Joint scheduling method based on BACnet / IP and TSN

Abstract

The invention belongs to the technical field of industrial networks, and particularly relates to a joint scheduling method based on a BACnet / IP and a TSN network, which comprises the following steps: acquiring a BAcnet / IP data frame, performing VLAN label adding processing on a data link layer, and identifying the traffic priority of the BAcnet / IP data frame in the TSN network; a BAcnet / IP data frame is divided into periodic traffic and non-periodic traffic, the periodic traffic allocates periodic queues according to traffic priorities, a periodic data scheduling method based on load adaptive priorities is adopted, scheduling is carried out in a periodic time period of each continuous period, the non-periodic traffic allocates non-periodic queues according to traffic priorities, and scheduling is carried out in a periodic time period of each continuous period. Scheduling in a non-periodic time period of each continuous period by adopting a dynamic priority adjustment strategy; according to the method, interconnection and intercommunication of the two networks are realized, periodic flow transmission is preferentially ensured on the premise of not exceeding given resources, the time delay of the BACnet / IP network is reduced, and key tasks are ensured to be completed on time.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial networks, and in particular relates to a joint scheduling method based on BACnet / IP and TSN networks. Background Art

[0002] With the rapid development of industrial automation and building automation, the application of communication technology in these fields has become increasingly important. In building and industrial automation systems, BACnet / IP (Building Automation and ControlNetworks over Internet Protocol) has become one of the most widely used communication protocols due to its standardization, interoperability and scalability. BACnet / IP is a communication protocol based on IP network, mainly used for communication between devices in building automation systems, covering multiple fields such as air conditioning, lighting, security, fire protection, etc. Its advantage is that it can communicate seamlessly between devices from different manufacturers and provide a unified standard interface, thereby improving the interoperability and flexibility of the system. Because BACnet / IP uses standard Ethernet technology and existing IP infrastructure, it has a low deployment cost and supports remote monitoring and management functions, which is suitable for distributed automation systems and smart building scenarios. At the same time, with the development of the Internet of Things (IoT), BACnet / IP can also be integrated with other modern network protocols, further enhancing its application prospects in building and industrial control.

[0003] Time-Sensitive Networking (TSN) is a series of protocol standards developed by the IEEE 802.1TSN working group to provide high-reliability, low-latency, and low-jitter Ethernet transmission capabilities for industrial control networks. The main feature of TSN is the ability to effectively transmit data streams of different categories and priorities, thereby ensuring that mission-critical traffic arrives on time. Through precise time synchronization and traffic scheduling, TSN has become a key technology to support real-time communications in industry and building automation.

[0004] Existing BACnet / IP and TSN fusion solutions usually rely on basic marking of BACnet / IP traffic, such as configuring network device ports to add a single VLAN tag to identify different traffic priorities. This method can initially achieve interoperability between BACnet / IP and TSN networks, but because BACnet / IP itself does not have an accurate scheduling mechanism for different types of traffic, this simple fusion solution cannot fully utilize the low latency and high reliability advantages of TSN. When faced with traffic of different priorities, it is impossible to effectively distinguish between critical tasks and ordinary task flows, thus affecting the real-time transmission of critical data flows. Summary of the invention

[0005] To solve the above problems, the present invention provides a joint scheduling method based on BACnet / IP and TSN network, comprising the following steps:

[0006] S1. Build a joint system including BAcnet / IP network and TSN network;

[0007] S2. Obtain a BAcnet / IP data frame from the BAcnet / IP network, the BAcnet / IP data frame is subjected to VLAN tagging at the data link layer, and the traffic priority of the BACnet / IP data frame in the TSN network is identified;

[0008] S3. Determine whether the BAcnet / IP data frame is periodic traffic based on its transmission characteristics;

[0009] S4. If the BACnet / IP data frame is periodic traffic, the BACnet / IP data frame is allocated to the corresponding periodic queue according to the traffic priority, and the periodic traffic is scheduled using a periodic data scheduling method based on load adaptive priority;

[0010] S5. If the BACnet / IP data frame is aperiodic traffic, the BACnet / IP data frame is allocated to the corresponding aperiodic queue according to the traffic priority, and the scheduling of the aperiodic traffic is realized by using a dynamic priority adjustment strategy.

[0011] Beneficial effects of the present invention:

[0012] In order to further improve the integration effect of BACnet / IP and TSN, the present invention adds a four-byte VLAN tag after the source MAC address of the BACnet / IP data frame at the data link layer to convert it into a TSN data frame, so that the TSN switch can schedule the BACnet / IP data frame. And according to the different requirements of different types of BACnet / IP data streams for real-time and determinism, different values ​​are filled in the PCP field in the VLAN tag, thereby establishing a traffic priority mapping relationship between BACnet / IP and TSN.

[0013] Different scheduling methods are used for BACnet / IP's periodic and non-periodic traffic, combined with TSN's refined priority management capabilities to maximize the real-time transmission and reliability of data streams. Through this integrated scheduling solution, the system can significantly reduce latency in the BACnet / IP system, ensuring that key tasks are completed on time, thereby improving the performance and deterministic delivery capabilities of the entire building and industrial automation system.

[0014] The present invention can give priority to the transmission of real-time periodic traffic without exceeding given bandwidth resources, and maximize the use of bandwidth and reduce delay, and can adapt to complex network data and dynamically adjust the scheduling scheme. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The overall structure diagram of a joint scheduling method of BACnet / IP and TSN network described in the present invention;

[0016] Figure 2 This is a non-periodic traffic instance scheduling diagram of a joint scheduling method for BACnet / IP and TSN networks described in the present invention. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] The present invention provides a joint scheduling method based on BACnet / IP and TSN network, which aims to maximize bandwidth utilization, minimize delay, and meet the service quality requirements of different priority flows by distinguishing BACnet / IP data frames into periodic data frames and non-periodic data frames and adopting different scheduling methods. Figure 1 As shown, the scheme includes the following steps:

[0019] S1. Build a joint system including BAcnet / IP network and TSN network.

[0020] S2. Obtain a BAcnet / IP data frame from the BAcnet / IP network, the BAcnet / IP data frame having been subjected to VLAN tagging processing at the data link layer.

[0021] Specifically, obtain the BAcnet / IP data frame from the BAcnet / IP network, the BAcnet / IP data frame contains information such as the destination address (DA) and the source address (SA). To ensure that the BAcnet / IP data frame can be transmitted in the TSN network, it is necessary to add VLAN tags to the BACnet / IP data frame at the data link layer, including: adding a 4-byte VLAN tag after the source MAC address of the BAcnet / IP data frame, filling different values ​​in the PCP field in the VLAN tag, using the VLAN tag to identify the priority of the BACnet / IP data frame, and corresponding to the traffic priority of the TSN data frame, thereby establishing a traffic priority mapping relationship between the BACnet / IP network and the TSN network. This method can enable the TSN switch to schedule BACnet / IP data frames normally without changing other protocols.

[0022] S3. Determine whether the BAcnet / IP data frame is periodic traffic based on its transmission characteristics.

[0023] Specifically, based on the transmission characteristics of the BACnet / IP data frame, determine whether the data frame is periodic traffic or non-periodic traffic. Periodic traffic has a stable transmission cycle, such as sensor data collected in a building automation system. Non-periodic traffic is usually event-driven, such as alarm information.

[0024] S4. If the BAcnet / IP data frame is non-periodic traffic, the periodic traffic is scheduled in the periodic queue corresponding to the BACnet / IP data frame according to the mapped traffic priority, using a periodic data scheduling method based on load adaptive priority.

[0025] Specifically, step S5 performs a periodic data scheduling method based on load adaptive priority, including:

[0026] S41. Calculate the continuous period T based on the period of all periodic traffic in the current BACnet / IP network cont and cycle period T cycle , which can be expressed as

[0027] T cont =gcd(T1, T2, ..., T n-1 , T n ) (1)

[0028] T cycle = lcm(T1, T2, ..., T n-1 , T n ) (2)

[0029] Wherein, the cycle period T cycleis the least common multiple of the periods of all periodic flows (lcm), the continuous period T cont is the greatest common divisor (gcd) of the periods of all periodic flows, and n represents the number of periodic flows.

[0030] S42. When the system is under high load, the priority weight of the periodic traffic is calculated, and the strategy is adjusted according to the priority weight, giving more scheduling opportunities to periodic traffic with high traffic priority, low period, and low tolerance time, while delaying the scheduling of periodic traffic with low traffic priority and large tolerance time when the system load is heavy. The priority weight calculation formula for each periodic traffic is:

[0031]

[0032] Among them, W i represents the priority weight of the i-th periodic traffic, P i represents the traffic priority of the i-th periodic traffic, D i represents the delay tolerance of the ith periodic flow, T i represents the period of the ith periodic traffic. Traffic priority P i With period T i and delay tolerance D i The shorter the period, the shorter the delay tolerance, and the higher the traffic priority of the periodic traffic, the greater the priority weight, and the system will prioritize scheduling of these periodic traffic.

[0033] S43. Active scheduling window allocation, dynamically adjust the time windows of different periodic flows according to the priority weight and network load. The time window size calculation formula for each periodic flow is:

[0034]

[0035] Where, ΔT i represents the time window size of the i-th periodic flow, W i represents the priority weight of the i-th periodic traffic, is the sum of the priority weights of all periodic traffic.

[0036] S44. Determine whether the periodic traffic is a tolerant periodic task. If so, calculate the latest scheduling time of the periodic traffic. The present invention further divides the periodic traffic into non-tolerant periodic tasks and tolerant periodic tasks according to whether the tolerant delay is greater than or equal to 0. For tolerant periodic tasks, a delay tolerance mechanism is established to allow the transmission delay of the tolerant periodic task to be extended to obtain a latest scheduling time. If the i-th periodic traffic is a tolerant periodic task i, its latest scheduling time can be

[0037] Ti，D =T i +D i (5)

[0038] T i，D Indicates the latest scheduling time of the tolerated periodic task i.

[0039] S45. In order to ensure that all periodic flows can be within a cycle period T cycle The number of times each periodic flow is scheduled in a cycle is calculated.

[0040] If the i-th periodic traffic is a non-tolerant periodic task, the number of times the non-tolerant periodic task is scheduled in the cycle is for

[0041]

[0042] If the i-th periodic flow is a tolerant periodic task, the number of times the tolerant periodic task is scheduled within the cycle is for

[0043]

[0044] S46. Scheduling the periodic traffic according to the scheduling rules, including:

[0045] At least one periodic flow is scheduled in a continuous period;

[0046] Each periodic flow is scheduled within a cycle according to the period and the number of times it is scheduled;

[0047] Schedule periodic traffic based on priority weights within consecutive periods.

[0048] Each periodic flow is scheduled at least once in a cycle.

[0049] Specifically, the periodic data scheduling method based on load adaptive priority improves the real-time performance and resource utilization of task scheduling by building a reasonable scheduling cycle model, dynamic priority adjustment and flexible scheduling window allocation. Combined with the delay tolerance mechanism, low-priority tasks will not affect the execution of high-priority tasks under high load.

[0050] In one embodiment, it is assumed that there are multiple periodic flows in the BACnet / IP network. Specific information can be found in Table 1:

[0051] Table 1 Periodic data flow

[0052] Periodic traffic <![CDATA[Period T i (us)]]> <![CDATA[Traffic priority P i > <![CDATA[Delay Tolerant D i (us)]]> <![CDATA[r1]]> 200 3 0 <![CDATA[r2]]> 500 4 0 <![CDATA[r3]]> 100 2 0 <![CDATA[r4]]> 300 5 0 <![CDATA[r5]]> 600 2 100

[0053] There are five types of periodic traffic with different periods, of which r1-r4 are all non-tolerant periodic tasks, and r5 is a tolerant periodic task.

[0054] Then, the cycle period T can be calculated based on the period of all periodic flows using formulas (1) and (2): cycle , as shown below:

[0055] T cont =lcm{200,500,100,300,600}=100us

[0056] T cycle =lcm{200,500,100,300,600}=3000us

[0057] According to formula (3), the priority weight W of each periodic flow is calculated i :

[0058]

[0059] The periodic traffic with higher priority weight will be scheduled first and occupy more scheduled times in the scheduling cycle.

[0060] According to formula (4), the time window size of each periodic flow is calculated as:

[0061]

[0062] According to formula (5), the latest scheduling time T of the delay-tolerant task is calculated 5，D :

[0063] T 5，D =600+100=700

[0064] According to formulas (6) and (7), the scheduling times of various periodic tasks can be obtained:

[0065]

[0066] Thus, the specific scheduling conditions of the periodic traffic r1-r5 in the periodic time period of each continuous period are obtained as shown in Table 2, where D1 refers to the periodic traffic r5.

[0067] Table 2 Scheduling of periodic periods

[0068]

[0069] The entire cycle is divided into multiple continuous cycles, and each periodic flow is scheduled in different continuous cycles according to the multiples of its own cycle, wherein the tolerance period task is scheduled in different continuous cycles according to the multiples of the latest scheduling time. Furthermore, in this embodiment, the cycle is 3000us, and the continuous cycle is 100us, so the entire cycle can be divided into 30 continuous cycles. Since the cycle of periodic flow r3 is 100us, it will be scheduled in each continuous cycle, so its number of scheduling times is 30. The cycles of periodic flows r1, r3, and r4 meet the multiple relationship of 600, so at 600us, periodic flows r1, r3, and r4 will all be scheduled. At this time, scheduling is performed according to the priority weight. The larger the priority weight, the higher the priority scheduling. The time window is the total scheduling time of each periodic flow.

[0070] S5. If the BAcnet / IP data frame is aperiodic traffic, the BAcnet / IP data frame is allocated to the corresponding aperiodic queue according to the traffic priority, and a dynamic adjustment strategy is used to implement the scheduling of aperiodic traffic.

[0071] Specifically, the present invention combines the real-time scheduling theory of Liu and Layland, Amdahl's law and the knapsack problem, and proposes a dynamic adjustment strategy to maximize bandwidth utilization and minimize total delay through dynamic priority adjustment.

[0072] The dynamic adjustment strategy performs multiple rounds of scheduling by dynamically adjusting the non-periodic queue priority, in which the system state is defined to represent the parameter state at the beginning of each round of scheduling, as shown in Table 3.

[0073] Table 3 Parameter status

[0074]

[0075] It is expressed as

[0076] S t = {B remain , L 11 , …L NM , D1,…,D N , P 1，t ,…,P N，t , Q1,…,Q N} (5)

[0077] Among them, S t represents the system status of the tth round of scheduling, Bremain represents the current remaining bandwidth of the system, and L nm represents the frame length of the m=1, 2, ..., M non-periodic traffic in the n=1, 2, ..., N non-periodic queues, D nrepresents the cumulative delay corresponding to the nth non-periodic queue, P n，t represents the priority of the nth non-periodic queue at the beginning of the tth round of scheduling, Q n Indicates the untransmitted data in the nth non-periodic queue; N indicates the number of non-periodic queues, and M indicates the number of non-periodic traffic in the non-periodic queue.

[0078] The dynamic adjustment strategy proposed in the present invention is based on the earliest deadline first scheduling algorithm in the task scheduling theory of Liu and Layland. Firstly, the priority value formula is defined in combination with the frame length, accumulated delay and the amount of remaining untransmitted data, and a dynamic priority strategy similar to EDF is adopted.

[0079] The priority is defined as:

[0080]

[0081] Among them, α, β, and γ represent the delay weight, frame length weight, and remaining data weight respectively. The specific values ​​need to be set according to the actual situation. Each time the queue priority is updated, each non-periodic queue selects the frame length of the current first non-periodic traffic for calculation.

[0082] This formula draws on the concept of "urgency" in the EDF strategy proposed by Liu and Layland. When the delay is large (i.e., D n Large), the priority should be increased, and when the frame is longer (i.e. L nm In order not to block bandwidth allocation, the priority should be lowered. n The queue priority should be increased so that the transfer can be completed as soon as possible.

[0083] Because the priority value range of the TSN data frame is limited to 0 to 7, it is rounded up and limited to the range:

[0084] P n，t+1 =min(7,max(0,round(P n，t ))) (7)

[0085] Combined with Amdahl's law, the present invention optimizes the transmission efficiency of frames. In each scheduling, frames that have a greater improvement in the overall performance of the system should be preferentially selected for transmission. For example, transmitting short frames can quickly release bandwidth, thereby improving the bandwidth utilization of the overall system.

[0086] Based on the idea of ​​the knapsack problem, bandwidth allocation can be seen as the limitation of the knapsack capacity (i.e., bandwidth), and the transmitted data frames are the items we want to put into the knapsack. We hope to transmit as much high-priority data as possible in the limited bandwidth. The bandwidth allocation formula is:

[0087]

[0088] Among them B allocated is the bandwidth allocated in the current round, I n Is a binary variable indicating whether the non-periodic queue is selected. n is 1 if the value is true, otherwise it is 0.

[0089] Specifically, the dynamic adjustment strategy is used to implement the scheduling of non-periodic traffic, including:

[0090] S51. Obtain the system status of the tth round of scheduling, and use the priority value formula to calculate and update the priority of each non-periodic queue;

[0091] S52. Schedule a non-periodic flow from each non-periodic queue in order from largest to smallest priority. If the priorities are the same, schedule them in ascending order according to the size of the untransmitted data in the non-periodic queues.

[0092] S53. Determine whether the scheduling is completed. If not, set t=t+1 and return to step S51.

[0093] In one embodiment, it is assumed that there are multiple types of non-periodic traffic in the BACnet / IP network, and it is assumed that the bandwidth that can be transmitted each time during the non-periodic time is 600 types, that is, the remaining bandwidth B remain There are 600 bytes left. According to the priority mapping relationship, it is allocated to the corresponding priority queue. For specific information, see Table 4:

[0094] Table 4 Non-periodic queue data flow

[0095] Non-periodic queue Frame length Initial delay Queue priority No data transferred <![CDATA[Queue1]]> 80,100,120 50 3 300 <![CDATA[Queue2]]> 120,130,180 40 2 430 <![CDATA[Queue3]]> 140,160,220 30 4 520

[0096] During the first round of scheduling, the system state S1 is expressed as:

[0097] S1={600,80,100,120,...120,140,160,220,50,40,30,3,2,4,300,430,520}

[0098] The queue priorities of the non-periodic queues Queue1, Queue2, and Queue3 can be calculated by equations (6) and (7) (assuming that α=0.5, β=0.3, and y=0.2).

[0099] P 1，2 =min(7,max(0,round(P 1，1 )))=4

[0100] P 2，2 =min(7,max(0,round(P2，1 )))=2

[0101] P 3，2 =min(7,max(0,round(P 3，1 )))=4

[0102] The non-periodic queues Queue 1 and Queue 3 have the same queue priority, so non-periodic queue Queue 1 is scheduled first. In this round of scheduling, non-periodic queue Queue 1 is allocated 80 bytes, non-periodic queue Queue 3 is allocated 140 bytes, and non-periodic queue Queue 2 is allocated 120 bytes.

[0103] In the second round of scheduling, the system state S2 is updated to:

[0104] S2={600, 100, 120, 130, 180, 160, 220, 50, 40, 30, 4, 2, 4, 220, 310, 380}

[0105] The queue priorities of the non-periodic queues Queue1, Queue2, and Queue3 are updated to

[0106] P 1，3 =min(7,max(0,round(P 1，2 )))=6

[0107] P 2，3 =min(7,max(0,round(P 2，2 )))=2

[0108] P 3，3 =min(7,max(0,round(P 3，2 )))=4

[0109] In this round of scheduling, the non-periodic queue Queue1 is allocated 100 bytes, the non-periodic queue Queue3 is allocated 130 bytes, and the non-periodic queue Queue2 is allocated 160 bytes.

[0110] In the third round of scheduling, the system state S3 is updated to:

[0111] S3={600,120,180,220,50,40,30,6,2,4,120,180,220}

[0112] The queue priorities of the non-periodic queues Queue1, Queue2, and Queue3 are updated to

[0113] P 1，4 =min(7,max(0,round(P 1，3)))=6

[0114] P 2，4 =min(7,max(0,round(P 2，3 )))=2

[0115] P 3，4 =min(7,max(0,round(P 3，3 )))=4

[0116] In this round of scheduling, the non-periodic queue Queue1 is allocated 120 bytes, the non-periodic queue Queue3 is allocated 180 bytes, and the non-periodic queue Queue2 is allocated 220 bytes. At this point, the scheduling is complete. Through the dynamic adjustment of queue priorities and the reasonable allocation of bandwidth, after several rounds of scheduling, all data frames are transmitted. Figure 2 As shown in Figure 2, the scheduling process optimizes the total delay and allocates the bandwidth reasonably.

[0117] In the present invention, unless otherwise clearly stipulated and limited, the terms such as "installation", "setting", "connection", "fixation" and "rotation" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0118] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A joint scheduling method based on BACnet / IP and TSN network, characterized in that: The following steps are involved: S1. Build a joint system including BAcnet / IP network and TSN network; S2. Obtain a BAcnet / IP data frame from the BAcnet / IP network. The BAcnet / IP data frame is subjected to VLAN tagging at the data link layer to identify the traffic priority of the BACnet / IP data frame in the TSN network. S3. Determine whether the BAcnet / IP data frame is periodic traffic based on its transmission characteristics; S4. If the BACnet / IP data frame is periodic traffic, the BACnet / IP data frame is allocated to the corresponding periodic queue according to the traffic priority, and the periodic traffic is scheduled using a periodic data scheduling method based on load adaptive priority; S5. If the BACnet / IP data frame is aperiodic traffic, the BACnet / IP data frame is allocated to the corresponding aperiodic queue according to the traffic priority, and the scheduling of the aperiodic traffic is realized by using a dynamic priority adjustment strategy.

2. A joint scheduling method based on BACnet / IP and TSN network according to claim 1, characterized in that: The VLAN tag is added to the BAcnet / IP data frame at the data link layer, including: adding a 4-byte VLAN tag after the source MAC address of the BAcnet / IP data frame, filling the PCP field in the VLAN tag with different values, and then establishing a traffic priority mapping relationship between the BACnet / IP network and the TSN network.

3. The joint scheduling method based on BACnet / IP and TSN network according to claim 1, characterized in that: Step S4 executes the periodic data scheduling method based on load adaptive priority, including: S41. Calculate the continuous period T based on the period of all periodic traffic in the current BACnet / IP network cont and cycle period T cycle ; S42. Calculate the priority weight of each periodic traffic based on traffic priority, cycle and delay tolerance; S43 dynamically calculates the time window for each periodic flow according to the priority weight and network load; S44. Determine whether the periodic traffic is a tolerant periodic task, and if so, calculate the latest scheduling time of the periodic traffic; S45. Calculate the number of times each periodic flow is scheduled within a cycle; S46. Scheduling the periodic traffic according to the scheduling rules, including: At least one periodic flow is scheduled in a continuous period; Each periodic flow is scheduled within a cycle according to the period and the number of times it is scheduled; Schedule periodic traffic based on priority weights within consecutive periods.

4. The joint scheduling method based on BACnet / IP and TSN network according to claim 3 is characterized in that: The priority weight W of the i-th periodic flow i Expressed as Among them, P i represents the traffic priority of the i-th periodic traffic, D i represents the delay tolerance of the ith periodic flow, T i represents the period of the i-th periodic flow; The time window size of the i-th periodic flow △T i Expressed as Where n represents the number of periodic flows.

5. The joint scheduling method based on BACnet / IP and TSN network according to claim 3 is characterized in that: Step S45 calculates the number of times each periodic flow is scheduled in a cycle, including: If the i-th periodic traffic is a non-tolerant periodic task, the number of times the non-tolerant periodic task is scheduled in the cycle is for If the i-th periodic flow is a tolerant periodic task, the number of times the tolerant periodic task is scheduled within the cycle is for Among them, T i represents the period of the ith periodic flow, T i,D It indicates the latest scheduling time of the tolerated periodic task i, and round() indicates the rounding down operation.

6. The joint scheduling method based on BACnet / IP and TSN network according to claim 1, characterized in that: The dynamic adjustment strategy performs multiple rounds of scheduling by dynamically adjusting the priority of the non-periodic queue. The system state is defined to represent the parameter state at the beginning of each round of scheduling, which is expressed as S t ={B remain ,L 11 ,…L NM ,D1,…,D N ,P 1,t ,…,P N,t ,Q1,…,Q N } Among them, S t represents the system status of the tth round of scheduling, Bremain represents the current remaining bandwidth of the system, and L nm represents the frame length of the m=1,2,…,M non-periodic traffic in the n=1,2,…,N non-periodic queues, D n represents the cumulative delay corresponding to the nth non-periodic queue, P n,t represents the priority of the nth non-periodic queue at the beginning of the tth round of scheduling, Q n Indicates the untransmitted data in the nth non-periodic queue; N indicates the number of non-periodic queues, and M indicates the number of non-periodic traffic in the non-periodic queue.

7. A joint scheduling method based on BACnet / IP and TSN network according to claim 6, characterized in that: The dynamic adjustment strategy used to implement non-periodic traffic scheduling includes: S51. Obtain the system status of the tth round of scheduling, and use the priority value formula to calculate and update the queue priority of each non-periodic queue; S52. Schedule a non-periodic flow from each non-periodic queue in descending order according to the queue priority; if the priorities are the same, schedule the non-periodic queue in ascending order according to the size of the untransmitted data; S53. Determine whether the scheduling is completed. If not, set t=t+1 and return to step S51.

8. The joint scheduling method based on BACnet / IP and TSN network according to claim 7, characterized in that: The priority value formula is expressed as P n,t+1 =min(7,max(0,round(P n,t ))) Among them, α, β, and γ represent the delay weight, frame length weight, and remaining data amount weight, respectively.

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