Industrial control system and communication method thereof

Abstract

According to the industrial control system and the communication method thereof provided by the invention, the communication system comprising the passive optical network and the bus expansion module is adopted, transmission links from the master rack to the plurality of slave racks can be realized, a plurality of communication modules do not need to be adopted, the cost of the industrial control system is reduced, meanwhile, the passive optical network forwards signals, the transmission efficiency is high, and the communication efficiency is high. The problem of large time delay caused by one-by-one forwarding of communication modules is avoided, the communication efficiency is improved, the cost is reduced, the system stability is improved, and a more efficient, reliable and economical industrial control system is realized.

Description

Technical Field

[0001] The present invention belongs to the field of communication technology, and more specifically, relates to an industrial control system and a communication method thereof. Background Art

[0002] In industrial control systems, the controller module plays a core role. It periodically collects real-time data from the I / O module, performs necessary operations on the data, and then periodically outputs the processing results back to the I / O module to achieve real-time control and monitoring of the system. With the development of industrial automation, the application scenarios of remote IO are increasing, which puts higher requirements on the communication efficiency and reliability of the control system. At present, the communication network inside the industrial control station is mainly built through the local IO bus and the extended IO bus to support complex IO device connections and data transmission.

[0003] At present, the architecture in which the main rack is connected to the remote rack through the communication module is adopted. The communication module on any rack is not only connected to the I / O module of the same rack through the local IO bus, but also communicates with the remote rack through an efficient data transmission protocol, forming a more flexible and efficient bus-type connection network.

[0004] However, more communication modules need to be configured, resulting in higher costs for the industrial control system, and there is a large delay in data forwarding by the communication modules. Summary of the invention

[0005] In view of this, an object of the present invention is to provide an industrial control system and a communication method thereof, which are used to improve communication efficiency, reduce costs and improve system stability, so as to realize a more efficient, reliable and economical industrial control system.

[0006] The first aspect of the present application discloses an industrial control system, comprising: a main rack, a communication system and a remote rack; the communication system comprises: a passive optical network and a bus expansion module;

[0007] The main frame is connected to the first end of the passive optical network through a first bus expansion module;

[0008] The N second ends of the passive optical network correspond one-to-one to the N second bus extension modules, and each second end in the passive optical network is connected to the first end of the second bus extension module corresponding to each second end;

[0009] The second end of the second bus expansion module is connected to a different remote rack;

[0010] The main frame and the first bus expansion module are connected by a BLVDS backplane;

[0011] The remote rack and the second bus expansion module are connected by a BLVDS backplane;

[0012] The main rack, the passive optical network, the first bus extension module, the second bus extension module and the remote rack form a star network structure.

[0013] Optionally, the main frame includes a communication module, a controller and an I / O module;

[0014] The communication module, the controller and the I / O module are all connected to a local IO bus;

[0015] The controller serves as the core of the IO bus communication network of the industrial control system; each bus expansion module serves as a communication unit of the IO bus communication network of the industrial control system.

[0016] Optionally, the passive optical network includes: an optical fiber and an optical splitter;

[0017] One end of the optical fiber is connected to the first bus extension module;

[0018] The other end of the optical fiber is connected to one end of the optical splitter;

[0019] The N second ends of the optical splitter serve as the N second ends of the passive optical network.

[0020] Optionally, the number of remote racks is 15.

[0021] Alternatively, the number of the communication systems is 2 or 1.

[0022] Optionally, 8B / 10B balanced encoding is used to encode the IO bus signal.

[0023] Optionally, the bus extension module includes: a BLVDS interface, an FPGA, and an optical interface module supporting EPON / GPON;

[0024] The BLVDS interface is connected to the corresponding BLVDS backplane;

[0025] The optical interface module is connected to the passive optical network;

[0026] The FPGA is used to realize signal forwarding and control the optical interface module.

[0027] A second aspect of the present application discloses a communication method for an industrial control system, comprising:

[0028] The industrial control system adopts a token scheduling method to control the flow scheduling of uplink data in the passive optical network.

[0029] Optionally, the industrial control system adopts a token scheduling method to control the flow scheduling of uplink data in the passive optical network, including:

[0030] Using broadcast technology, the target data of the main rack is sent to each remote rack through a transmission link; the target data includes the address of the target remote rack;

[0031] Each remote rack determines whether its own address is consistent with the address of the target remote rack in the received target data;

[0032] If so, the target remote rack sends response data to the host rack via the transmission link.

[0033] Optionally, also include:

[0034] The link scheduler in the bus extension module monitors the link status in real time. When the link status is abnormal, the link scheduler retracts the target data.

[0035] Optionally, the working process of the optical interface module of the bus extension module in the industrial control system is:

[0036] In the uplink direction, after the optical interface module completes the reception of a data packet, it waits for the minimum interval time, the optical interface module performs a reset operation, and the detection signal of the optical interface module is pulled low; when the detection signal of the optical interface module is pulled high, the optical interface module receives a new data packet; wherein the minimum interval time is the time required for the controller to send a token to the I / O module to reply to the data;

[0037] In the downlink direction, the optical module adopts the continuous working mode. After the optical module completes sending a data packet, it continues to send the scrambled signal.

[0038] It can be seen from the above technical solution that an industrial control system provided by the present invention adopts a communication system including a passive optical network and a bus expansion module to realize a transmission link from a main rack to multiple remote racks, without the need to use multiple communication modules, thereby reducing the cost of the industrial control system. At the same time, the passive optical network forwards the signal with high transmission efficiency, avoiding the problem of large delay caused by forwarding one by one using communication modules, thereby improving communication efficiency, reducing costs and improving system stability, so as to realize a more efficient, reliable and economical industrial control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 is a schematic diagram of an industrial control system provided by an embodiment of the present invention;

[0041] Figure 2 is a schematic diagram of another industrial control system provided by an embodiment of the present invention;

[0042] Figure 3 It is a flowchart of token scheduling involved in another industrial control system provided by an embodiment of the present invention;

[0043] Figure 4 This is a working timing diagram of an optical module involved in another industrial control system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0045] In the present application, the term "comprise", "include" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the sentence "comprise one ..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. In addition, the terms "first", "second", "third", "fourth", etc. (if present) in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable in appropriate circumstances, so that the embodiments of the present application described here can be implemented in an order other than those illustrated or described here, for example.

[0046] The embodiment of the present application provides an industrial control system for solving the problem in the prior art that a large number of communication modules need to be configured, resulting in a high cost of the industrial control system and a large delay in forwarding data by the communication modules.

[0047] See also Figure 1 The industrial control system includes: a main rack, a communication system and a remote rack; the communication system includes: a passive optical network and a bus expansion module.

[0048] The main rack is connected via the first bus expansion module (such as Figure 1 The bus expansion module A shown in FIG. 1 is connected to a passive optical network (including Figure 1 The first end of the optical fiber and optical splitter shown.

[0049] Specifically, the main frame is connected to the BLVDS interface of the first bus extension module; and the optical port of the first bus extension module is connected to the first end of the passive optical network.

[0050] The main frame and the first bus expansion module are connected by a BLVDS backplane.

[0051] Specifically, the main frame is connected to one end of the BLVDS baseboard, and the BLVDS interface of the first bus extension module is connected to the other end of the BLVDS baseboard.

[0052] It should be noted that the low voltage differential signal is transmitted between the main frame and the first bus expansion module; the low voltage differential signal adopts differential transmission technology, that is, signals with the same amplitude and opposite phases are transmitted simultaneously on two signal lines. The receiving end determines the logical state sent by the sending end by comparing the difference between the two signals.

[0053] Low-voltage differential signals have strong anti-interference capabilities. Since interference noise is generally equal and loaded onto two signal lines at the same time, and the receiver only cares about the difference between the two signals, external common-mode noise can be completely offset.

[0054] Low voltage differential signaling can effectively suppress electromagnetic interference (EMI). Since the two wires are close together and the signal amplitudes are equal, the amplitudes of the coupled electromagnetic fields between the two wires and the ground wire are also equal, and their signal polarities are opposite, so the magnetic lines of force will cancel each other out, reducing electromagnetic radiation.

[0055] Low voltage differential signal has the advantage of accurate timing positioning. The receiving end of the low voltage differential signal is the point where the difference in the signal amplitude on the two lines changes positively or negatively, which is used as the point for judging the logic 0 / 1 change. This transmission method is more suitable for low amplitude signals and is less affected by the ratio of threshold voltage to signal amplitude voltage.

[0056] Low voltage differential signals are often used in high-speed data transmission interfaces. These interfaces have the advantages of low power consumption, low noise, high anti-interference ability and high speed, and are suitable for point-to-point or multi-point communication.

[0057] The N second terminals of the passive optical network and the N second bus expansion modules (such as Figure 1 The second bus extension modules B, C, and D) shown in the figure correspond one to one, and each second end in the passive optical network is connected to the first end of the second bus extension module corresponding to each other.

[0058] Specifically, the first second end of the passive optical network is connected to the first end of the first second bus extension module; the second second end of the passive optical network is connected to the first end of the second second bus extension module; and so on, the Nth second end of the passive optical network is connected to the first end of the Nth second bus extension module.

[0059] The second end of the second bus expansion module is connected to a different remote chassis.

[0060] Specifically, the N second bus expansion modules correspond to the N remote racks one by one, and the second end of each second bus expansion module is connected to the corresponding remote rack.

[0061] More specifically, the second end of the first second bus expansion module is connected to the first remote rack; the second end of the second second bus expansion module is connected to the second remote rack; and so on, the second end of the Nth second bus expansion module is connected to the Nth remote rack. Of course, it is not excluded that the second end of one second bus expansion module is connected to at least two remote racks, which will not be described here one by one, depending on the actual situation, and all are within the protection scope of this application.

[0062] Each remote chassis is a slave chassis.

[0063] The remote rack and the second bus expansion module are connected via a BLVDS backplane.

[0064] Specifically, the remote rack is connected to one end of the BLVDS backplane, and the BLVDS interface (second end) of the second bus expansion module is connected to the other end of the BLVDS backplane. Low voltage differential signals are transmitted between the remote rack and the second bus expansion module.

[0065] The main frame, the passive optical network, the first bus extension module, the second bus extension module and the remote frame form a star network structure.

[0066] In other words, a point-to-multipoint communication network is realized.

[0067] Each node (such as a remote rack) in a star network structure is connected to a central node (such as a main rack) through an independent link (such as an optical fiber). This structure ensures that the failure of a single node will not affect the operation of the entire network, thereby improving the reliability of the network. As an important component of the network, the passive optical network uses all-optical fiber transmission, which has the characteristics of high bandwidth, long transmission distance and strong anti-interference ability, further enhancing the reliability of the network.

[0068] The star network structure is easy to expand and maintain. When a new node needs to be added, it is only necessary to connect the new node to the main frame through the bus expansion module. Passive optical fiber network technology also supports flexible bandwidth allocation and dynamic network access, and can provide customized services according to the needs of different users.

[0069] Compared with the bus structure, the star network structure has a shorter data transmission path, reducing the delay and loss of data transmission.

[0070] Passive optical fiber network technology uses broadcast mode for downstream and time division multiple access mode for upstream, which can efficiently utilize network resources and improve network throughput.

[0071] In this embodiment, a communication system including a passive optical network and a bus expansion module is used to realize a transmission link from a main rack to multiple remote racks, without the need to use multiple communication modules, thereby reducing the cost of the industrial control system. At the same time, the passive optical network forwards the signal with high transmission efficiency, avoiding the problem of long delay caused by forwarding one by one using communication modules, thereby improving communication efficiency, reducing costs and improving system stability, so as to realize a more efficient, reliable and economical industrial control system.

[0072] Optionally, the main frame includes a communication module, a controller and an I / O module.

[0073] Communication modules, controllers and I / O modules are all connected to the local IO bus.

[0074] The controller serves as the core of the IO bus communication network of the industrial control system; each bus expansion module serves as a communication unit of the IO bus communication network of the industrial control system.

[0075] The main rack is a highly integrated component collection that includes communication modules, controllers, and I / O modules. These modules are connected to the local IO bus to form an efficient and collaborative system.

[0076] The controller undoubtedly plays a pivotal role. It is not only the central brain of the industrial control system IO bus communication network, responsible for the scheduling and management of the entire network, but also the key to ensure the stable operation of the system and efficient data processing.

[0077] At the same time, each bus expansion module also plays an indispensable role. It is like a bridge and bond in the communication network, connecting each node closely to ensure the accurate and fast transmission of information. As the communication unit of the industrial control system IO bus communication network, the bus expansion module provides a solid foundation for the expansion and upgrade of the system.

[0078] In other words, the main frame builds a powerful, flexible and scalable industrial control system IO bus communication network by integrating communication modules, controllers, I / O modules and bus expansion modules.

[0079] In this embodiment, the controller of the main frame is used as the core of the IO bus communication network, and the bus expansion module is used as a communication unit to forward the IO bus. The network communication based on this protocol, that is, broadcast mode downlink and time division multiple access mode uplink, has the characteristics of low cost, low latency and high reliability.

[0080] Optionally, the passive optical network includes: optical fiber and an optical splitter.

[0081] One end of the optical fiber is connected to the first bus extension module; the other end of the optical fiber is connected to one end of the optical splitter.

[0082] Specifically, one end of the optical fiber is closely connected to the first bus expansion module, ensuring efficient transmission of the signal; and the other end of the optical fiber is seamlessly connected to one end of the optical splitter, further extending the coverage of the network.

[0083] The N second ends of the optical splitter serve as the N second ends of the passive optical network.

[0084] As a key node in the network, the optical splitter has N second ports, which serve as N output ports of the passive optical network to provide access services for multiple terminal devices.

[0085] It is worth noting that the connection medium between the optical splitter and the first bus extension module is optical fiber. This connection method not only ensures the high speed and stability of data transmission, but also greatly improves the reliability and flexibility of the entire passive optical network.

[0086] Optionally, the number of remote racks is 15.

[0087] That is to say, the total number of remote racks and main racks is 16, and communication among 16 racks can be achieved.

[0088] Optionally, 8B / 10B balanced encoding is used to encode the IO bus signal.

[0089] Using 8B / 10B balanced encoding to encode IO bus signals can achieve DC balance and signal quality, clock recovery and data synchronization, error detection and data verification, as well as coding efficiency and compatibility. Specifically:

[0090] DC balance and signal quality. Ensure DC balance: 8B / 10B coding ensures that the number of 0s and 1s in the encoded data is roughly equal through carefully designed mapping rules, avoiding long strings of 0s or 1s. This DC balance feature helps reduce the DC offset of the signal during transmission, reduces signal distortion, and thus improves signal quality. Optimize signal spectrum: 8B / 10B coding can transfer energy from low frequency bands to high frequency bands, similar to the effect of a high-pass filter. This helps to keep the frequency domain curve flat after the transmission channel, effectively alleviates inter-symbol interference (ISI), and improves the reliability of data transmission.

[0091] Clock recovery and data synchronization. Facilitates clock recovery: 8B / 10B encoding ensures that there are enough edge transitions in the data stream, which provide the basis for clock recovery at the receiving end. The receiving end can recover the clock signal by detecting these edge transitions, thereby achieving synchronization of data transmission. No external clock is required: Since 8B / 10B encoding can embed clock information, no additional distributed clock is required during the transmission process. It avoids problems such as clock skew and flight time in parallel transmission, simplifies system design, and improves the rate and stability of data transmission.

[0092] Error detection and data verification. Error detection capability: There are 1024 possible code patterns for 10-bit data after 8B / 10B encoding, but only 536 of them are valid code words. The receiving end can determine whether the transmission is wrong by checking whether the received code word is in the valid code word list. This error detection capability helps to promptly detect and correct errors in the transmission process. Increase signal verification: 8B / 10B encoding also provides additional check bits, which can be used for data alignment and control command transmission. By setting and checking the check bits, the accuracy and reliability of data transmission can be further improved.

[0093] Coding efficiency and compatibility. Coding efficiency: Although 8B / 10B coding introduces 20% additional overhead (encoding 8-bit data as 10-bit data), its advantages in ensuring DC balance, clock recovery, and error detection make this overhead worthwhile. In addition, through clever coding design, 8B / 10B coding can also improve data transmission efficiency to a certain extent. Wide compatibility: 8B / 10B coding has been widely used in high-speed serial interface fields such as Ethernet, fiber-optic communication, PCIe, SATA, USB3.0, etc. This wide compatibility makes 8B / 10B coding a standard coding method, which facilitates data transmission between different devices and systems.

[0094] In summary, using 8B / 10B balanced coding to encode IO bus signals has many advantages, including ensuring DC balance and signal quality, facilitating clock recovery and data synchronization, having error detection and data verification capabilities, as well as wide compatibility and certain coding efficiency. These advantages make 8B / 10B coding widely used and recognized in high-speed serial communications.

[0095] It should be noted that an optoelectronic transceiver system includes: a main device; a main optical module connected to the main device via a cable; a splitter connected to the main optical module; N slave optical modules connected to the splitter via optical fibers; N is a positive integer not less than 2; N slave devices connected to the N slave optical modules respectively via cables, and the slave devices achieve communication connection with the main device based on the slave optical modules, the splitter and the main optical module.

[0096] Compared with the present application, the optoelectronic transceiver system only has the connection mode of the optical network and the control of the optical transceiver, and does not have the scheduling mechanism of the data flow in the point-to-multipoint network. In addition, when transmitting electrical signals in the cable, bus protocols such as Profibus-DP, Modbus, and CAN are used. The transmission rate of these protocols is relatively low. The control method of the optical transceiver through the preset encoding method in this scheme is complex and difficult to control. It can meet the needs of low-speed data transmission, but is not suitable for high-speed data transmission applications.

[0097] That is, the present application adopts a token scheduling method with broadcast mode for downlink and time division multiple access mode for uplink to schedule the data flow in the point-to-multipoint network; and uses low-voltage differential signaling for transmission to improve transmission efficiency; and adopts 8B / 10B balanced encoding method, which is simple to control and meets the needs of high-speed data transmission.

[0098] Optionally, the number of communication systems is 2 (eg Figure 2 ) or 1 (as shown Figure 1 shown).

[0099] That is to say, there are two communication systems between the main rack and each remote rack to achieve communication redundancy.

[0100] In order to further improve the reliability of IO bus data communication, this communication system adopts a redundant configuration strategy, specifically implementing the redundant design of the data A / B network. This design means that the system has two independent data communication paths, namely network A and network B. Under normal circumstances, the two network paths can undertake data transmission tasks simultaneously or separately, thereby improving the efficiency and fault tolerance of data transmission.

[0101] More importantly, when a key component such as an optical module or optical splitter fails, the redundant configuration ensures that data communication between the controller and the remote I / O module will not be interrupted. The system will automatically switch to the backup network path to continue the data transmission task, thus effectively avoiding the risk of the entire communication system being paralyzed due to a single point of failure.

[0102] In summary, by adopting a redundant configuration strategy, this communication system not only improves the reliability of data communication, but also enhances the fault tolerance and stability of the system, providing a solid technical guarantee for various application scenarios.

[0103] Optionally, the bus extension module includes: a BLVDS interface, an FPGA, and an optical interface module supporting EPON / GPON.

[0104] The BLVDS interface is connected to its corresponding BLVDS backplane.

[0105] The optical interface module connects to the passive optical network.

[0106] FPGA is used to realize signal forwarding and control the optical interface module.

[0107] The IO bus network (including bus extension module + optical splitter + optical fiber) is a star network structure. One side of the bus extension module is connected to the rack through a cable, and the other side is connected to the passive optical network through its own optical interface module, and is connected to multiple bus extension modules to form a star structure. In the rack, the controller and IO, and IO and IO are interconnected through the BLVDS backplane bus. The first bus extension module is the root node of the passive optical network, and each second bus extension module is a terminal node of the passive optical network.

[0108] The bus extension module realizes the mutual conversion from BLVDS bus to passive optical network. The bus extension module supports at least 1 optical port (optical interface module) and at least 1 BLVDS interface. The optical port can use EPON / GPON optical transceiver. The bus extension module uses programmable logic chip FPGA to realize signal forwarding and control of optical transceiver.

[0109] In this network, the first bus extension module plays a key role as the root node of the passive optical network, while each second bus extension module serves as the terminal node of the passive optical network, jointly maintaining the stable operation of the network. The bus extension module not only has the ability to convert BLVDS bus signals into passive optical network signals, but also supports reverse conversion, thus achieving a perfect integration of the two networks. Each bus extension module is equipped with at least one optical port (i.e., optical interface module) and one BLVDS interface. The optical port can flexibly select EPON / GPON optical transceiver to meet the needs of different scenarios.

[0110] The core of the network is the bus expansion module, which uses the programmable logic chip FPGA to realize signal forwarding and precise control of optical transceivers. This design not only improves the transmission efficiency of the network, but also ensures the stability and reliability of the signal.

[0111] In addition, the signal transmission of the industrial control system is carried out simultaneously in the full-duplex BLVDS backplane bus and the passive optical network, supporting a fiber transmission distance of up to 20 km, greatly expanding the coverage of the network. At the same time, it can also support IO bus connections of up to 16 racks, providing strong support for the signal transmission of the industrial control system.

[0112] In order to enhance the compatibility of the bus extension module, the following scheme is designed: the first bus extension module cooperates with the GPON / EPON OLT optical transceiver to act as the root node of the network; while the second bus extension module cooperates with the GPON / EPON ONU optical transceiver to act as the terminal node of the network. To achieve this goal, I2C bus technology is integrated in the bus extension module to obtain the category information of the optical transceiver. By identifying the specific type of optical transceiver, accurate control strategies can be implemented for different types of optical transceivers. This design not only improves the flexibility of the system, but also ensures the perfect compatibility of the bus extension module with various optical transceivers.

[0113] Another embodiment of the present application provides a communication method for an industrial control system.

[0114] The communication method of the industrial control system comprises:

[0115] In industrial control systems, token scheduling is used to control the flow scheduling of uplink data in passive optical networks.

[0116] It should be noted that the token scheduling model is Figure 3 As shown, MasterLAS is the controller of the master rack; Slave1\2\3\n are all slave racks (remote racks), Token is the target data, and response is the response data.

[0117] That is, the main rack sends the target data to the slave rack, and the slave rack responds to the target data and sends data upward. It should be noted that only one slave rack needs to send data upward in each period.

[0118] Token scheduling is an access control method based on token passing, which ensures that only one device (slave rack) can send data at any time, thus avoiding data conflicts. In a token scheduling system, each device is assigned a unique token, which is passed around the network. Only the device holding the token can send data, and after the transmission is completed, the token is passed to the next device.

[0119] Token allocation: In the upstream data flow, each remote chassis or upstream channel is assigned a unique token. These tokens are passed in the network according to a predetermined order or rule.

[0120] Data transmission: Only the remote rack holding the token can send upstream data streams. After the transmission is completed, the device passes the token to the next remote rack.

[0121] Conflict avoidance: Since only one remote rack holds the token and sends data at any time, data conflicts can be avoided. This mechanism ensures the stability and reliability of the upstream data flow.

[0122] Token recovery and reuse: After a token is passed through the network, it can be returned to the starting point for recovery and reuse. This ensures the continuous operation of the token scheduling system.

[0123] In the application of uplink data flow time-sharing scheduling, token scheduling can be implemented in the following ways:

[0124] Network design: Design a network architecture that supports token scheduling, including remote racks, uplink channels, token passing mechanisms, etc.

[0125] Token Allocation Algorithm: Develop a token allocation algorithm to ensure that each remote rack is assigned a unique token and delivered according to a predetermined order or rule.

[0126] Data transmission protocol: Develop a data transmission protocol that specifies the format, rate, error detection and correction mechanisms for data transmission.

[0127] Network monitoring and management: Implement network monitoring and management functions, including token status monitoring, data transmission status monitoring, fault detection and recovery, etc.

[0128] In summary, the token scheduling method can effectively realize the time-sharing scheduling of uplink data flow and avoid uplink data conflicts. This method has broad application prospects in many fields, such as communication networks, industrial control systems, etc.

[0129] In this embodiment, token scheduling is used to schedule the flow of uplink data in the passive optical network, ensuring that only one remote rack sends data at any time. The token scheduling method can effectively avoid data conflicts. In addition, since the token is circulated in the network, each remote rack has the opportunity to send data, thereby improving the utilization of the network. At the same time, it simplifies network management: the token scheduling method simplifies network management because the network administrator does not need to worry about data conflicts and transmission errors.

[0130] Optionally, a token scheduling method is used in the industrial control system to control the flow scheduling of the uplink data of the passive optical network, including:

[0131] The target data of the main rack is sent to each remote rack through the transmission link by using broadcast technology; the target data includes the address of the target remote rack;

[0132] Each remote rack determines whether its own address is consistent with the address of the target remote rack in the received target data;

[0133] If so, the target remote chassis sends response data to the main chassis via the transmission link.

[0134] It should be noted that the controller of the main rack can modify the address in the target data according to a preset order or rule, thereby realizing effective scheduling of each remote rack. Scheduling can be performed according to a scheduling table, or other methods can be used for scheduling. These methods will not be described here one by one, depending on the actual situation, and are all within the scope of protection of this application.

[0135] Specifically, when the controller needs to send target data to the I / O module of the remote rack connected to the target second bus expansion module, the controller sends the target data to the first bus expansion module through the BLVDS bus; the first bus expansion module forwards the target data received by its BLVDS port to its optical port and sends it to the passive optical network; the passive optical network sends it to all second bus expansion modules connected to the passive optical network in a broadcast form; the optical port of each second bus expansion module forwards to the BLVDS interface, and the BLVDS interface of each second bus expansion module sends it to the I / O module of the corresponding remote rack; the I / O module of the remote rack confirms whether to receive the data according to the destination address in the target data, if the address is consistent, it will be received, if the address is inconsistent, it will not be received. If the data is confirmed to be received, the remote rack prepares the data required by the main rack and sends the data to the main rack.

[0136] More specifically, when the controller needs to send data (such as target data) to the remote I / O module connected to the second bus expansion module B, the data is sent to the first bus expansion module A through the BLVDS bus. The first bus expansion module A forwards the signal received by its BLVDS port to its optical port to send it to the passive optical network, and sends it to all second bus expansion modules B, C, D, etc. connected to the optical splitter in a broadcast form. The signal is forwarded from the optical port of the second bus expansion module to the BLVDS interface and then sent to the I / O module on the remote rack. The I / O module confirms whether to receive the data according to the destination address of the data. When the remote I / O module connected to the bus expansion module B sends data, the data is sent to the second bus expansion module B through the BLVDS bus. The second bus expansion module B forwards the signal received by the BLVDS port to the passive optical network, and sends it to the first bus expansion module A through the passive optical network, and then sends it to the controller of the main rack via BLVDS.

[0137] It should be noted that the communication system network of the present invention adopts a point-to-multipoint star connection mode. In order for the bus extension module to perform data communication normally, it must be ensured that the optical module can perform photoelectric signal conversion normally during the point-to-multipoint communication process. The specific requirement is that the ONU optical module needs to turn off the sending enable in the idle state, and the receiving end of the ONU optical module will not cause the optical module to turn off reception or data reception abnormality due to the long idle time in the data communication. At the same time, the receiving end of the OLT optical module must be able to quickly recover the optical signals transmitted from different ONU optical modules, so the GPON / EPON optical module that supports the burst mode is selected. Therefore, it is necessary to control the GPON / EPON OLT and ONU optical modules. Among them, GPON / EPON: PON is a fiber optic access technology that uses passive devices to establish a network connection. GPON and EPON correspond to different passive optical network technical standards respectively. OLT: Optical Line Terminal, is a device at the network provider end. ONU: Optical Network Terminal, is a device at the user end.

[0138] The specific control methods are as follows:

[0139] It should be clear that the communication system network of the present invention adopts a point-to-multipoint star connection method. In order to ensure that the bus extension module can smoothly carry out data communication, it is necessary to ensure that the optical module can normally perform the conversion task of the photoelectric signal during the point-to-multipoint communication process. Specifically, this requires that the ONU optical module (the optical interface module in the first bus extension module) turns off its sending enable function in the idle state, and at the same time, the ONU optical module will not turn off the receiving function or data reception abnormality due to long-term idleness in data communication. In addition, the receiving end of the OLT optical module (the optical interface module in the second bus extension module) must be able to quickly recover the optical signals from different ONU optical modules. Therefore, a GPON / EPON optical module that supports burst mode is selected.

[0140] To achieve this goal, specific control of GPON / EPON OLT modules and GPON / EPON ONU optical modules is required. The specific control strategy is as follows:

[0141] In the uplink communication direction, the optical module at the transmitting end is a GPON / EPON ONU optical module, and the optical module at the receiving end is a GPON / EPON OLT optical module. Since the bandwidth allocation mechanism is not set in the system of the present invention, the controller of the main frame cannot predict the exact time when the I / O module in the remote module frame replies to the data packet, so it is difficult to directly control the burst mode of the optical module.

[0142] Therefore, the present invention adopts a control method for burst mode reception of a GPON / EPON optical transceiver; that is, the working process of the optical interface module of the bus expansion module in the industrial control system is:

[0143] In the upstream direction, after the optical interface module completes receiving a data packet, it waits for the minimum interval time, the optical interface module performs a reset operation, and the detection signal of the optical interface module is pulled low; when the detection signal of the optical interface module is pulled high, the optical interface module receives a new data packet; among which, the minimum interval time is the time required for the controller to send a token to the I / O module to reply data.

[0144] That is to say, when the optical module completes receiving a packet of data, it will wait for a minimum interval time. Then, the optical module will perform a reset operation, and its SD (signal detection) signal will be pulled low. Then, the optical module will wait for the SD signal to be pulled high again, which means that the optical transceiver has successfully received a new signal. Once the SD signal is detected to be high, the optical module will start to receive the next packet of data. Its working timing diagram is as follows Figure 4As shown in the figure, Optical Input Signal is the optical input signal; OLT RX Output is the output signal of the OLT optical module; RESET is the reset signal; SD Output is the output signal of the SD pin; that is, the SD (signal detection) signal; GUARD TIME is the protection time.

[0145] In the downlink direction, the optical module adopts the continuous working mode. After the optical module completes sending a data packet, it continues to send the scrambled signal.

[0146] In the downstream direction, the GPON / EPON OLT optical module acts as the transmitter, while the GPON / EPON ONU optical module acts as the receiver.

[0147] To ensure that the optical module at the receiving end can continuously and accurately receive data, both the transmitting end and the receiving end are set to continuous working mode. This means that the transmitting end will not only send optical signals during data packet transmission, but also continue to send the "0101010101" scrambling signal that matches the bit rate of the electrical signal after a data packet is sent, so as to maintain the continuity of the optical signal. In addition, the communication protocol of the present invention specifically uses the special code type K28.1 as the preamble code, aiming to achieve accurate alignment of bytes, thereby further improving the accuracy and stability of data transmission.

[0148] It should be noted that the upstream direction is that the remote rack sends data to the main rack; the downstream direction is that the main rack sends data to the remote rack.

[0149] Optionally, also include:

[0150] The link scheduler in the bus extension module monitors the link status in real time. When the link status is abnormal, the link scheduler retracts the target data.

[0151] The link status includes the existence of target data (token) loss. When at least one of the following situations occurs: target data loss or failure of the slave rack to respond within a preset time, an exception handling scheme is initiated. Moreover, when the maximum bus idle time is exceeded, the link scheduler reclaims the target data, that is, reclaims the token data.

[0152] The features recorded in the various embodiments in this specification can be replaced or combined with each other, and the same and similar parts between the various embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The system and system embodiments described above are only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

[0153] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0154] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An industrial control system, characterized in that: include: A main rack, a communication system and a remote rack; the communication system includes: a passive optical network and a bus expansion module; The main frame is connected to the first end of the passive optical network through a first bus expansion module; The N second ends of the passive optical network correspond one-to-one to the N second bus extension modules, and each second end in the passive optical network is connected to the first end of the second bus extension module corresponding to each second end; The second end of the second bus expansion module is connected to a different remote rack; The main frame and the first bus expansion module are connected by a BLVDS backplane; The remote rack and the second bus expansion module are connected by a BLVDS backplane; The main rack, the passive optical network, the first bus extension module, the second bus extension module and the remote rack form a star network structure.

2. The industrial control system according to claim 1, characterized in that: The main frame includes a communication module, a controller and an I / O module; The communication module, the controller and the I / O module are all connected to a local IO bus; The controller serves as the core of the IO bus communication network of the industrial control system; each bus expansion module serves as a communication unit of the IO bus communication network of the industrial control system.

3. The industrial control system according to claim 1, characterized in that: The passive optical network comprises: an optical fiber and an optical splitter; One end of the optical fiber is connected to the first bus extension module; The other end of the optical fiber is connected to one end of the optical splitter; The N second ends of the optical splitter serve as the N second ends of the passive optical network.

4. The industrial control system according to claim 1, characterized in that: The number of remote racks is 15; Alternatively, the number of the communication systems is 2 or 1.

5. The industrial control system according to claim 1, characterized in that: The IO bus signal is encoded using 8B / 10B balanced encoding.

6. The industrial control system according to claim 1, characterized in that: The bus extension module includes: a BLVDS interface, an FPGA and an optical interface module supporting EPON / GPON; The BLVDS interface is connected to the corresponding BLVDS backplane; The optical interface module is connected to the passive optical network; The FPGA is used to realize signal forwarding and control the optical interface module.

7. A communication method for an industrial control system, characterized in that: include: The industrial control system adopts a token scheduling method to control the flow scheduling of uplink data in the passive optical network.

8. The communication method of the industrial control system according to claim 7, characterized in that: The industrial control system adopts a token scheduling method to control the flow scheduling of uplink data in the passive optical network, including: Using broadcast technology, the target data of the main rack is sent to each remote rack through a transmission link; the target data includes the address of the target remote rack; Each remote rack determines whether its own address is consistent with the address of the target remote rack in the received target data; If so, the target remote rack sends response data to the host rack via the transmission link.

9. The communication method of the industrial control system according to claim 8, characterized in that: Also includes: The link scheduler in the bus extension module monitors the link status in real time. When the link status is abnormal, the link scheduler retracts the target data.

10. The communication method of the industrial control system according to claim 7, characterized in that: The working process of the optical interface module of the bus extension module in the industrial control system is as follows: In the uplink direction, after the optical interface module completes the reception of a data packet, it waits for the minimum interval time, the optical interface module performs a reset operation, and the detection signal of the optical interface module is pulled low; when the detection signal of the optical interface module is pulled high, the optical interface module receives a new data packet; wherein the minimum interval time is the time required for the controller to send a token to the I / O module to reply to the data; In the downlink direction, the optical module adopts the continuous working mode. After the optical module completes sending a data packet, it continues to send the scrambled signal.

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