CN117478501A

CN117478501A - Method, control device and storage medium for configuration of EPA network

Info

Publication number: CN117478501A
Application number: CN202311791277.6A
Authority: CN
Inventors: 陈建飞; 苏梦鸻; 丁祎辰; 顾昊
Original assignee: Zhejiang Guoli Xin'an Technology Co ltd
Current assignee: Zhejiang Guoli Xin'an Technology Co ltd
Priority date: 2023-12-25
Filing date: 2023-12-25
Publication date: 2024-01-30
Anticipated expiration: 2043-12-25
Also published as: CN117478501B

Abstract

The invention provides a method, control equipment and computer readable storage medium for configuration of EPA network. The method comprises the following steps: acquiring the number of EPA nodes contained in the EPA network and the user data volume of each EPA node; determining configuration parameters of the EPA network based on the number of EPA nodes contained in the EPA network and the user data volume of each EPA node, wherein the configuration parameters comprise the macro period length, the period time period length and the transmission offset time of each EPA node in the macro period of the EPA network; and configuring the EPA network based on the configuration parameters.

Description

Method, control device and storage medium for configuration of EPA network

Technical Field

The present invention relates generally to the field of industrial control, and more particularly, to a method, control device and computer readable storage medium for configuration of an EPA network.

Background

In recent years, as the control system is rapidly converted into digital and intelligent, various automation systems and informatization systems are applied to the control system, so that the requirements of the control system on communication are higher and higher.

EPA (Ethernet for Plant Automation) factory automation Ethernet is a real-time Ethernet technology which is developed by China independently and faces a control system, and is already recorded by a field bus international standard IEC61158 and a real-time Ethernet standard IEC61784, so that EPA is widely applied to various fields of electric power, chemical industry, machinery, mining, petroleum and the like. In order to adapt to different application scenes in the EPA network, the connection between EPA equipment nodes has different network topologies. Correspondingly, under different network topologies, different node numbers and different control requirements, configuration parameters including macro periods, periods and the like in each EPA equipment node are different.

Therefore, in the prior art, the configuration of the EPA equipment in the EPA network can only be performed by manual mode, when a plurality of equipment nodes exist in the network, huge workload can be generated, and errors are easy to occur. The invention provides an automatic configuration scheme for the EPA network.

Disclosure of Invention

In view of the above, the present invention provides a method for automatically determining various configuration parameters of an EPA network to configure the EPA network.

According to one aspect of the present invention, a method for configuration of an EPA network is provided. The method comprises the following steps: acquiring the number of EPA nodes contained in the EPA network and the user data volume of each EPA node; determining configuration parameters of the EPA network based on the number of EPA nodes contained in the EPA network and the user data volume of each EPA node, wherein the configuration parameters at least comprise the length of a macro period, the length of a period time period of the EPA network and the transmission offset time of each EPA node in the macro period; and configuring the EPA network based on the configuration parameters.

In some implementations, determining configuration parameters of the EPA network includes: determining the period time period length based on the number of EPA nodes contained in the EPA network and the amount of user data for each EPA node; determining a macrocycle length of the EPA network based on the cycle time period length and the non-cycle time length; and for each EPA node in the EPA network, determining a transmission offset time for the EPA node based on a transmission offset time of a previous EPA node to the EPA node and a total time occupied by the previous EPA node.

In some implementations, determining the period time period length includes: for each EPA node, determining the message occupation time of the EPA node based on the user data volume of the EPA node; determining the period time slice length of the EPA node based on the message occupation time, the transmission shaping time and the message reservation time of the EPA node; and summing the period time slice lengths of all EPA nodes of the EPA network to determine the period time slice length of the EPA network.

In some implementations, determining the macrocycle length of the EPA network includes: determining the non-periodic time length based on a preset non-periodic reserved time slice and a clock synchronization error; and summing the period time period length and the non-period time length to determine a macrocycle length of the EPA network.

In some implementations, determining the transmission offset time of the EPA node includes: for a first EPA node in the EPA network, setting the transmission offset time of the first EPA node to 0; for each EPA node in the EPA network except for the first EPA node, determining a transmission shaping time for the EPA node based at least on an inter-node line delay, a node forwarding delay and a clock synchronization error for a node preceding the EPA node; determining the total time occupied by the previous EPA node based on the transmission shaping time of the EPA node, the message occupied time of the previous EPA node of the EPA node and the message reserved time; and determining a transmission offset time for the EPA node based on a transmission offset time for a previous EPA node of the EPA node and a total time occupied by the previous EPA node.

In some implementations, the topology of the EPA network includes a ring structure, a linear structure, or a star structure.

In some implementations, determining the transmission shaping time of the EPA node includes: and determining the transmission shaping time of the EPA node based on the inter-node line delay, the node forwarding delay, the clock synchronization error and the frame interval of the EPA node before the EPA node.

In some implementations, the total time each EPA node occupies is determined as follows: t4=t1+t2+t3+t5+t6+t7, where t4 represents the total time occupied by the EPA node preceding the EPA node, t1 represents the inter-node line delay from the EPA node preceding the EPA node or switch to the EPA node, t2 represents the node forwarding delay of the preceding EPA node or switch, t3 represents the message occupied time of the preceding EPA node, t5 represents the frame interval, t6 represents the message reservation time of the EPA node, and t7 represents the clock synchronization error of the EPA network.

In some implementations, the transmission offset time includes a forward transmission offset time and a reverse transmission offset time, and the forward transmission offset time and the reverse transmission offset time are set independently.

In some implementations, determining the transmission shaping time of the EPA node includes: and determining the transmission shaping time of the EPA nodes based on line delay between nodes, node forwarding delay, clock synchronization error and the number of EPA nodes contained in the EPA network.

In some implementations, the total time occupied by the ith EPA node is determined as follows:

wherein t1_i is the line delay between the ith EPA node and the (i+1) th EPA node or the node of the switch, t2_i is the node forwarding delay of the ith EPA node, t3_i is the message occupation time of the ith EPA node, t4_i is the total time occupied by the ith EPA node, t6 is the message reservation time, t7 represents the clock synchronization error of the EPA network, and n is the EPA node contained in the EPA network in the case that the EPA network is in a ring structureIs a number of (3).

wherein t1_i is the inter-node line delay from the ith EPA node to the (i+1) th EPA node, t2_i is the node forwarding delay of the ith EPA node, t3_i is the message occupation time of the ith EPA node, t4_i is the total time occupied by the ith EPA node, t6 is the message reservation time, t7 represents the clock synchronization error of the EPA network, n is the number of EPA nodes contained in the EPA network in the case that the EPA network is in a linear structure, and n is the longest-chain equipment number of the EPA network in the case that the EPA network is in a star structure.

In some implementations, the transmission offset time includes a forward transmission offset time and a reverse transmission offset time, and the forward transmission offset time is set equal to the reverse transmission offset time.

According to another aspect of the present invention, there is provided a control apparatus including: a processor and a memory, the memory comprising instructions executable by the processor, the processor configured to cause the node device to perform any of the methods described above.

According to another aspect of the invention, a computer readable storage medium is provided, on which computer program code is stored which, when run, performs the method as described above.

Drawings

The invention will be better understood and other objects, details, features and advantages of the invention will become more apparent by reference to the following description of specific embodiments thereof, which is given in the accompanying drawings.

Fig. 1A to 1D show schematic diagrams of exemplary EPA networks of different topologies according to embodiments of the present invention, respectively.

Fig. 2 shows a schematic diagram of a macrocycle of an EPA network according to an embodiment of the present invention.

Fig. 3 illustrates an exemplary flow chart of a method for configuration of an EPA network according to some embodiments of the present invention.

Fig. 4 shows an exemplary flow chart of a process for determining configuration parameters of an EPA network in accordance with an embodiment of the present invention.

Fig. 5 illustrates a further detailed flow chart of a process of determining a period time period length of a macrocycle, according to some embodiments of the invention.

Fig. 6A shows a schematic diagram of a periodic time slice for all EPA nodes in an EPA network.

Fig. 6B shows an exemplary schematic of a periodic time slice.

Fig. 7A illustrates a transmission schematic of periodic messages for various EPA nodes according to some embodiments of the present invention.

Fig. 7B shows a schematic diagram of transmission of periodic messages from various EPA nodes according to further embodiments of the present invention.

Fig. 7C illustrates a transmission schematic of periodic messages corresponding to fig. 7B for each EPA node 110 according to further embodiments of the present invention.

Fig. 7D and 7E illustrate transmission diagrams of periodic messages for respective EPA nodes according to further embodiments of the present invention, respectively.

Fig. 8 shows a more detailed flow chart of a process for determining the transmission offset time of an EPA node.

Fig. 9 shows a block diagram of a control device suitable for implementing embodiments of the present disclosure.

Detailed Description

Preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

In the following description, for the purposes of explanation of various inventive embodiments, certain specific details are set forth in order to provide a thorough understanding of the various inventive embodiments. One skilled in the relevant art will recognize, however, that an embodiment may be practiced without one or more of the specific details. In other instances, well-known devices, structures, and techniques associated with this application may not be shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

Throughout the specification and claims, unless the context requires otherwise, the word "comprise" and variations such as "comprises" and "comprising" will be understood to be open-ended, meaning of inclusion, i.e. to be interpreted to mean "including, but not limited to.

Reference throughout this specification to "one embodiment" or "some embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases "in one embodiment" or "in some embodiments" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for descriptive purposes only and are not limited to the size or other order of the objects described therein unless otherwise indicated.

In the EPA network, each node of the network adopts a time division multiplexing mode to carry out periodic communication, namely, on the premise of determining to work at the same time reference, a communication period with a specified time length is formulated according to a specific application scene of the system, which is also called a macro period, and the starting time and the ending time of the communication period of all nodes in the system are consistent. In general, one macrocycle may be divided into a cycle period and a non-cycle period, wherein the cycle period may be used to transmit cycle data (i.e., data sent periodically at a fixed frequency) for each node, while the non-cycle period may be declared by each node to send some burst data or to send system messages generated by the system itself.

Fig. 1A-1D show schematic diagrams of exemplary EPA networks 100 of different topologies according to embodiments of the present invention, respectively. EPA network 100 may include a plurality of EPA nodes 110 (4 EPA nodes 110-1, 110-2, 110-3, and 110-4 are schematically shown in FIGS. 1A-1D). Wherein EPA network 100 of FIG. 1A is a ring topology, and 4 EPA nodes 110-1, 110-2, 110-3, and 110-4 are connected in sequence to form a ring structure. EPA network 100 of FIG. 1B is a linear topology with 4 EPA nodes 110-1, 110-2, 110-3, and 110-4 connected in sequence, but the last EPA node 110-4 is no longer connected to the first EPA node 110-1. The EPA networks 100 of FIGS. 1C and 1D are both star topology, with each EPA node 110 connected by a switch 120. Except that in EPA network 100 of fig. 1C, 4 EPA nodes 110-1, 110-2, 110-3 and 110-4 are connected by one switch 120, respectively, whereas in EPA network 100 of fig. 1D, 4 EPA nodes 110-1, 110-2, 110-3 and 110-4 are connected by three (or two or more) switches 120 (i.e. switch 120-1, switch 120-2 and switch 120-3). Wherein EPA nodes 110 communicate with each other (and with switch 120) via an EPA bus based on the EPA protocol.

Each EPA node 110 has one or more Transmit (TX) ports (one is shown for each EPA node 110, i.e. transmit ports 1A, 2A, 3A and 4A, for example in fig. 1A to 1D) and one or more Receive (RX) ports (one is shown for each EPA node 110, i.e. receive ports 1B, 2B, 3B and 4B, for example in fig. 1A and 1B). Those skilled in the art will appreciate that the transmit ports 1A, 2A, 3A and 4A and the receive ports 1B, 2B, 3B and 4B may be bi-directional ports, respectively, or that corresponding receive ports (not shown) are additionally provided at the transmit ports 1A, 2A, 3A and 4A and corresponding transmit ports (not shown) are additionally provided at the receive ports 1B, 2B, 3B and 4B, such that the EPA network 100 supports both forward transmission (clockwise in fig. 1A or the direction from EPA node 110-1 to EPA node 110-4 in fig. 1B to 1D) and reverse transmission (counter-clockwise in fig. 1A or the direction from EPA node 110-4 to EPA node 110-1 in fig. 1B to 1D).

In EPA network 100, EPA nodes 110 communicate periodically with the same macrocycle.

In addition, fig. 1A to 1D show a control device 20, which control device 20 can be connected to the EPA network 100 via an ethernet network for controlling the EPA network 100, such as a configuration. Note that, in the case where the control device 20 is an ethernet device, a conversion device (not shown in the figure) is also required between the control device 20 and the EPA network 100 to convert the ethernet message transmitted by the control device 20 into an EPA message.

Fig. 2 shows a schematic diagram of a macrocycle T of the EPA network 100 according to an embodiment of the present invention. As shown in fig. 2, each macrocycle T may include a cycle period Tp and an aperiodic period Tnp.

The period time period Tp for each macrocycle T is used for each EPA node 110 to send a periodic message. Wherein each EPA node 110 in EPA network 100 is assigned a fixed period time slice during period time Tp for transmitting a periodic message of that EPA node 110 in a given communication mode, the start time (i.e. transmission offset time relative to the macro-period start time) and length of the period time slice is unique to each EPA node 110 without overlapping and conflicting with other EPA nodes 110. The period time Tp is primarily used to transmit user data for each EPA node 110, which is the primary data transmission time for the macrocycle. In this context, the EPA node 110 of the EPA network 100 that is the first to send a periodic message in the macrocycle T may be designated, which EPA node 110 is also referred to as the first EPA node of the EPA network 100. For example, EPA node 110-1 in FIG. 1A and FIG. 1B, which is connected to control device 20, may be designated as the first EPA node of EPA network 100, and EPA node 110-1 in FIG. 1C and FIG. 1D, which is connected to switch 120 or switch 120-1, may be designated as the first EPA node of EPA network 100.

In the following description, for example, it is described taking forward transmission as an example, for example, it is assumed that each EPA node 110 sequentially transmits respective period messages P1, P2, P3 and P4 in the order of EPA node 110-1→epa node 110-2→epa node 110-3→epa node 110-4 shown in fig. 1A to 1D, i.e., each period message is sequentially received through a receiving port of one EPA node 110 and then forwarded to the next EPA node 110 (or switch 120) through a transmitting port of that EPA node 110.

The non-periodic time period Tnp of the macrocycle T is a time period common to all EPA nodes 110, which may be declared by each EPA node 110 as different transmission time slices (e.g. declared in the periodic messages of the periodic time period Tp) according to actual needs, e.g. different transmission start time points and/or durations etc. During the non-periodic time period Tnp, the transmission time slices of all EPA nodes 110 still cannot overlap. Thus, during non-periodic time periods Tnp, each EPA node 110 can be used to send various control messages of unequal length or a few key messages.

The EPA network 100 needs to be configured with various operation parameters in advance, such as the macrocycle length, the cycle period length, and the transmission offset time of each EPA node 110, which are referred to as configuration parameters. Currently, configuration of EPA networks is mainly calculated and configured manually, and especially when the network topology or the number of nodes changes, it is necessary to perform recalculation and configuration update for each EPA node one by one, which requires a lot of labor cost.

In view of the above, in this context, before the EPA network starts to operate or when a change occurs, a control device (also referred to as an upper computer) connected to the EPA network automatically calculates one or more sets of configuration parameters for the EPA network according to information (such as topology, number of EPA nodes, user data amount, etc.) of the EPA network, and the control device may configure the EPA network in the form of an ethernet transmission (for example, in UDP messages) between the control device and the EPA network based on the determined or selected configuration parameters.

Fig. 3 illustrates an exemplary flow chart of a method 300 for configuration of EPA network 100 according to some embodiments of the present invention. The method 300 may be implemented, for example, by the control device 20 shown in fig. 1A and 1B.

At step 310, control device 20 obtains the number of EPA nodes included in EPA network 100 and the amount of user data for each EPA node 110.

As described above, the topology of EPA network 100 herein may be a ring structure as depicted in fig. 1A, a linear structure as shown in fig. 1B, or a star structure as shown in fig. 1C and 1D. Furthermore, those skilled in the art will appreciate that the concepts of the present invention, in addition to those specifically described below (e.g., a specific method of calculating the transmit offset time), are equally applicable to other topologies.

The amount of user data for each EPA node 110 may be the amount of data that each EPA node 110 is to transmit during the period time of each macrocycle during the present configuration adjustment, e.g., the amount of data that is periodically sensed by a sensor (not shown) associated with EPA node 110 to be transmitted, etc. The method 300 described herein may be re-executed to reconfigure as the amount of data that the EPA node 110 transmits during the period time of each macrocycle changes.

In addition, in some embodiments, in step 310, the control device 20 may further obtain the topology of the EPA network 100 for calculation of configuration parameters of the EPA network, i.e. calculate different configuration parameters for different topologies. Those skilled in the art will appreciate that the topology of EPA network 100 may be fixed or known in advance by control device 20 or control device 20 may uniformly calculate one or more sets of configuration parameters regardless of the topology.

Furthermore, as described below, for a star-structured EPA network 100, the configuration parameters (more specifically, the period time slice length or the transmission shaping time of each EPA node 110) depend not only on the number of EPA nodes 110 comprised by the EPA network 100, but also on the number of switches 120 comprised by the EPA network 100, i.e. the configuration parameters also depend on the maximum number of chain-link devices in the EPA network 100, as described in detail below. The maximum number of link devices may also be obtained by the control device 20 in advance through link detection or the like or configured in the control device 20 in advance by the user.

At step 320, control device 20 may determine configuration parameters for EPA network 100 based on the number of EPA nodes 110 included in EPA network 100 and the amount of user data for each EPA node 110 obtained at step 310. Herein, a set of corresponding configuration parameters may be configured for the EPA network 100 according to the user requirement of the EPA network 100 (e.g. whether the EPA network 100 needs to independently configure forward transmission and reverse transmission), or a plurality of sets of configuration parameters may be configured for the EPA network 100 for the user to select a set of configuration parameters for the EPA network 100 to configure according to the user requirement. For example, at least a minimum transmission offset time in different transmission modes (a first transmission mode and a second transmission mode described below) may be configured for each EPA node 110 of the EPA network 100, so as to calculate a set of configuration parameters, respectively, from which the control device 20 may select a set of configuration parameters for configuration according to the user's needs.

As described above, the configuration parameters include the length of the macro period (T), the length of the period time (Tp) of the EPA network 100, and the transmission offset time of each EPA node 110 in the macro period T. In some embodiments, the configuration parameters may include a minimum value of transmission offset time (i.e., minimum transmission offset time) of each EPA node 110 in different transmission modes. In addition, in some embodiments, the configuration parameters may further include a message reservation time Tr of each EPA node 110 during a period time Tp of the macrocycle. Note that this message reservation time Tr may be configured individually or in a unified manner for each EPA node 110 by the control apparatus 20, or may be stored in advance in each EPA node 110 (and the control apparatus 20) in the case of a predetermined value. The message reserved time Tr is used to prevent the message sent by the EPA node 110 from colliding with the messages sent by other EPA nodes 110 when the message is transmitted in the network.

In step 330, the control device 20 may configure the EPA network 100 based on the configuration parameters determined in step 320. For example, the control device 20 may package the determined configuration parameters or selected configuration parameters into UDP messages and send them to the EPA network 100 via its ethernet link with the EPA network 100. More specifically, the control device 20 may send the UDP packet to a conversion device (not shown in the figure) to convert the UDP packet into an EPA packet by the conversion device through protocol conversion, and send the EPA packet to each EPA node 110 to configure the EPA nodes 110. Here, the conversion device may be a stand alone device or may be integrated into the first EPA node 110 (e.g., EPA node 110-1) of EPA network 100.

Hereinafter, a process for determining configuration parameters of the EPA network 100 (step 320) according to an embodiment of the present invention will be described in detail with reference to fig. 4 to 8. In which fig. 4 shows an exemplary flow chart of a process (step 320) for determining configuration parameters of EPA network 100 in accordance with an embodiment of the present invention.

As shown in fig. 4, step 320 may include step 322, wherein control device 20 may determine a period time period (Tp) length of macrocycle T based on the number of EPA nodes 110 contained by EPA network 100 and the amount of user data per EPA node 110.

As shown in fig. 2 and described in detail below in connection with fig. 6A, the period time Tp of the macrocycle T consists of period time slots Tpi (i=1, 2, … …, m, where m is the number of EPA nodes 110 comprised by the EPA network 100) assigned to each EPA node 110, and the length of the period time slots Tpi assigned to each EPA node 110 in turn depends primarily on the amount of user data of that EPA node 110.

Furthermore, to ensure that transmissions between all EPA nodes 110 in EPA network 100 do not collide, the cycle time slice length of each EPA node 110 should also contain a message shaping time Tm, which may be determined in different ways depending on the different transmission modes, as described in detail below.

In addition, the period time slice length of each EPA node 110 may further include a message reservation time Tr preset for that EPA node 110. The message reservation time Tr may be the same or different time intervals set individually by the control device 20 for each EPA node 110, or may be the same or different time intervals pre-stored in each EPA node 110 or in the protocol stack space of the EPA network 100.

Fig. 5 shows a further detailed flow chart of a process of determining the period time period (Tp) length of the macrocycle T (step 322), according to some embodiments of the invention. Fig. 6A shows a schematic diagram of the period time slices (Tp 1, tp2, tp3, tp 4) of all EPA nodes 110 in EPA network 100, and fig. 6B shows an exemplary schematic diagram of one period time slice (e.g. Tp 1).

As shown in fig. 5, at step 3222, for each EPA node 110 (e.g., EPA node 110-1), control device 20 may determine a message occupancy time Ts1 for that EPA node 110-1 based on the amount of user data for that EPA node 110.

The message occupation time Ts1 may include one or more periodic messages P1 for carrying the user data amount of the EPA node 110. Herein, it is assumed that the periodic message P1 is an FRT (Fast Real Time) message suitable for the EPA protocol, and thus a plurality of periodic messages P1 are also labeled as FRT0, FRT1, … …, respectively, in fig. 6B.

When calculating the message occupation time Ts1 of the EPA node 110-1, the total number of bytes required for transmitting the corresponding user data amount may be determined based on the maximum frame length of the ethernet, and then the time required for transmitting the total number of bytes is calculated as the message occupation time of the EPA node according to the total number of bytes and the network transmission speed (for example, the network transmission speed of the gigabit ethernet is 125 MB/s).

Specifically, as shown in fig. 6B, each FRT packet includes an FRT packet header, a user data segment for carrying the amount of user data described above, an FCS (Frame Check Sequence ) field, and a frame interval.

For example, assuming that the amount of user data for EPA node 110-1 is 5000B, the individual FRT messages for EPA node 110-1 may be designed as follows in Table 1:

the message header length of FRT0 includes an ethernet message header of 28B and a MAC field of 14B, the FCS field length is fixed to 4B, and the frame interval is fixed to 12B. Thus, according to the user data volume 5000B of EPA node 110-1, FRT0, FRT1 and FRT2 can be set to 1530B, respectively, taking into account the maximum frame length of the ethernet, respectively, the user data segments allocated thereto are 1472B, 1476B and 1476B, respectively, and the user data segment of FRT4 is 5000B-1472B-1476 b=576B. Thus, under the above assumption, four periodic messages P1 for transmitting user data segments of EPA node 110-1 are 1530B, and 618B, respectively, as shown in Table 1.

Thus, the total number of bytes required to be transmitted by the EPA node 110-1 to transmit 5000B of user data is 5208B, and in gigabit ethernet, 8ns is required to transmit 1B, so the message occupation time Ts1 is 5208×8= 41664ns.

In step 3224, the control device 20 may determine the period time slice (Tp 1) length of the EPA node 110-1 based on the message occupation time Ts1, the transmission shaping time Tm1 and the message reservation time Tr1 of the EPA node 110-1 calculated in step 3222.

In some embodiments, control device 20 may set a transmission shaping time Tm for each EPA node 110 separately. More specifically, prior to step 3224, control device 20 may also determine a transmission shaping time for each EPA node 110 based at least on the inter-node line delay and the node forwarding delay for that EPA node 110.

Here, the determination of the transmission shaping time Tm of the EPA node 110 may be as described below with reference to fig. 8.

Thus, at step 3224, the period time slice (Tpi) length of each EPA node 110 can be determined as the sum of the message occupancy time Ts, the transmission shaping time Tm and the message reservation time Tr for that EPA node 110.

Continuing with fig. 5, at step 3226 control device 20 may sum the period time slice Tpi lengths of all EPA nodes 110 of EPA network 100 to determine the period time period (Tp) length of EPA network 100. That is, tp=Σtpi.

Continuing with fig. 4, at step 324, control device 20 may determine a macrocycle length T of EPA network 100 based on the period time length (Tp) and the non-period time length (Tnp).

Specifically, the control device 20 may determine the aperiodic time length Tnp of the macrocycle based on the aperiodic reserved time slices and the clock synchronization error set in advance.

For example, the aperiodic time Tnp can be determined as follows:

aperiodic time tnp=aperiodic reserved time slice+clock synchronization error

Furthermore, in some embodiments, the sync field may also be set in the aperiodic time Tnp, in which case the aperiodic time may be determined as follows:

aperiodic time tnp=synchronization field occupied time+aperiodic reserved time slice+clock synchronization error

Here, the sync field occupation time, the aperiodic reserved time slice, and the clock synchronization error are all preset or measured values, for example, the sync field occupation time may be directly specified or calculated based on the required sync field length and bandwidth, and the sync field length may be, for example, fixed 64 bytes, so that the calculation of the aperiodic time Tnp is not repeated here. Also, the clock synchronization error may be different for each EPA node 110. In this context, the maximum value of the clock synchronization errors of all EPA nodes 110 is used as the clock synchronization error in the configuration parameter calculation process.

The period time period length Tp and the non-period time length Tnp may then be summed to determine the macrocycle length T of the EPA network 100.

Continuing with fig. 4, for each EPA node 110 in EPA network 100, control device 20 can determine a transmission offset time for that EPA node 110 based on the transmission offset time of the previous EPA node for that EPA node 110 and the total time taken by the previous EPA node at step 326.

Fig. 7A illustrates a transmission schematic of periodic messages for various EPA nodes 110 according to some embodiments of the present invention. A schematic diagram of the transmission offset times of each EPA node 110 in the first transmission mode of the EPA network 100 is shown in fig. 7A. In the first transmission mode, each EPA node transmits the periodic message of the node after the periodic message of the previous EPA node completes transmission in the entire EPA network, and the forward transmission and the reverse transmission need to be considered, so that the mode is also called a loose mode. The forward transmission periodic messages are marked as N1, N2, N3 and N4, and the reverse transmission periodic messages are marked as N1', N2', N3 'and N4'. Note that the periodic messages N1, N2, N3, N4, etc. herein are different from the periodic messages P1, P2, P3, P4 or FRT messages described above in connection with fig. 6A and 6B, where the periodic messages N1, N2, N3, N4 correspond to the user data of each EPA node 110 and occupy the time Ts described above in connection with fig. 6A.

As shown in fig. 7A, it is assumed that the periodic message of each EPA node 110 is transmitted in a clockwise direction, and EPA nodes 110-1, 110-2, 110-3, and 110-4 sequentially transmit the message, whereby the scheduled transmission result as shown in fig. 7A can be obtained. In fig. 7A, T1 is the transmission offset time of EPA node 110-1 (if EPA node 110-1 is the first EPA node in EPA network 100, the transmission offset time may be set to 0), and T2 is the transmission offset time of EPA node 110-2. t1_i is the inter-node line delay from the ith EPA node to the (i+1) th EPA node, t2_i is the node forwarding delay of the ith EPA node, t3_i is the message occupation time (i.e. the message occupation time ts) of the ith EPA node, and t4_i is the total time occupied by the ith EPA node.

The following describes the EPA node 110-1 forward transmission process:

a periodic message N1 transmitted by a transmitting port 1A of the EPA node 110-1 at time T1 reaches a receiving port 2B of the EPA node 110-2 through time t1_1;

after receiving the periodic message N1, the receiving port 2B of the EPA node 110-2 forwards the periodic message from the transmitting port 2A of the EPA node 110-2 through the time t2_2;

the periodic message N1 forwarded by the transmitting port 2A of the EPA node 110-2 reaches the receiving port 3B of the EPA node 110-3 after t1_2 time;

after receiving the periodic message N1, the receiving port 3B of the EPA node 110-3 forwards the periodic message from the transmitting port 3A of the EPA node 110-3 through the time t2_3;

the periodic message N1 forwarded by the transmitting port 3A of the EPA node 110-3 reaches the receiving port 4B of the EPA node 110-4 after t1_3 time;

after receiving the periodic message N1, the receiving port 4B of the EPA node 110-4 forwards the periodic message N1 from the transmitting port 4A of the EPA node 110-4 through the time t2_4;

the periodic message N1 forwarded by the transmitting port 4A of EPA node 110-4 reaches the receiving port 1B of EPA node 110-1 over t1_4 time.

It can thus be seen that the total time t4_1 occupied by EPA node 110-1 includes the sum of EPA node 110-1 message occupied time t3_1, inter-node line delay t1_i, and node forwarding delay t2_i. In addition, the total time t4_1 occupied by the EPA node 110-1 may further include a message reserved time t6 (herein, the message reserved time t6 may be a message reserved time Tr set for each EPA node 110 separately or together as described above) and a clock synchronization error t7 of the EPA network 100. I.e.

（1）

Where t1_i is the inter-node line delay from the ith EPA node to the (i+1) th EPA node, t2_i is the node forwarding delay of the ith EPA node, t3_i is the message occupation time of the ith EPA node (i.e. the message occupation time ts described above), t4_i is the total time occupied by the ith EPA node, t6 is the message reservation time, t7 is the clock synchronization error of the EPA network 100, and n is the number of EPA nodes 110 contained in the EPA network 100 in the case where the EPA network 100 is in a ring structure.

More generally, for the ith EPA node 110, the total time t4_i occupied by the ith EPA node can be determined based on the inter-node line delay from the ith EPA node to the (i+1) th EPA node, the node forwarding delay t2_i of the ith EPA node, the message occupancy time t3_i of the ith EPA node (i.e. the message occupancy time tsi described above), the message reservation time t6 and the clock synchronization error t7 of the EPA network 100, and can be expressed as:

（2 ）

To avoid collision between the periodic messages of other EPA nodes 110 and the periodic message N1 of EPA node 110-1, other EPA nodes 110 should transmit the periodic messages at least at or after time t1+t4, so the transmission offset time of the next EPA node 110-2:

T2=T1+t4 （3 ）

in summary, when configuring the transmission offset time in the ring network, if the node occupies the time slice before other nodes have already occupied, the transmission offset time of the node=the transmission offset time of the previous node+the message occupancy time of the previous node+the transmission shaping time+the message reservation time.

Similarly, for EPA network 100 of the linear topology shown in FIG. 1B, periodic message N1, after reaching the last EPA node 110-4 and being processed, need not be sent through the send port 4A of EPA node 110-4 and received by the receive port 1B of the first EPA node 110-1. In this case, therefore, the total time taken up by EPA node 110-1 may be expressed as:

（4）

where t1_i is the inter-node line delay from the ith EPA node to the (i+1) th EPA node, t2_i is the node forwarding delay of the ith EPA node, t3_i is the message occupation time of the ith EPA node (i.e. the message occupation time ts described above), t4_i is the total time occupied by the ith EPA node, t6 is the message reservation time, t7 is the clock synchronization error of the EPA network 100, n is the number of EPA nodes 110 contained in the EPA network 100 in case where the EPA network 100 is a linear structure, and n is the number of longest-chain devices of the EPA network 100 in case where the EPA network 100 is a star structure.

（5）

for the star networks of fig. 1C and 1D, the total time occupied by the ith EPA node can be determined in a similar manner as equation (5) above.

Here, n has different meanings depending on the topology of EPA network 100. For example, for the EPA network 100 of the ring structure represented by the above formulas (1) and (2), n is the number of EPA nodes 110 included in the EPA network 100, where n=m. For the EPA network 100 of linear and star structures represented by the above formulas (4) and (5), n is the number of EPA nodes 110 included in the EPA network 100 of linear structure, where n=m, or n is the maximum number of chain devices of the EPA network 100 of star structure.

The maximum number of chain devices in EPA network 100 is the number of devices (including EPA node 110 and switch 120) that are included in the longest link in EPA network 100. For example, in FIG. 1C, the longest link of EPA network 100 is the link from EPA node 110-1 to switch 120 to any of EPA node 110-2 to EPA node 110-4, the corresponding longest link device number is 3, in FIG. 1D, the longest link of EPA network 100 is the link of EPA node 110-1→switch 120-2→switch 120-3→EPA node 110-4, and the corresponding longest link device number is 5. That is, the delay of all links and devices on the maximum transmission path of each EPA node 110 needs to be considered in determining the total time that each EPA node 110 occupies.

In the first transmission mode (loose mode) shown in fig. 7A, a forward transmission offset time for forward transmission and a reverse transmission offset time for reverse transmission may be set for each EPA node 110, respectively, and the forward transmission offset time and the reverse transmission offset time are set to be equal. For example, the forward transmission offset time may be made equal to the reverse transmission offset time by configuring the parameters (e.g., the packet reservation time t 6) in the above formulas (1) to (5).

Fig. 7B illustrates a transmission schematic of periodic messages for each EPA node 110 in accordance with further embodiments of the present invention. A schematic diagram of the transmission offset times of the respective EPA nodes 110 in the second transmission mode of the EPA network 100 is shown in fig. 7B. In this second transmission mode, the transmission offset time of the forward transmission and the transmission offset time of the reverse transmission of the EPA node 110 are independently configured, and there is no association between the two, and thus the EPA node is also referred to as a compact mode. Fig. 7B is a schematic diagram of unidirectional scheduling in a compact mode, where each EPA node sends a periodic message of its own node immediately after completing forwarding a previous periodic message. In FIG. 7B, T1 is the transmission offset time of EPA node 110-1 and T2 is the transmission offset time of EPA node 110-2. Similar to fig. 7A described above, t1_i is the inter-node line delay from the ith EPA node to the (i+1) th EPA node, t2_i is the node forwarding delay of the ith EPA node, t3_i is the message occupancy time of the ith EPA node (i.e., the message occupancy time ts described above), and t4_i is the total time occupied by the ith EPA node.

As can be seen in fig. 7B, the total time t4 occupied by EPA node 110-1 can be expressed as:

t4= t1+t2+t3+t5+t6+t7 （6）

that is, for the i-th EPA node 110, the total time t4_i occupied by the i-th EPA node may be determined for the inter-node line delay t1 from the i-1-th EPA node to the i-th EPA node, the node forwarding delay t2 of the i-1-th EPA node, the message occupied time t3 of the i-1-th EPA node (i.e., the message occupied time ts described above), the preset frame interval t5 (e.g., the frame interval 12B shown in Table 1), the message reserved time t6, and the clock synchronization error t7 of the EPA network 100.

If the EPA node 110-2 forwards the periodic message N1 of the EPA node 110-1 without collision with the periodic message N2 of the node, the EPA node 110-2 transmits the periodic message N2 of the node at least at the time T2 after the interval T4 from the T1, that is

T2=T1+t1+t2+t3+t5+t6+t7。（7）

In summary, the transmission offset time configured by the current EPA node 110=the transmission offset time of the previous EPA node+the inter-node line delay t1+the node forwarding delay t2+the packet occupation time t3+the frame interval t5+the packet reservation time t6+the clock synchronization error t7 of the previous EPA node.

It can be seen that in the compact mode, the transmission offset time interval of two adjacent EPA nodes is smaller than in the loose mode, so that the bandwidth utilization is high.

Meanwhile, note that when the transmission offset time is configured in the compact mode, the order in which the transmission offset time is configured should be consistent with the order in which the EPA nodes 110 are connected. For example, in the case of the ring topology shown in fig. 1A, when the transmission offset time of the forward transmission is configured, the four types of configuration can be performed in the order of EPA node 110-1, EPA node 110-2, EPA node 110-3, EPA node 110-4, EPA node 110-1, EPA node 110-2, and EPA node 110-3.

Fig. 7C illustrates a transmission schematic of periodic messages corresponding to fig. 7B for each EPA node 110 according to further embodiments of the present invention. Unlike in fig. 7B, fig. 7C is a schematic diagram illustrating bidirectional scheduling in a compact mode, where periodic messages transmitted in the forward direction are denoted as N1, N2, N3, N4, and periodic messages transmitted in the reverse direction are denoted as N1', N2', N3', N4'.

Taking the EPA network 100 of the ring topology shown in FIG. 1A as an example, it is assumed that periodic messages are transmitted in a clockwise direction as forward transmissions and in a counter-clockwise direction as reverse transmissions. Assuming that the forward transmission is transmitted in the manner of EPA node 110-1→EPA node 110-2→EPA node 110-3→EPA node 110-4 and the reverse transmission is transmitted in the manner of EPA node 110-1→EPA node 110-4→EPA node 110-3→EPA node 110-2, the scheduling transmission result as shown in FIG. 7C can be obtained in a similar manner as described above in connection with FIG. 7B.

In the second transmission mode (compact mode) shown in fig. 7C, a forward transmission offset time for forward transmission and a reverse transmission offset time for reverse transmission may be set for each EPA node 110, respectively, and the forward transmission offset time and the reverse transmission offset time may be set independently. That is, the forward transmission offset time and the reverse transmission offset time may be the same or different. For example, the same or different forward transmission offset time and reverse transmission offset time may be set by configuring parameters (e.g., message reservation time t 6) in the above formulas (6) and (7).

Fig. 7D and 7E illustrate transmission diagrams of periodic messages for respective EPA nodes 110 according to further embodiments of the present invention, respectively. Wherein fig. 7D shows a transmission schematic of each EPA node 110 in EPA network 100 according to the star structure shown in fig. 1C in a first transmission mode (loose mode); fig. 7E shows a transmission schematic of each EPA node 110 in EPA network 100 in accordance with the star structure shown in fig. 1D in a first transmission mode (loose mode). For fig. 7D and 7E, the transmission shaping time Tm and the transmission offset time for each EPA node can be determined similarly as described above in connection with fig. 7B.

In summary of the above, a more detailed flow chart of the process of determining the transmission offset time of EPA node 110 (step 326) may be summarized, as shown in FIG. 8.

In step 3262 of FIG. 8, for a first EPA node 110 (e.g., EPA node 110-1) in EPA network 100, the transmission offset for the first EPA node 110 is set to 0.

Next, at step 3264, for each EPA node 110 in EPA network 100 other than the first EPA node 110, a transmission shaping time Tm for that EPA node 110 may be determined based on at least inter-node line delay t1, node forwarding delay t2, and clock synchronization error t7 for EPA network 100 for the EPA node 110 prior to that EPA node 110.

In the second transmission mode, each EPA node transmits the periodic message of the node immediately after completing forwarding the previous periodic message, so in order to avoid interference of the adjacent periodic message, the transmission shaping time Tm may further include a frame interval t5 (for example, the frame interval of 12B described in the above-mentioned table 1), as follows by referring to the above-mentioned formula (6):

Tm=t1+t2+t5+t7 （8）

in the first transmission mode, each EPA node transmits the periodic message of the node after the periodic message of the previous EPA node completes transmission in the entire EPA network, so the transmission shaping time Tm should include the transmission delay of the periodic message of the node in the entire network minus the forwarding delay of the node itself, and for the EPA network with a ring structure, it can be known by referring to the above formula (6):

（9）

Where n is the number of EPA nodes 110 comprised by EPA network 100, where n=m.

For EPA networks of linear or star-type structure, reference to equation (2) above can be seen:

（10）

where n is the number of EPA nodes 110 included in the EPA network 100 with a linear structure, where n=m, or n is the number of longest link devices in the EPA network 100 with a star structure.

At step 3266, a total time t4 occupied by a previous EPA node may be determined based on the transmission shaping time Tm of the EPA node 110, the message occupancy time t3 and the message reservation time t6 of the previous EPA node.

In some embodiments, for example, for the loose mode described above in connection with fig. 7A, the total time taken by a previous EPA node may be determined based on inter-node line delay, node forwarding delay, the number of EPA nodes 110 comprised by EPA network 100, and the message taken time of the previous EPA node.

For example, in the example shown above in connection with fig. 7A, in the case of a ring topology, the total time taken up by the previous EPA node 110 can be expressed as:

（11）

in the case of a linear or star topology, the total time taken up by the previous EPA node 110 can be expressed as:

（12）

where n is the number of EPA nodes 110 included in the EPA network 100 when the EPA network 100 has a linear structure, that is, n=m, and n is the maximum number of devices in the EPA network 100 when the EPA network 100 has a star structure.

It will be appreciated by those skilled in the art that when actually performing the transmission offset time calculation, it is also possible to configure the EPA network 100 according to the above-described ring topology regardless of the topology structure, because the total time occupied by the nodes calculated in the ring topology is enough to ensure that the transmission offset time is not so large that the periodic messages collide.

In other embodiments, such as for the compact mode described above in connection with fig. 7B, the total time taken by a previous EPA node may be determined by summing the inter-node line delay, the node forwarding delay, and the message taken time of the previous EPA node for the current EPA node.

For example, in the example shown above in connection with fig. 7B, the total time t4 taken up by the previous EPA node 110 can be expressed as:

t4=t1+t2+t3+t5+t6+t7 （13）

finally, at step 3268, a transmission offset time for the EPA node 110 may be determined based on the transmission offset time for the EPA node 110 that is previous to the EPA node 110 and the message occupancy time for the previous EPA node 110.

For example, for the total time t4 occupied by the previous EPA node determined in the loose mode and the compact mode described above in connection with FIGS. 7A through 7E, respectively, it may be summed with the transmission offset of the previous EPA node of the EPA node, respectively, to determine the minimum of the transmission offset times of the EPA node in the two transmission modes, respectively.

On this basis, the control device 20 may also adjust the transmission offset time of each EPA node 110 by setting different message reservation times t6, so that different configuration parameters may be set according to the user's needs.

Fig. 9 shows a block diagram of a control device 900 suitable for implementing embodiments of the present disclosure. The control device 900 may be used to implement the control device 20 as shown in fig. 1A to 1D.

As shown in fig. 9, the control device 900 may include a processor 910. Processor 910 controls the operation and functions of control device 900. For example, in some embodiments, the processor 910 may perform various operations by means of instructions 930 stored in a memory 920 coupled thereto. Memory 920 may be of any suitable type suitable to the local technical environment and may be implemented using any suitable data storage technology including, but not limited to, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems. Although only one memory 920 is shown in fig. 9, those skilled in the art will appreciate that the control device 900 may include more physically distinct memories 920.

The processor 910 may be of any suitable type suitable to the local technical environment and may include, but is not limited to, one or more of a general purpose computer, a special purpose computer, a microprocessor, a Digital Signal Processor (DSP), and a processor-based multi-core processor architecture. The control device 900 may also include a plurality of processors 910. Processor 910 is coupled to transceiver 940, transceiver 940 may enable the reception and transmission of information by means of one or more communication components. All the features described above with reference to fig. 1A to 8 are applicable to the control apparatus 900 and are not described here.

By means of the scheme, before the EPA network starts to operate or when the EPA network is changed, the control device (also called an upper computer) connected with the EPA network can automatically calculate one or more groups of configuration parameters for the EPA network according to information (such as topological structure, node number, user data amount and the like) of the EPA network, each group of configuration parameters at least comprises the transmission offset time of each EPA node, and the control device can configure the EPA network in the form of Ethernet transmission (such as UDP message) between the control device and the EPA network based on the determined or the configuration parameters selected according to the user requirements, so that labor cost required for configuring the EPA network is greatly saved.

The present invention may be embodied as methods, apparatus, systems, and/or computer program products. The computer program product may include a computer readable storage medium having computer readable program instructions embodied thereon for performing various aspects of the present invention.

In one or more exemplary designs, the functions described herein may be implemented in hardware, software, firmware, or any combination thereof. For example, if implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium.

The various units of the apparatus disclosed herein may be implemented using discrete hardware components or may be integrally implemented on one hardware component, such as a processor. For example, the various illustrative logical blocks, modules, and circuits described in connection with the invention may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein.

Those of ordinary skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments of the invention may be implemented as electronic hardware, computer software, or combinations of both.

The previous description of the invention is provided to enable any person skilled in the art to make or use the present invention. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the present invention is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for configuration of an EPA network, comprising:

acquiring the number of EPA nodes contained in the EPA network and the user data volume of each EPA node;

determining configuration parameters of the EPA network based on the number of EPA nodes contained in the EPA network and the user data volume of each EPA node, wherein the configuration parameters at least comprise the length of a macro period, the length of a period time period of the EPA network and the transmission offset time of each EPA node in the macro period; and

and configuring the EPA network based on the configuration parameters.

2. The method of claim 1, wherein determining configuration parameters of the EPA network comprises:

determining the period time period length based on the number of EPA nodes contained in the EPA network and the amount of user data for each EPA node;

determining a macrocycle length of the EPA network based on the cycle time period length and the non-cycle time length; and

for each EPA node in the EPA network, determining a transmission offset time for the EPA node based on a transmission offset time for a previous EPA node to the EPA node and a total time occupied by the previous EPA node.

3. The method of claim 2, wherein determining the period time period length comprises:

for each EPA node, determining the message occupation time of the EPA node based on the user data volume of the EPA node;

determining the period time slice length of the EPA node based on the message occupation time, the transmission shaping time and the message reservation time of the EPA node; and

the period time slice lengths of all EPA nodes of the EPA network are summed to determine the period time slice length of the EPA network.

4. The method of claim 1, wherein determining a macrocycle length of the EPA network comprises:

determining the non-periodic time length based on a preset non-periodic reserved time slice and a clock synchronization error; and

the period time period length and the non-period time length are summed to determine a macrocycle length of the EPA network.

5. The method of claim 2, wherein determining a transmission offset time for the EPA node comprises:

for a first EPA node in the EPA network, setting the transmission offset time of the first EPA node to 0;

for each EPA node in the EPA network except for the first EPA node, determining a transmission shaping time for the EPA node based at least on an inter-node line delay, a node forwarding delay and a clock synchronization error for a node preceding the EPA node;

Determining the total time occupied by the previous EPA node based on the transmission shaping time of the EPA node, the message occupied time of the previous EPA node of the EPA node and the message reserved time; and is also provided with

Determining the transmission offset time of the EPA node based on the transmission offset time of the EPA node before the EPA node and the total time occupied by the EPA node before.

6. The method of claim 1, wherein the topology of the EPA network comprises a ring structure, a linear structure, or a star structure.

7. The method of claim 5, wherein determining a transmission shaping time of the EPA node comprises:

and determining the transmission shaping time of the EPA node based on the inter-node line delay, the node forwarding delay, the clock synchronization error and the frame interval of the EPA node before the EPA node.

8. The method of claim 7 wherein the total time each EPA node occupies is determined as follows:

t4= t1+t2+t3+t5+t6+t7，

wherein t4 represents the total time occupied by the node of the EPA before the node of EPA, t1 represents the inter-node line delay from the node of EPA before the node of EPA or the switch to the node of EPA, t2 represents the node forwarding delay of the node of EPA before the node of EPA or the switch, t3 represents the message occupied time of the node of EPA before the node of EPA, t5 represents the frame interval, t6 represents the message reserved time of the node of EPA, and t7 represents the clock synchronization error of the EPA network.

9. The method of claim 8, wherein the transmission offset time comprises a forward transmission offset time and a reverse transmission offset time, and the forward transmission offset time and the reverse transmission offset time are set independently.

10. The method of claim 5, wherein determining a transmission shaping time of the EPA node comprises:

and determining the transmission shaping time of the EPA nodes based on line delay between nodes, node forwarding delay, clock synchronization error and the number of EPA nodes contained in the EPA network.

11. The method of claim 10 wherein the total time occupied by the ith EPA node is determined as follows:

，

wherein t1_i is the line delay between the ith EPA node and the (i+1) th EPA node or the node of the switch, t2_i is the node forwarding delay of the ith EPA node, t3_i is the message occupation time of the ith EPA node, t4_i is the total time occupied by the ith EPA node, t6 is the message reservation time, t7 represents the clock synchronization error of the EPA network, and n is the number of EPA nodes contained in the EPA network under the condition that the EPA network is in a ring structure.

12. The method of claim 10 wherein the total time occupied by the ith EPA node is determined as follows:

，

Wherein t1_i is the line delay between the ith EPA node and the (i+1) th EPA node, t2_i is the node forwarding delay of the ith EPA node, t3_i is the message occupation time of the ith EPA node, t4_i is the total time occupied by the ith EPA node, t6 is the message reservation time, t7 represents the clock synchronization error of the EPA network, n is the number of EPA nodes contained in the EPA network in the case of a linear structure of the EPA network, and n is the longest line equipment number of the EPA network in the case of a star structure of the EPA network.

13. The method of claim 12, wherein the transmission offset time comprises a forward transmission offset time and a reverse transmission offset time, and the forward transmission offset time is set equal to the reverse transmission offset time.

14. A control apparatus comprising:

a processor and a memory, the memory comprising instructions executable by the processor, the processor configured to cause the node device to perform the method of any of claims 1-13.

15. A computer readable storage medium having stored thereon computer program code which, when executed, performs the method of any of claims 1 to 13.