A data communication control method and device for PLC communication

Abstract

This application relates to the field of PLC technology, specifically to a data communication control method and apparatus for PLC communication. The method includes: determining the congestion level of each communication link by real-time analysis of bandwidth utilization, average latency, and packet loss rate; obtaining the priority of data frames transmitted on each communication link, comparing it with the corresponding congestion level, and calculating the comparison feature value of the sending PLC device; adjusting the priority of data frames transmitted by the sending PLC device based on the comparison feature value; and transmitting data frames based on the adjusted priority of the data frames and the congestion level of the communication links. This avoids congestion exacerbation caused by improper path selection, improves communication efficiency between PLC devices, reduces PLC communication data loss and retransmission, and improves the utilization rate of industrial network communication resources.

Description

Technical Field

[0001] This application relates to the field of PLC technology, specifically to a data communication control method and device for PLC communication. Background Technology

[0002] A PLC, or Programmable Logic Controller, is a digital electronic system specifically designed for industrial automation. In large-scale industrial automated production systems, communication between PLC devices is one of the core elements for achieving efficient, intelligent, and reliable operation. As a crucial component of industrial automated production, PLC devices are connected through communication networks, forming an organic whole that enables the entire system to work collaboratively, flexibly adapt to changes, and continuously optimize performance. This communication not only achieves data and resource sharing but also provides a solid technical foundation for distributed control, fault diagnosis, production efficiency improvement, and remote monitoring of the system.

[0003] Publication No. CN119200498A discloses a PLC data communication control system and method. In small-scale PLC communication scenarios, this method can effectively schedule PLCs by calculating the comprehensive polling weight and determining the polling period, ensuring that each PLC can complete communication within a specified time and avoiding network congestion and communication delays. However, as production scale expands and processes are adjusted, the number of PLCs increases significantly, and the above-disclosed method faces the problem of expansion difficulties, increasing the complexity of network configuration and management, and easily leading to uneven distribution of communication resources. During peak PLC communication periods, communication congestion and low utilization of communication resources may occur. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this application is to provide a data communication control method and device for PLC communication, the specific technical solution of which is as follows:

[0005] In a first aspect, embodiments of this application provide a data communication control method for PLC communication, the method comprising the following steps:

[0006] An evaluation period is set up. By collecting the number of input bytes and output bytes, the total bandwidth of the communication link, the timestamp data of data frames at the sending and receiving ends, the total number of transmitted data frames, and the number of data frames lost during the evaluation period, the bandwidth utilization, average latency, and packet loss rate of each communication link during the evaluation period are determined.

[0007] Based on the bandwidth utilization, average latency, and packet loss rate, the congested links in all communication links are identified, and the congestion characteristic values ​​of the congested links in the current evaluation period are calculated.

[0008] Obtain the priority of each data frame; set the congestion level for the congested link and the other communication links respectively, wherein the congestion level of the congested link is determined based on the congestion feature value and the preset highest congestion level; calculate the comparison feature value of the sending PLC device in the evaluation period based on the difference between the priority of the data frame transmitted by the sending PLC device and the congestion level of the corresponding communication link.

[0009] The priority of data frames transmitted by the sending PLC device is adjusted based on the comparison feature values;

[0010] Data frame transmission is based on the adjusted data frame priority and the congestion level of the communication link.

[0011] In one embodiment, the expression for the bandwidth utilization rate is:

[0012] In the formula, This represents the bandwidth utilization rate of the current communication link during the evaluation period. and These represent the number of input bytes and output bytes of the current communication link during the evaluation period, respectively. This indicates the total bandwidth of the current communication link; This indicates the duration of the evaluation period.

[0013] In one embodiment, the process of obtaining the average latency and packet loss rate is as follows:

[0014] The difference between the timestamp data of the data frame at the receiving end and the timestamp data at the sending end is calculated as the delay time of a single data frame; the average delay time of all data frames transmitted by the current communication link within the evaluation period is recorded as the average delay time of the current communication link within the evaluation period.

[0015] The ratio of the number of data frames lost during the evaluation period to the total number of data frames transmitted on the current communication link is denoted as the packet loss rate of the current communication link during the evaluation period.

[0016] In one embodiment, the process of acquiring the congested link is as follows:

[0017] Set a bandwidth utilization threshold, an average latency threshold, and a packet loss rate threshold. If any one of the following indicators of bandwidth utilization, average latency, or packet loss rate of each communication link exceeds the corresponding threshold during the evaluation period, then each communication link during the evaluation period will be marked as a congested link.

[0018] In one embodiment, the expression for the congestion feature value is:

[0019] In the formula, This indicates the congestion characteristic value of the currently congested link during the evaluation period; , and These represent the bandwidth utilization, average latency, and packet loss rate of the currently congested link during the evaluation period, respectively. This represents the maximum average latency of all communication links other than the currently congested link during the evaluation period. , and All of these are preset parameter weights, where, and .

[0020] In one embodiment, setting congestion levels for the congested link and the remaining communication links respectively specifically involves:

[0021] During the current assessment period, the congestion level of communication links that are not marked as congested links is set to 0.

[0022] The congestion level of a congested link is calculated using the following expression: In the formula, This indicates the congestion level of the congested link within the current assessment period; This represents the congestion characteristic value of the congested link within the current assessment period; This represents the maximum value of the congestion characteristic value for all communication links passing through the fieldbus coupler; This indicates the preset maximum congestion level; This represents the function for rounding up.

[0023] In one embodiment, the process of obtaining the alignment feature values ​​is as follows:

[0024] During the evaluation period, the difference between the priority of each data frame and the congestion level of the communication link transmitting the data frame is calculated and recorded as the first difference; the mean of the squares of the first difference of all data frames sent by the transmitting PLC device to the fieldbus coupler during the evaluation period is recorded as the comparison feature value of the transmitting PLC device during the evaluation period.

[0025] In one embodiment, adjusting the priority of data frames transmitted by the sending PLC device based on comparison feature values ​​specifically involves:

[0026] If the comparison feature value of the transmitting PLC device is lower than the preset comparison feature threshold during the evaluation period, the priority value of the data frame of the transmitting PLC device in the next evaluation period will be increased by one level.

[0027] In one embodiment, the data frame transmission based on the adjusted data frame priority and the congestion level of the communication link specifically includes:

[0028] During the current evaluation period, all data frames to be sent are sorted from high to low according to their adjusted priorities, with high-priority data frames being processed first. For each data frame to be sent, the communication link with the lowest congestion level in the fieldbus coupler is selected for transmission.

[0029] Secondly, embodiments of this application also provide a data communication control device for PLC communication, including a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of any of the methods described above.

[0030] The embodiments of this application have at least the following beneficial effects:

[0031] This application adjusts the congestion control mechanism based on the characteristics of industrial network data frames to effectively cope with the congestion of communication links, prevent communication link overload, avoid congestion problems caused by improper path selection, improve data transmission efficiency, and enhance network reliability and stability.

[0032] This application determines the congestion level of each communication link by real-time analysis of bandwidth utilization, average latency, and packet loss rate; obtains the priority of data frames transmitted on each communication link, compares it with the corresponding congestion level, and calculates the comparison feature value of the sending PLC device; adjusts the priority of data frames transmitted by the sending PLC device based on the comparison feature value; and transmits data frames based on the adjusted data frame priority and the congestion level of the communication link. It optimizes the organizational structure and routing strategy of the industrial network, enabling more efficient data transmission within the network and avoiding congestion exacerbation caused by improper path selection. This improves the communication efficiency between PLC devices, reduces PLC communication data loss and retransmission, and enhances the utilization rate of industrial network communication resources. Attached Figure Description

[0033] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 A flowchart illustrating the steps of a data communication control method for PLC communication, provided in one embodiment of this application;

[0035] Figure 2 This is a schematic diagram illustrating the process of obtaining the comparison feature values. Detailed Implementation

[0036] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a data communication control method and apparatus for PLC communication proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0038] The following description, in conjunction with the accompanying drawings, details a specific scheme for a data communication control method and device for PLC communication provided in this application.

[0039] Please see Figure 1 The diagram illustrates a flowchart of a data communication control method for PLC communication according to an embodiment of this application. The method includes the following steps:

[0040] Step S1: Set the evaluation period. By collecting the number of input bytes and output bytes, the total bandwidth of the communication link, the timestamp data of data frames at the sending and receiving ends, the total number of transmitted data frames, and the number of data frames lost during the evaluation period, determine the bandwidth utilization, average latency, and packet loss rate of each communication link during the evaluation period.

[0041] In large-scale industrial automated production systems, each PLC needs to communicate with other PLCs. The large number of connections in industrial networks makes congestion prone to occur. When using the PROFINET protocol for communication, the frequency of communication between different PLC devices varies at different times, resulting in varying degrees of congestion on the communication links between devices. Current communication control priority management does not consider the congestion status of different communication links, which may exacerbate network congestion and reduce communication efficiency.

[0042] The PROFINET protocol uses IEEE 802.1Q VLAN tags to assign priorities, but these priorities are typically statically configured by default and cannot be dynamically adjusted based on real-time link congestion. If communication traffic between some PLCs is high and the priority setting is low, these links may become continuously congested, while some links may become idle, resulting in wasted resources.

[0043] Analyze metrics such as bandwidth utilization, latency, and packet loss rate of communication links to assess congestion status of each link in real time and adjust link allocation accordingly.

[0044] First, an evaluation period is set. Preferably, in this embodiment, the evaluation period is set to 1 second. In other embodiments of this application, the implementer can set the duration of the evaluation period according to actual conditions. This embodiment uses a fieldbus coupler to obtain the number of input and output bytes of each communication link, the total bandwidth of the communication link, the timestamp data of data frames at the sending and receiving ends, the total number of transmitted data frames, and the number of lost data frames within the evaluation period via the SNMP protocol.

[0045] It should be noted that the fieldbus coupler adopts the PROFINET communication protocol, has multiple RJ45 interfaces, integrates switch functions, supports SNMP (Simple Network Management Protocol), and can be expanded with multiple local modules such as digital, analog, temperature, pulse, and communication gateways. It also features diagnostic alarms, process alarms, and module plug-in / removal alarms. The fieldbus coupler is slidably mounted with other modules via DIN rails. The fieldbus coupler has four LEDs: PWR, RUN, SF, and ERR. A bright green PWR light indicates normal power supply, while no green light indicates an abnormal power supply. A bright green RUN light indicates normal communication, while no green light indicates the initial state. A bright red SF light indicates forced operation mode; flashing red indicates configuration errors, coupler errors, module errors, or new diagnostic information; no red light indicates normal operation. A bright red ERR light indicates the fieldbus coupler is offline; flashing red light indicates inconsistent expansion module configuration; no red light indicates no communication fault.

[0046] Then, for each communication link, its bandwidth utilization rate during the evaluation period is calculated, expressed as:

[0047]

[0048] In the formula, This represents the bandwidth utilization rate of the current communication link during the evaluation period. and These represent the number of input bytes and output bytes of the current communication link during the evaluation period, respectively. This indicates the total bandwidth of the current communication link; This indicates the duration of the evaluation period.

[0049] Furthermore, the difference between the timestamp data of the data frame at the receiving end and its timestamp data at the sending end is calculated as the delay time of a single data frame; and the average delay time of all data frames transmitted by the current communication link within the evaluation period is recorded as the average delay time of the current communication link within the evaluation period.

[0050] Furthermore, the ratio of the number of data frames lost during the evaluation period to the total number of data frames transmitted on the current communication link is denoted as the packet loss rate of the current communication link during the evaluation period.

[0051] Step S2: Based on the bandwidth utilization, average latency, and packet loss rate, identify the congested links among all communication links and calculate the congestion characteristic value of the congested links in the current evaluation period.

[0052] (1) In this embodiment of the application, the bandwidth utilization threshold is set to 0.8, the average latency threshold is set to 50ms, and the packet loss rate threshold is set to 0.05. In other embodiments of the application, the implementer may set the bandwidth utilization threshold, average latency threshold, and packet loss rate threshold according to the requirements of the industrial communication network performance.

[0053] The bandwidth utilization, average latency, and packet loss rate of the current communication link during the evaluation period are compared with their corresponding thresholds. If any one of these three indicators of the current communication link during the evaluation period exceeds its corresponding threshold, the communication link during the evaluation period is marked as a congested link.

[0054] (2) In industrial automation production systems, some emergency events, such as fault diagnosis and equipment restart, can lead to a surge in communication volume, which can cause local congestion. In addition, in industrial communication networks, the amount of data transmitted between PLC devices per unit time is relatively small, and in order to meet the real-time requirements of industrial production for data communication, the data frames are usually small, and the number of data frames transmitted per unit time is relatively large. Compared with other communication networks, different stages of congestion in industrial communication networks have different impacts on the performance indicators of the communication link.

[0055] In the initial stage, data frame queuing began to appear, and the latency increased slightly, but it did not have a significant impact on system performance, and bandwidth utilization began to rise.

[0056] During the development phase, data frame queuing time increases and bandwidth utilization is relatively high. Due to the small size and large number of data frames, latency increases significantly, and some data frames begin to be dropped, but the packet loss rate is still low.

[0057] In severe cases, the link becomes completely saturated, with a large number of queued data frames, extremely high latency, and a significantly increased packet loss rate, which may affect system functionality.

[0058] Therefore, for data frame transmission in industrial networks, an increased packet loss rate reflects the most severe communication link congestion, followed by average latency, which is the least effective indicator of link congestion, while bandwidth utilization is the least effective.

[0059] Based on the bandwidth utilization, average latency, and packet loss rate of the congested links during the evaluation period, the congestion characteristic value is calculated for each congested link, expressed as:

[0060]

[0061] In the formula, This indicates the congestion characteristic value of the currently congested link during the evaluation period; , and These represent the bandwidth utilization, average latency, and packet loss rate of the currently congested link during the evaluation period, respectively. This represents the maximum average latency of all communication links other than the currently congested link during the evaluation period. This indicates the relative delay time of the currently congested link; , and All of these are preset parameter weights.

[0062] Considering that different metric values ​​reflect different stages and degrees of congestion in congested links, different weights are assigned to bandwidth utilization, average latency, and packet loss rate to improve the accuracy of assessing congestion in industrial communication networks and avoid frequent adjustments to subsequent congestion control strategies, which could lead to low routing efficiency. The weights of the three parameters in this application satisfy the following... and Preferably, in the embodiments of this application, , and The values ​​are set to 0.2, 0.3, and 0.5, respectively. As other embodiments of this application, implementers can set the values ​​themselves according to actual circumstances. , and The value of .

[0063] F reflects the degree of congestion of the link; the larger the congestion characteristic value, the more severe the congestion of the link.

[0064] Step S3: Obtain the priority of each data frame; set the congestion level for the congested link and the other communication links respectively, wherein the congestion level of the congested link is determined based on the congestion feature value and the preset highest congestion level; calculate the comparison feature value of the sending PLC device in the evaluation period based on the difference between the priority of the data frame transmitted by the sending PLC device and the congestion level of the corresponding communication link.

[0065] Different devices have different communication priorities. Simply allocating communication links can not only exacerbate communication congestion and reduce communication efficiency, but also cause some high-priority data frames to have excessively long queuing delays, affecting industrial production.

[0066] The PROFINET communication protocol data frames contain priority data tags, with priority levels ranging from 0 to 7, for a total of 8 levels. A higher priority value indicates a higher real-time requirement for the data frame's transmission.

[0067] This application assigns congestion level labels to each communication link passing through the fieldbus coupler, with congestion level values ​​ranging from 0 to 7, for a total of 8 levels. The specific congestion levels for each communication link are as follows:

[0068] Within the current assessment period, communication links not marked as congested are set to a congestion level of 0; for congested links, their congestion level is calculated using the following expression:

[0069]

[0070] In the formula, This indicates the congestion level of the congested link within the current assessment period; This represents the congestion characteristic value of the congested link within the current assessment period; This represents the maximum value of the congestion characteristic value for all communication links passing through the fieldbus coupler; This indicates the highest congestion level, as described in the embodiments of this application. The value is 7; This represents the function for rounding up.

[0071] The higher the congestion level value for each communication link, the more severe the congestion.

[0072] Step S4: Adjust the priority of the data frames transmitted by the sending PLC device based on the comparison feature values.

[0073] For each transmitting PLC device, within the evaluation period, the difference between the priority of each data frame and the congestion level of the communication link transmitting the data frame is calculated and recorded as the first difference; the mean of the squares of the first differences of all data frames sent by the transmitting PLC device to the fieldbus coupler within the evaluation period is recorded as the comparison feature value of the transmitting PLC device within the evaluation period.

[0074] A larger alignment feature value indicates that more high-priority data frames are allocated to communication links with lower congestion levels for transmission, or more low-priority data frames are allocated to communication links with higher congestion levels for transmission. Conversely, a smaller alignment feature value indicates that more high-priority data frames are allocated to communication links with higher congestion levels for transmission, or more low-priority data frames are allocated to communication links with lower congestion levels for transmission.

[0075] Furthermore, the priority of the data frames transmitted by the sending PLC device is adjusted based on the comparison feature value of the sending PLC device, specifically as follows:

[0076] In a preferred embodiment of this application, the comparison feature threshold is set to 9. In other embodiments of this application, the implementer may set the comparison feature threshold according to the actual situation.

[0077] If the comparison feature value of the transmitting PLC device is lower than the comparison feature threshold during the evaluation period, the priority value of the data frame of the transmitting PLC device in the next evaluation period will be increased by one level. If the priority value of the data frame has already reached the highest priority, no priority adjustment will be made.

[0078] By analyzing the congestion level of the communication link and the priority of data frames in the current evaluation period, the system can dynamically adjust the priority of data frame transmission in the next evaluation period to ensure that high-priority data can still be transmitted in a timely manner even under congestion.

[0079] Step S5: Data frame transmission is performed based on the adjusted data frame priority and the congestion level of the communication link.

[0080] In large-scale industrial automated production systems, the rational allocation of communication links is crucial to ensure the efficient transmission of critical data. This application is based on the PROFINET protocol and allocates communication links according to data frame priority and the congestion level of the communication links.

[0081] First, the adjusted priorities of all data frames to be sent within the current evaluation period are determined using the above method. All data frames to be sent are sorted from high to low according to their priorities, and high-priority data frames are processed first to ensure that they can be transmitted preferentially on links with less congestion.

[0082] Secondly, for each data frame to be sent, the communication link with the lowest congestion level among the fieldbus couplers in the current evaluation period is selected for transmission.

[0083] If multiple communication links have the same congestion level, the link with the fewest hops is selected first to reduce the additional latency caused by the fieldbus coupler data processing. If links with the same hop count still exist, one is randomly selected as the communication link for the current data frame.

[0084] Finally, based on the selected communication link, the MAC address table of the fieldbus coupler is modified. Simultaneously, the congestion status changes of each link are monitored in real time, and their congestion levels are adjusted accordingly to reassess and adjust the link allocation scheme for subsequent data frames.

[0085] A schematic diagram of the process of obtaining the comparison feature values ​​is shown below. Figure 2 As shown.

[0086] Based on the same inventive concept as the above method, this application embodiment also provides a data communication control device for PLC communication, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any one of the above-described data communication control methods for PLC communication.

[0087] In summary, the embodiments of this application provide a data communication control method for PLC communication. Based on the characteristics of industrial network data frames, the congestion control mechanism is adjusted to effectively cope with the congestion of the communication link, prevent the communication link from being overloaded, avoid congestion problems caused by improper path selection, improve the efficiency of data transmission, and enhance the reliability and stability of the network.

[0088] This application determines the congestion level of each communication link by analyzing the bandwidth utilization, average latency, and packet loss rate of each link in real time; it obtains the priority of the data frames transmitted on each communication link, compares them with the corresponding congestion level, and calculates the comparison feature value of the sending PLC device; it adjusts the priority of the data frames transmitted by the sending PLC device based on the comparison feature value; and it transmits data frames based on the adjusted priority of the data frames and the congestion level of the communication link. This optimization of the industrial network's organizational structure and routing strategy enables more efficient data transmission within the network, avoids congestion exacerbation due to improper path selection, improves communication efficiency between PLC devices, reduces PLC communication data loss and retransmission, and enhances the utilization rate of industrial network communication resources.

[0089] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this application. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous.

[0090] The various embodiments in this application are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0091] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this application should be included within the protection scope of this application.

Claims

1. A data communication control method for PLC communication, characterized in that, The method includes the following steps: An evaluation period is set up. By collecting the number of input bytes and output bytes, the total bandwidth of the communication link, the timestamp data of data frames at the sending and receiving ends, the total number of transmitted data frames, and the number of data frames lost during the evaluation period, the bandwidth utilization, average latency, and packet loss rate of each communication link during the evaluation period are determined. Based on the bandwidth utilization, average latency, and packet loss rate, the congested links in all communication links are identified, and the congestion characteristic values ​​of the congested links in the current evaluation period are calculated. The priority of each data frame is obtained. The higher the priority value, the higher the real-time requirement of the data frame for transmission. Congestion levels are set for congested links and other communication links respectively. The congestion level of each congested link is determined based on the congestion feature value and the preset maximum congestion level. The higher the congestion level value of each communication link, the more severe the congestion. The comparison feature value of the sending PLC device in the evaluation period is calculated based on the difference between the priority of the data frame transmitted by the sending PLC device and the congestion level of the corresponding communication link. The priority of data frames transmitted by the sending PLC device is adjusted based on the comparison feature values; Data frame transmission is based on the adjusted data frame priority and the congestion level of the communication link. The process for obtaining the comparison feature values ​​is as follows: During the evaluation period, the difference between the priority of each data frame and the congestion level of the communication link transmitting the data frame is calculated and recorded as the first difference; the mean of the squares of the first difference of all data frames sent by the transmitting PLC device to the fieldbus coupler during the evaluation period is recorded as the comparison feature value of the transmitting PLC device during the evaluation period.

2. The data communication control method for PLC communication as described in claim 1, characterized in that, The expression for the bandwidth utilization rate is: In the formula, This represents the bandwidth utilization rate of the current communication link during the evaluation period. and These represent the number of input bytes and output bytes of the current communication link during the evaluation period, respectively. This indicates the total bandwidth of the current communication link; This indicates the duration of the evaluation period.

3. The data communication control method for PLC communication as described in claim 1, characterized in that, The process for obtaining the average latency and packet loss rate is as follows: The difference between the timestamp data of the data frame at the receiving end and the timestamp data at the sending end is calculated as the delay time of a single data frame; the average delay time of all data frames transmitted by the current communication link within the evaluation period is recorded as the average delay time of the current communication link within the evaluation period. The ratio of the number of data frames lost during the evaluation period to the total number of data frames transmitted on the current communication link is denoted as the packet loss rate of the current communication link during the evaluation period.

4. The data communication control method for PLC communication as described in claim 1, characterized in that, The process of obtaining the congested link is as follows: Set a bandwidth utilization threshold, an average latency threshold, and a packet loss rate threshold. If any one of the following indicators of bandwidth utilization, average latency, or packet loss rate of each communication link exceeds the corresponding threshold during the evaluation period, then each communication link during the evaluation period will be marked as a congested link.

5. The data communication control method for PLC communication as described in claim 1, characterized in that, The expression for the congestion feature value is: In the formula, This indicates the congestion characteristic value of the currently congested link during the evaluation period; , and These represent the bandwidth utilization, average latency, and packet loss rate of the currently congested link during the evaluation period, respectively. This represents the maximum average latency of all communication links other than the currently congested link during the evaluation period; , and All of these are preset parameter weights, where, and .

6. The data communication control method for PLC communication as described in claim 1, characterized in that, The congestion level settings for congested links and other communication links are as follows: During the current assessment period, the congestion level of communication links that are not marked as congested links is set to 0. The congestion level of a congested link is calculated using the following expression: In the formula, This indicates the congestion level of the congested link within the current assessment period; This represents the congestion characteristic value of the congested link within the current assessment period; This represents the maximum value of the congestion characteristic value for all communication links passing through the fieldbus coupler; This indicates the preset maximum congestion level; This represents the function for rounding up.

7. The data communication control method for PLC communication as described in claim 1, characterized in that, The adjustment of the priority of data frames transmitted by the sending PLC device based on comparison feature values ​​is specifically as follows: If the comparison feature value of the transmitting PLC device is lower than the preset comparison feature threshold during the evaluation period, the priority value of the data frame of the transmitting PLC device in the next evaluation period will be increased by one level.

8. The data communication control method for PLC communication as described in claim 1, characterized in that, The data frame transmission based on the adjusted data frame priority and the congestion level of the communication link specifically includes: During the current evaluation period, all data frames to be sent are sorted from high to low according to their adjusted priorities, with high-priority data frames being processed first. For each data frame to be sent, the communication link with the lowest congestion level in the fieldbus coupler is selected for transmission.

9. A data communication control device for PLC communication, characterized in that, The method includes a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of the method as described in any one of claims 1-8.

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