same and the one with the lower IP address will be ranked last.

In the present invention, the aperiodic data message transmission management list is still sorted from high to low in priority, and the one with the same priority and the higher IP address is sent first, that is, the one with the higher IP address in the same priority is sent in the aperiodic data message. top in the file sending management list.

In step S140, the deterministic communication scheduling management entity of the device receives an aperiodic data message sending declaration message, and inserts the aperiodic data message sending declaration message into the aperiodic data message sending management list. Certainly, in order to improve the efficiency, all the non-periodic data message sending declaration messages in the aperiodic data message sending management list may also be sorted together after the periodic data message sending ends.

(3) Aperiodic data message transmission

Please refer to Fig. 7, which is a sending process of a communication macrocycle device sending aperiodic data message in the present invention, including the following steps:

S210: In the aperiodic data transmission phase of each communication macrocycle, each device judges whether the device has aperiodic data message transmission, if so, proceed to step S220; otherwise, set the status of the deterministic communication scheduling management entity in a state of readiness;

S220: Determine whether the priority of the aperiodic data message of the device is the highest, if so, the deterministic communication scheduling management entity of the device waits until the sending time of the aperiodic data message, and then proceed to step S240, otherwise, proceed to step S230 ;

S230: The deterministic communication scheduling management entity judges whether it has received the aperiodic data message sending end declaration message sent by the previous device, if yes, go to step S240, otherwise go to step S220, the previous device is aperiodic A device that sends aperiodic data packets earlier than the aperiodic data packets of this device in the data packet sending management list;

S240: Determine whether the remaining time in this communication macrocycle can send the aperiodic data message of this device, if so, send the aperiodic data message, and then send the aperiodic data message sending end statement to other devices, otherwise it will The state of the deterministic communication scheduling management entity is set to the ready state.

Due to the adoption of the above technical solution, the present invention provides a scheduling method for deterministic communication at the user layer above UDP, to reasonably schedule periodic and non-periodic data in the industrial control network, using Ethernet+UDP/IP as the The real-time and deterministic communication is realized on the basic industrial control network to meet the real-time and deterministic requirements of the industrial control network based on the traditional Ethernet standard.

The above disclosures are only several specific embodiments of the present invention, but the present invention is not limited thereto, and any changes conceivable by those skilled in the art should fall within the protection scope of the present invention, and the protection scope of the present invention begins with The claims shall prevail.

Claims (8)

1. A scheduling method for realizing Ethernet deterministic communication, the Ethernet includes a number of devices and a clock server for clock synchronization between devices, the information in the Ethernet is divided into periodic data and non-periodic data, All devices on the Ethernet communicate in a preset communication macrocycle, and each communication macrocycle is divided into a periodic data message transmission phase and an aperiodic data message transmission phase, characterized in that, (1) Add a deterministic communication scheduling management entity on the data link layer of the Ethernet for each device, which establishes a connection between the data link layer and the data link layer user, and is used for all periodic data of the device Control the sending time of messages and aperiodic data messages; (2) Before the system is started, a configuration step is performed, at least including: each device sets and saves the deviation of the start time of the device transmitting periodic data messages in the communication macrocycle relative to the start time of the communication macrocycle Amount Tn, setting and saving the deviation of the aperiodic data message transmission phase relative to the initial moment of the communication macrocycle; (3) all devices periodically synchronize with the clock server clock; (4) In the period data packet transmission stage of each communication macrocycle, whenever the device detects that the system has reached the moment when the device sends periodic data packets, if there is periodic data to be sent, it will first send the periodic data; Periodic data message declaration message, on the contrary, directly send aperiodic data message declaration message, the aperiodic data message declaration message includes whether aperiodic data message needs to be sent, and the priority of the sent aperiodic data message level, the IP address of the sending device, and the required sending completion time; (5) All devices save the received aperiodic data message declaration message in the aperiodic data message sending management list pre-established by the deterministic communication scheduling management entity of the device, and according to the priority of the message and the sender The IP address of the device is queued; (6) In the aperiodic data transmission phase of each communication macrocycle, whenever the system reaches the time when the aperiodic data message is sent or when the device receives the aperiodic data message sending end declaration message sent by the previous device, And when the remaining time in this communication macro cycle can send the aperiodic data message of the device, the device sends the aperiodic data message, and sends the aperiodic data message to other devices after sending the end statement message, The preceding device is a device that sends the aperiodic data message earlier than the aperiodic data message of the current device in the aperiodic data message sending management list. 2. The scheduling method for realizing Ethernet deterministic communication as claimed in claim 1, wherein the equipment in step (4) detects whether the system arrives at the equipment to send periodic data by judging whether T1 MOD T2=Tn is set up Message time, where T1 is the current time of the device, and T2 is the time period of the communication macrocycle. 3. The scheduling method for realizing Ethernet deterministic communication as claimed in claim 1 or 2, wherein a device can set one or more Tn in the same cycle data transmission phase. 4. the scheduling method that realizes Ethernet deterministic communication as claimed in claim 1 or 2, it is characterized in that, described deterministic communication scheduling management entity sets standby state, ready state, periodic data sending state and aperiodic data sending state , wherein, after the system is configured, the deterministic communication scheduling management entity changes from the standby state to the ready state, and when the time for the device to send periodic data packets arrives, the deterministic communication scheduling management entity The state changes to the periodic data sending state. After sending the periodic data message, the deterministic communication scheduling management entity sends an aperiodic data message declaration message, and changes the deterministic communication scheduling management entity to the ready state. If If it is necessary to send the aperiodic data message of the device, the state of the deterministic communication scheduling management entity changes to the aperiodic data sending state. After the aperiodic data message of the device is sent, the deterministic communication scheduling management entity returns to the Ready state. 5. the scheduling method that realizes Ethernet deterministic communication as claimed in claim 1, it is characterized in that, in step (5), according to priority and IP address, queue up specifically comprises: Aperiodic data packets are sorted according to the priority from high to low. When the priorities are the same, they are sorted according to the preset settings: if the preset IP address is sent first, the priority is the same and the IP address is the first. Conversely, if it is preset that the one with the lower IP address is sent first, the priority will be the same and the one with the lower IP address will be sent first. 6. the scheduling method that realizes Ethernet deterministic communication as claimed in claim 4, is characterized in that, step (6) specifically comprises: (6-1) In the aperiodic data transmission stage of each communication macrocycle, each device judges whether the device has aperiodic data message transmission, if so, proceed to step (6-2), otherwise, determine the The status of the sexual communication scheduling management entity is set to the ready state; (6-2) The deterministic communication scheduling management entity judges whether the priority of the aperiodic data message of the device is the highest, if so, wait until the sending time of the aperiodic data message, and then perform step (6-4), Otherwise, proceed to step (6-3); (6-3) The deterministic communication scheduling management entity judges whether the aperiodic data message sending end statement message sent by the previous device has been received, if so, proceed to step (6-4), otherwise proceed to step (6- 2), the previous device is a device that sends an aperiodic data message earlier than the aperiodic data message of this device in the aperiodic data message sending management list; (6-4) Determine whether the remaining time in the communication macrocycle can send the aperiodic data message of this device, if so, send the aperiodic data message, and then send the aperiodic data message to other devices to send the end statement , otherwise set the state of the deterministic communication scheduling management entity to the ready state. 7. Ethernet deterministic communication scheduling method as claimed in claim 1, is characterized in that, in step (3), clock synchronization comprises simple network time protocol SNTP or IEEE1588 precise time by communication between each equipment and described clock server Synchronous protocol implementation. 8. The Ethernet deterministic communication scheduling method according to claim 1, wherein if it is detected that a device does not send an aperiodic data message declaration message within three communication macrocycles, the device is a failure device .

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