CN119420790A

CN119420790A - Industrial control system and communication method thereof

Info

Publication number: CN119420790A
Application number: CN202411542116.8A
Authority: CN
Inventors: 陈银桃; 王雅莉; 谢燕鹏; 周位强; 王坤皇
Original assignee: Zhongkong Technology Co ltd
Current assignee: Zhongkong Technology Co ltd
Priority date: 2024-10-31
Filing date: 2024-10-31
Publication date: 2025-02-11

Abstract

The invention provides an industrial control system and a communication method thereof, wherein the communication system comprising a passive optical network and a bus expansion module is adopted, so that transmission links from a main frame to a plurality of slave frames can be realized, a plurality of communication modules are not required, the cost of the industrial control system is reduced, meanwhile, the passive optical network forwards signals, the transmission efficiency is high, the problem of large delay of forwarding by adopting the communication modules one by one is avoided, the communication efficiency is improved, the cost is reduced, the system stability is improved, and the more efficient, reliable and economical industrial control system is realized.

Description

Industrial control system and communication method thereof

Technical Field

The invention belongs to the technical field of communication, and particularly relates to an industrial control system and a communication method thereof.

Background

In an industrial control system, a controller module plays a core role, periodically collects real-time data of an I/O module, performs necessary operation processing on the data, and periodically outputs a processing result back to the I/O module so as to realize real-time control and monitoring of the system. With the development of industrial automation, the application scenes of remote IO are increased, which puts higher demands on the communication efficiency and reliability of a control system. Currently, a communication network is built in an industrial control station mainly through a local IO bus and an extended IO bus so as to support complex IO device connection and data transmission.

At present, a framework that a main frame is connected to a remote frame through a communication module is adopted, and the communication module on any frame is not only connected with an I/O module of the same frame through a local IO bus, but also communicated with the remote frame through an efficient data transmission protocol, so that a more flexible and efficient bus type connection network is formed.

However, more communication modules need to be configured, which results in higher cost of the industrial control system and greater delay in forwarding data by the communication modules.

Disclosure of Invention

In view of the above, an object of the present invention is to provide an industrial control system and a communication method thereof for improving communication efficiency, reducing cost and improving system stability, so as to realize a more efficient, reliable and economical industrial control system.

The application discloses an industrial control system, which comprises a main frame, a communication system and a remote frame, wherein the communication system comprises a passive optical network and a bus expansion module;

the main frame is connected with a first end of the passive optical network through a first bus expansion module;

n second ends of the passive optical network are in one-to-one correspondence with N second bus expansion modules, and each second end in the passive optical network is connected with the first end of the corresponding second bus expansion module;

the second end of the second bus expansion module is connected with different remote racks;

the main frame is connected with the first bus expansion module by a BLVDS base plate;

the remote rack is connected with the second bus expansion module by a BLVDS base plate;

The main frame, the passive optical network, the first bus expansion module, the second bus expansion module and the remote frame form a star network structure.

Optionally, 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 is used as the core of the IO bus communication network of the industrial control system, and each bus expansion module is used as the communication unit of the IO bus communication network of the industrial control system.

Optionally, the passive optical network comprises an optical fiber and an optical splitter;

one end of the optical fiber is connected with the first bus expansion module;

the other end of the optical fiber is connected with one end of the optical splitter;

The N second ends of the optical splitter are used as N second ends of the passive optical network.

Optionally, the number of the remote racks is 15.

Or the number of the communication systems is 2 or 1.

Alternatively, the IO bus signal is encoded using 8B/10B balanced encoding.

Optionally, the bus expansion module comprises a BLVDS interface, an FPGA and an optical interface module supporting EPON/GPON;

The BLVDS interface is connected with a BLVDS base plate corresponding to the BLVDS interface;

the optical interface module is connected with the passive optical network;

the FPGA is used for realizing signal forwarding and controlling the optical interface module.

The second aspect of the application discloses a communication method of an industrial control system, comprising the following steps:

And controlling the flow scheduling of the uplink data of the passive optical network by adopting a token scheduling mode in the industrial control system.

Optionally, the industrial control system adopts a token scheduling mode to control the flow scheduling of the uplink data of the passive optical network, and the method comprises the following steps:

Transmitting target data of the main frame to each remote frame through a transmission link by adopting a broadcasting technology, wherein the target data comprises an address of the target remote frame;

each remote rack judges whether the address of the remote rack is consistent with the address of the target remote rack in the received target data;

if yes, the target remote rack sends response data to the main rack through a transmission link.

Optionally, the method further comprises:

A link scheduler in the bus extension module monitors the link state in real time, and when the link state is abnormal, the link scheduler retrieves target data.

Optionally, 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 finishes receiving a data packet, waiting for the minimum interval time, wherein the minimum interval time is the time required by a controller to issue a token to an I/O module for replying data;

In the downlink direction, the optical module adopts a continuous working mode, and continuously transmits a scrambling signal after the optical module finishes transmitting one data packet.

According to the technical scheme, the industrial control system provided by the invention adopts the communication system comprising the passive optical network and the bus expansion module, so that the transmission link from the main frame to a plurality of remote frames can be realized, a plurality of communication modules are not needed, the cost of the industrial control system is reduced, meanwhile, the passive optical network forwards signals, the transmission efficiency is high, the problem of large delay caused by the fact that the communication modules are adopted for forwarding one by one is avoided, the communication efficiency is improved, the cost is reduced, the system stability is improved, and the industrial control system which is more efficient, reliable and economical is realized.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of an industrial control system provided by an embodiment of the present invention;

FIG. 2 is a schematic diagram of another industrial control system provided by an embodiment of the present invention;

FIG. 3 is a flow chart of token scheduling involved in another industrial control system provided by an embodiment of the present invention;

Fig. 4 is a timing diagram of operation of an optical module related to another industrial control system according to an embodiment of the present invention.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In the present disclosure, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises an element. Furthermore, the terms first, second, third, fourth and the like in the description and in the claims and in the above drawings, if any, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the application described herein may be implemented, for example, in sequences other than those illustrated or otherwise described herein.

The embodiment of the application provides an industrial control system, which is used for solving the problems that in the prior art, more communication modules are required to be configured, so that the cost of the industrial control system is higher, and the communication modules have larger delay in forwarding data.

Referring to fig. 1, the industrial control system comprises a main frame, a communication system and a remote frame, wherein the communication system comprises a passive optical network and a bus expansion module.

The main chassis is connected to a first end of a passive optical network (including optical fibers and optical splitters as shown in fig. 1) through a first bus extension module (bus extension module a as shown in fig. 1).

Specifically, the main frame is connected with a BLVDS interface of the first bus expansion module, and an optical port of the first bus expansion module is connected with a first end of the passive optical network.

The main frame is connected with the first bus expansion module by a BLVDS base plate.

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

It should be noted that, the low voltage differential signal is transmitted between the main frame and the first bus expansion module, and the low voltage differential signal is a signal with the same amplitude and opposite phase transmitted on two signal lines simultaneously by adopting a differential transmission technology. The receiving end judges the logic state sent by the sending end by comparing the difference value of the two signals.

The low voltage differential signal has strong anti-interference capability. Because the interference noise is generally equivalent and is simultaneously loaded on the two signal lines, and the receiving end only concerns about the difference value of the two signals, the external common mode noise can be completely counteracted.

The low voltage differential signal is effective in suppressing electromagnetic interference (EMI). Because the two wires are close together and the signal amplitude is equal, the amplitude of the coupling electromagnetic field between the two wires and the ground wire is also equal, and the signal polarities of the two wires are opposite, the magnetic force lines can cancel each other, and the electromagnetic radiation is reduced.

The low voltage differential signal has the advantage of accurate time sequence positioning. The receiving end of the low-voltage differential signal is the point of positive and negative jump of the signal amplitude difference between the two wires, and is used as the point for judging the logic 0/1 jump. The transmission mode is more suitable for low-amplitude signals and is less influenced by the ratio of threshold voltage to signal amplitude voltage.

Low voltage differential signals are commonly used for high speed data transmission interfaces. The interfaces have the advantages of low power consumption, low noise, high anti-interference capability, high speed and the like, and are suitable for point-to-point or multipoint communication.

N second ends of the passive optical network are in one-to-one correspondence with N second bus expansion modules (such as the limit bus expansion modules B\C\D shown in fig. 1), and each second end of the passive optical network is connected with the first end of the corresponding second bus expansion module.

Specifically, the 1 st second end of the passive optical network is connected with the first end of the 1 st second bus expansion module, the 2 nd second end of the passive optical network is connected with the first end of the 2 nd second bus expansion module, and the N second end of the passive optical network is connected with the first end of the N second bus expansion module.

The second end of the second bus extension module is connected with a different remote rack.

Specifically, the N second bus extension modules are in one-to-one correspondence with the N remote racks, and the second ends of the second bus extension modules are connected with the corresponding remote racks.

More specifically, the second end of the 1 st second bus expansion module is connected with the 1 st remote rack, the second end of the 2 nd second bus expansion module is connected with the 2 nd remote rack, and so on, the second end of the N th second bus expansion module is connected with the N th remote rack. Of course, it is not excluded that the second ends of the 1 second bus extension modules are connected to at least 2 remote racks, which are not described in detail herein, and they are all within the protection scope of the present application according to the actual situation.

Each remote rack is a slave rack.

The remote rack is connected with the second bus expansion module by a BLVDS base plate.

Specifically, the remote rack is connected to one end of the BLVDS chassis, and the BLVDS interface (second end) of the second bus extension module is connected to the other end of the BLVDS chassis. Transmitted between the remote chassis and the second bus extension module is a low voltage differential signal.

That is, a point-to-multipoint communication network is implemented.

Each node (e.g., remote chassis) in the star network architecture is connected to a central node (e.g., mainframe) by an independent link (e.g., optical fiber). The structure ensures that the faults of single nodes can not influence the operation of the whole network, thereby improving the reliability of the network. The passive optical network is used as an important component part, adopts all-fiber transmission, has the characteristics of high bandwidth, long transmission distance and strong anti-interference capability, and further enhances the reliability of the network.

The star network structure is easy to expand and maintain. When new nodes need to be added, the new nodes only need to be connected to the main frame through the bus expansion module. Passive optical network technology also supports flexible bandwidth allocation and dynamic network access, and can provide customized services according to the needs of different users.

Compared with a bus type structure, the star network structure has a shorter data transmission path, and reduces delay and loss of data transmission.

The passive optical network technology adopts a broadcast mode downlink and a time division multiple access mode uplink, so that network resources can be efficiently utilized, and the throughput of the network is improved.

In this embodiment, a communication system including a passive optical network and a bus extension module is adopted, so that a transmission link from a main frame to a plurality of remote frames can be realized, a plurality of communication modules are not required, and the cost of an industrial control system is reduced.

Optionally, the mainframe 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 the local IO bus.

The mainframe is a highly integrated collection of components that encompasses the communication module, controller, and I/O modules. These modules are all connected to the local IO bus, forming an efficient, interoperable system.

The controller clearly plays a vital role. The system is not only a central brain of an IO bus communication network of an industrial control system, is responsible for dispatching and management of the whole network, but also is a key place for ensuring stable operation and high-efficiency data processing of the system.

At the same time, the individual bus expansion modules also play an indispensable role. The method is similar to bridges and ties in a communication network, and each node is closely connected, so that accurate and rapid information transmission is ensured. As a communication unit of an IO bus communication network of the industrial control system, the bus expansion module provides a solid foundation for expansion and upgrading of the system.

That is, the mainframe constructs an industrial control system IO bus communication network with powerful and flexible and expandable functions through integrating the communication module, the controller, the I/O module and the bus expansion module.

In this embodiment, the controller of the mainframe is used as the core of the IO bus communication network, and the bus extension module is used as the communication unit to forward the IO bus. The network communication based on the protocol, namely the broadcast mode downlink and the time division multiple access mode uplink, has the characteristics of low cost, low time delay and high reliability.

Optionally, the passive optical network comprises an optical fiber and an optical splitter.

One end of the optical fiber is connected with the first bus extension module, and the other end of the optical fiber is connected with one end of the optical splitter.

Specifically, one end of the optical fiber is tightly connected with the first bus expansion module, so that efficient transmission of signals is ensured, and the other end of the optical fiber is in seamless connection with one end of the optical splitter, so that the coverage range of a network is further expanded.

The optical splitter is used as a key node in the network and is provided with N second ends, and the ports are used as N output ports of the passive optical network to provide access services for a plurality of terminal devices.

It is worth noting that the connection medium between the optical splitter and the first bus extension module is an optical fiber, and the connection mode not only ensures the high-speed performance and stability of data transmission, but also greatly improves the reliability and flexibility of the whole passive optical network.

Optionally, the number of remote racks is 15.

That is, a total of 16 remote racks and mainframe may enable 16 racks to communicate.

Alternatively, the IO bus signal is encoded using 8B/10B balanced encoding.

The 8B/10B balance coding is adopted to code the IO bus signals, so that the effects of direct current balance, signal quality, clock recovery, data synchronization, error detection, data verification, coding efficiency, compatibility and the like can be realized. The method comprises the following steps:

dc balance and signal quality. The direct current balance is ensured, that is, the 8B/10B coding ensures that the quantity of 0 and 1 in the coded data is approximately equal through the carefully designed mapping rule, and the continuous occurrence of 0 or 1 of long strings is avoided. The DC balance characteristic is helpful to reduce DC offset of the signal in the transmission process, reduce signal distortion, and improve signal quality. Optimizing the signal spectrum 8B/10B coding can shift the energy of the low band to the high band, similar to the effect of a high pass filter. This helps to keep the frequency domain curve flat after the transmission channel, effectively alleviates intersymbol interference (ISI), and improves the reliability of data transmission.

Clock recovery is synchronized with the data. The 8B/10B coding ensures that there are enough edge transitions in the data stream that provide a basis for clock recovery at the receiving end. The receiving end can recover the clock signal by detecting the edge transitions, thereby realizing the synchronization of data transmission. No external clock is needed, and because the 8B/10B code can embed clock information, no extra distributed clock is needed in the transmission process. The problems of clock deflection, flight time and the like in parallel transmission are avoided, the system design is simplified, and the speed and stability of data transmission are improved.

Error detection and data verification. There are 1024 possible patterns for the 8B/10B encoded 10 bit data with error detection capability, but only 536 of them are valid codewords. The receiving end can determine whether the transmission is erroneous by checking whether the received codeword is in the valid codeword list. Such error detection capability helps to discover and correct errors in the transmission in a timely manner. The addition of signal check 8B/10B encoding also provides additional check bits that can be used for data alignment and transmission of control commands. By setting and checking the check bit, the accuracy and reliability of data transmission can be further improved.

Coding efficiency and compatibility. Coding efficiency although 8B/10B coding introduces 20% of the overhead (coding 8 bits of data into 10 bits of data), its advantages in terms of ensuring dc balance, clock recovery and error detection make this overhead worthwhile. In addition, through ingenious coding design, 8B/10B coding can also improve the transmission efficiency of data to a certain extent. The 8B/10B code has wide application in the fields of Ethernet, optical fiber communication, PCIe, SATA, USB 3.0.0 and other high-speed serial interfaces. The wide compatibility enables 8B/10B coding to be a standard coding mode, and facilitates data transmission between different devices and systems.

In summary, the use of 8B/10B balanced encoding to encode the IO bus signal has many advantages, including ensuring dc balance and signal quality, facilitating clock recovery and data synchronization, having error detection and data verification capabilities, and broad compatibility and certain encoding efficiency. These advantages have led to the widespread use and acceptance of 8B/10B codes in high-speed serial communications.

The photoelectric receiving and transmitting system comprises a main device, a main optical module connected with the main device through a cable, an optical splitter connected with the main optical module, N slave optical modules connected with the optical splitter through optical fibers, N slave devices connected with the N slave optical modules through cables respectively, wherein N is a positive integer not smaller than 2, and the slave devices are in communication connection with the main device based on the slave optical modules, the optical splitter and the main optical module.

Compared with the application, the photoelectric receiving and transmitting system only has the connection mode of the optical network and the control of the optical transceiver, and has no scheduling mechanism of data flow in the point-to-multipoint network. And when electric signal transmission is carried out in the cable, bus protocols such as Profibus-DP, modbus, CAN are adopted, the transmission rates of the protocols are low, the control mode of the optical transceiver is complex and difficult to control through a preset coding mode in the scheme, low-speed data transmission can be met, and the method is not suitable for high-speed data transmission application.

The application adopts a token scheduling mode of a broadcast mode downlink and a time division multiple access mode uplink, performs scheduling on data streams in a point-to-multipoint network, transmits by using low-voltage differential signals, improves transmission efficiency, adopts an 8B/10B balance coding mode, has simple control and meets the requirement of high-rate data transmission.

Alternatively, the number of communication systems is 2 (as shown in fig. 2) or 1 (as shown in fig. 1).

That is, two sets of communication systems are arranged between the main frame and each remote frame, so that communication redundancy is realized.

In order to further improve the reliability of IO bus data communication, the communication system adopts a redundancy configuration strategy, and the redundancy design of the data A/B network is specifically realized. This design means that the system has two independent data communication paths, namely a-net and B-net. Under normal conditions, the two network paths can simultaneously or respectively bear the data transmission tasks, so that the efficiency and fault tolerance of data transmission are improved.

It is particularly important that the redundant configuration ensures that data communication between the controller and the remote I/O module is not interrupted when critical components such as the optical module or the optical splitter fail. The system can automatically switch to a standby network path to continuously complete a data transmission task, so that the risk of paralysis of the whole communication system caused by single-point faults is effectively avoided.

In summary, by adopting the redundancy configuration strategy, the communication system not only improves the reliability of data communication, but also enhances the fault tolerance and stability of the system, and provides a solid technical guarantee for various application scenes.

Optionally, the bus extension module comprises a BLVDS interface, an FPGA and an optical interface module supporting EPON/GPON.

The BLVDS interface connects its own corresponding BLVDS backplane.

The optical interface module is connected with the passive optical network.

The IO bus network (comprising a bus expansion module, an optical splitter and an optical fiber) is of a star network structure. One side of the bus expansion module is connected with the frame through a cable, the other side of the bus expansion module is connected with the passive optical network through the self optical interface module, and the bus expansion module is connected with a plurality of bus expansion modules to form a star-shaped structure. In the rack, the controllers are interconnected with the IO and the IO are interconnected with the IO through a BLVDS backplane bus. The first bus expansion modules are root nodes of the passive optical network, and the second bus expansion modules are terminal nodes of the passive optical network.

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

In this network, the first bus expansion module plays a key role of the root node of the passive optical network, and each second bus expansion module serves as a terminal node of the passive optical network, so as to jointly maintain the stable operation of the network. The bus expansion module not only has the capability of converting the BLVDS bus signal into the passive optical network signal, but also supports reverse conversion, thereby realizing perfect fusion of the two networks. Each bus expansion module is at least provided with an optical port (namely an optical interface module) and a BLVDS interface, and the optical port can flexibly select an EPON/GPON optical transceiver so as to meet the requirements under different scenes.

The core of the network is a bus expansion module, which utilizes a programmable logic chip FPGA to realize the forwarding of signals and the accurate control of an optical transceiver. The design not only improves the transmission efficiency of the network, but also ensures the stability and reliability of signals.

In addition, the signal transmission of the industrial control system is simultaneously carried out in the full-duplex BLVDS backplane bus and the passive optical network, and the transmission distance of the optical fiber reaching 20Km is supported, so that the coverage range of the network is greatly expanded. Meanwhile, the system can also support IO bus connection of at most 16 racks, and provides powerful support for signal transmission of an industrial control system.

In order to enhance the compatibility of the bus extension modules, the scheme is designed that the first bus extension module is matched with the GPON/EPON OLT optical transceiver to serve as a root node of a network, and the second bus extension module is matched with the GPON/EPON ONU optical transceiver to serve as a terminal node of the network. To achieve this objective, I2C bus technology is integrated into the bus expansion module for obtaining class information of the optical transceiver. By identifying the specific type of optical transceiver, a precise control strategy can be implemented for different types of optical transceivers. This design not only promotes system flexibility, but also ensures perfect compatibility of the bus expansion module with various optical transceivers.

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

The communication method of the industrial control system comprises the following steps:

and the industrial control system adopts a token scheduling mode to control the flow scheduling of the uplink data of the passive optical network.

It should be noted that, the Token scheduling model is shown in fig. 3, wherein MASTERLAS is a controller of the main frame, slave 1/2/3/n is a Slave frame (remote frame), token is target data, and response is response data.

That is, the master chassis issues target data to the slave chassis, which performs data upload in response to the target data. It should be noted that, only one slave rack needs to upload data in each period.

Token scheduling is a token-based access control method that ensures that only one device (the slave chassis) can send data at any time, thereby avoiding data collisions. In a token scheduling system, each device is assigned a unique token that is circulated through the network. Only the device holding the token can transmit data and pass the token to the next device after transmission is completed.

Token assignment in the upstream, each remote chassis or upstream channel is assigned a unique token. The tokens are passed in a predetermined order or rule in the network.

Data transmission, in which only the remote rack holding the token can transmit the upstream data stream. After the transmission is completed, the device passes the token to the next remote rack.

Collision avoidance data collision may be avoided since only one remote rack holds tokens and transmits data at any time. This mechanism ensures the stability and reliability of the upstream.

Token reclamation and reuse-after a token passes through the network one turn, it can return to the starting point for reclamation and reuse. This ensures continuous operation of the token scheduling system.

In the application of time-sharing scheduling of uplink data streams, the token scheduling mode can be realized by the following modes:

The network design is to design a network architecture supporting token scheduling, including a remote rack, an uplink channel, a token passing mechanism and the like.

Token assignment algorithm a token assignment algorithm is developed that ensures that each remote rack is assigned a unique token and passed in a predetermined order or rule.

And the data transmission protocol is established, and the data transmission format, the data transmission speed, the error detection and correction mechanisms and the like are regulated.

Network monitoring and management, namely realizing network monitoring and management functions, including token state monitoring, data transmission state monitoring, fault detection and recovery and the like.

In summary, the token scheduling method can effectively realize time-sharing scheduling of the uplink data stream and avoid uplink data collision. The method has wide application prospect in various fields, such as communication networks, industrial control systems and the like.

In this embodiment, the flow scheduling of the uplink data of the passive optical network is performed by adopting a token scheduling mode, so that only one remote rack can transmit data at any time, and the token scheduling mode can effectively avoid data collision. In addition, as the token is circularly transmitted in the network, each remote rack has the opportunity to send data, thereby improving the utilization rate of the network. Meanwhile, the token scheduling mode simplifies the network management, because the network manager does not need to worry about the problems of data collision, transmission errors and the like.

Optionally, the method for controlling the flow scheduling of the uplink data of the passive optical network by adopting the token scheduling in the industrial control system comprises the following steps:

the method comprises the steps of adopting a broadcasting technology to send target data of a main frame to each remote frame through a transmission link, wherein the target data comprises the address of the target remote frame;

If yes, the target remote rack sends response data to the main rack through the transmission link.

It should be noted that, the controller of the main frame may modify the address in the target data according to a preset sequence or rule, so as to implement effective scheduling of each remote frame. The scheduling can be performed according to a scheduling table, or other scheduling modes are adopted, so that the scheduling is not repeated here, the scheduling is required according to actual conditions, and the scheduling is within the protection scope of the application.

Specifically, when the controller needs to send target data to the I/O module of the remote rack connected with 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 the BLVDS port to the optical port and sends the target data to the passive optical network, the passive optical network sends the target data to all the second bus expansion modules connected with the passive optical network in a broadcasting mode, the optical ports of all the second bus expansion modules are forwarded to the BLVDS interfaces, the BLVDS interfaces of all the second bus expansion modules send the BLVDS interfaces of the corresponding remote rack to the I/O module of the remote rack, the I/O module of the remote rack confirms whether the data is received or not according to the target address in the target data, if the target address is consistent, the target data is received, and if the target address is inconsistent, the target data is not received. If the received data is confirmed, the remote rack prepares the data required by the mainframe and uploads the data to the mainframe.

More specifically, if the controller needs to send data (such as target data) to the remote I/O module connected to the second bus extension module B, the data is sent to the first bus extension module a through the BLVDS bus, the first bus extension module a forwards the signal received by the BLVDS port of the first bus extension module a to the optical port of the first bus extension module a to implement sending to the passive optical network, sends the signal to the second bus extension module B, C, D connected to all the optical splitters in a broadcast manner, and sends the signal to the I/O module on the remote rack after forwarding the signal from the optical port of the second bus extension module to the BLVDS interface, where 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 with the bus expansion module B sends data, the data is sent to the second bus expansion module B through the BLVDS bus, and the second bus expansion module B forwards signals received by the BLVDS port to the passive optical network, sends the signals to the first bus expansion module A through the passive optical network and then sends the signals to the controller of the main frame through the BLVDS.

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 is necessary to ensure that the optical module can perform photoelectric signal conversion normally in the point-to-multipoint communication process. The specific requirement is that the ONU optical module needs to close the transmission enabling in an idle state, and a receiving end of the ONU optical module cannot cause the closing of the optical module or abnormal data receiving due to longer idle time in data communication. Meanwhile, the receiving end of the OLT optical module must be able to quickly recover the optical signals transmitted from the different ONU optical modules, so that the GPON/EPON optical module supporting the burst mode is selected for use. Control of the GPON/EPON OLT and ONU optical modules is therefore required. Among them, GPON/EPON, PON is an optical fiber access technology that uses passive devices to establish network connections. GPON and EPON respectively correspond to different technical standards of the passive optical network. The OLT is an optical line terminal and is equipment of a network provider. ONU, optical network terminal, is the equipment of user end.

The specific control method is as follows:

It should be clear that the communication system network of the present invention adopts a point-to-multipoint star connection. In order to ensure that the bus extension module can smoothly perform data communication, it is necessary to ensure that the optical module can normally perform a task of converting an optical signal in a point-to-multipoint communication process. Specifically, this requires the ONU optical module (optical interface module in the first bus extension module) to turn off its transmission enabling function in an idle state, while not causing the ONU optical module to turn off the reception function or abnormal data reception due to long-time idling in data communication. In addition, the receiving end of the OLT optical module (optical interface module in the second bus extension module) must be able to quickly recover the optical signals from the different ONU optical modules. Thus, a GPON/EPON optical module is selected that supports burst mode.

To achieve this, specific control is required for the GPON/EPON OLT modules and GPON/EPON ONU optical modules. The specific control strategy is as follows:

In the uplink communication direction, the optical module of the transmitting end is a GPON/EPON ONU optical module, and the optical module of the receiving end is a GPON/EPON OLT optical module. Because the system of the invention is not provided with a bandwidth allocation mechanism, the controller of the main frame cannot predict the accurate moment when the I/O module in the remote-mode frame replies the data packet, so that the burst mode control of the optical module is difficult to directly carry out.

Therefore, the invention adopts a control method for burst mode reception of the GPON/EPON optical transceiver, namely, the working process of an optical interface module of a bus expansion module in an industrial control system is as follows:

In the uplink direction, after the optical interface module finishes receiving a data packet, waiting for the minimum interval time, the optical interface module performs reset operation, the detection signal of the optical interface module is pulled down, and when the detection signal of the optical interface module is pulled up, the optical interface module receives a new data packet, wherein the minimum interval time is the time required by the controller to issue a token to the I/O module to reply data.

That is, when the optical module completes receiving a packet of data, it waits for a minimum interval time. Subsequently, the optical module performs a reset operation, and its SD (signal detection) signal is pulled down. The optical module then waits for the SD signal to be pulled high again, indicating that the optical transceiver has successfully received a new signal. Upon detecting that the SD signal goes high, the optical module starts receiving the next packet data. The working time sequence diagram is shown in fig. 4, wherein Optical Input Signal is an optical input signal, and the OLT RX Output is an Output signal of the OLT optical module. RESET is the Output signal of the SD pin, namely the SD (signal detection) signal, and GUARD TIME is the GUARD TIME.

In the downstream direction, the GPON/EPON OLT optical module is used as a transmitting end, and the GPON/EPON ONU optical module is used as a receiving end.

In order to ensure that the receiving-end optical module can continuously and accurately receive data, the transmitting end and the receiving end are set to be in continuous working modes. This means that the transmitting end will not only transmit the optical signal during the transmission of the data packet, but will still continue to transmit the "0101010101" scrambling signal matched to the bit rate of the electrical signal after one data packet is transmitted, so as to maintain the continuity of the optical signal. In addition, the communication protocol of the invention particularly adopts a special code pattern K28.1 as a preamble, and aims to realize accurate alignment of bytes, thereby further improving the accuracy and stability of data transmission.

The data is sent to the main frame by the remote frame in the uplink direction, and the data is sent to the remote frame by the main frame in the downlink direction.

Optionally, the method further comprises:

The link state includes the presence of a loss of target data (token), the initiation of an exception handling scheme when there is at least one of a loss of target data, a failure of the slave chassis to respond within a preset time, and the retraction of target data, i.e., the reclamation of token data, by the link scheduler beyond a maximum bus idle time.

Features described in the embodiments in this specification may be replaced or combined, and identical and similar parts of the embodiments may be referred to each other, where each embodiment focuses on differences from other embodiments. In particular, for a system or system embodiment, since it is substantially similar to a method embodiment, the description is relatively simple, with reference to the description of the method embodiment being made in part. The systems and system embodiments described above are merely illustrative, wherein the elements illustrated as separate elements may or may not be physically separate, and the elements shown as elements may or may not be physical elements, may be located in one place, or may be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art will understand and implement the present invention without undue burden.

Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative elements and steps are described above generally in terms of functionality in order to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

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

Claims

1. An industrial control system, characterized in that it comprises: a main rack, a communication system and a remote rack; the communication system comprises: 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 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 the remote racks is 15;

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

5. The industrial control system according to claim 1 is characterized in that 8B/10B balanced encoding is used to encode the IO bus signal.

6. The industrial control system according to claim 1, characterized in that the bus expansion module comprises: 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, comprising:

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 is 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, further comprising:

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:

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.