OPC UA-based industrial equipment plug-and-produce method and system

Abstract

The present invention belongs to the field of industrial communications, and relates to an OPC UA-based industrial equipment plug-and-produce method and system. Equipment plug-and-produce at a network level is realized by designing an OPC UA-based automatic discovery mechanism; and equipment parameter configuration and integration standardization are realized by designing OPC UA information modeling for all industrial controllers and field equipment and using an OPC UA as a standard interface for inter-equipment communication. By designing an equipment parameter configuration method and an equipment integration method, parameter configuration of equipment and automatic integration between industrial controllers and field equipment are completed, thereby realizing equipment plug-and-produce at a semantic level; and by designing an equipment replacement method, real-time configuration parameters of old equipment that has failed or needs to be upgraded can be automatically transferred to new equipment, thereby reducing the time required for manual equipment replacement. The present invention reduces the time required for integrating and commissioning large-scale heterogeneous industrial equipment and systems, and eliminates potential human errors.

Description

A plug-and-play method and system for industrial equipment based on OPC UA Technical Field

[0001] This invention belongs to the field of industrial communication and relates to a plug-and-play method and system for industrial equipment based on OPC UA. Background Technology

[0002] Distributed control systems play a crucial role in Industry 4.0, providing manufacturing enterprises with in-depth insights through real-time data acquisition and analysis. This enables enterprises to make smarter decisions, optimize production processes, and achieve higher levels of automation. This real-time decision-making and responsiveness allows manufacturing enterprises to adjust production plans more flexibly to meet rapidly changing market demands. However, with rapidly changing production needs, when industrial control systems adjust to new requirements, they often involve equipment and systems from different manufacturers. These devices and systems may use different data models and communication protocol standards, leading to difficulties in data exchange. Simultaneously, during the integration and commissioning of large-scale equipment and systems, engineers require significant manual work for installation, configuration, and integration to ensure all devices are connected and work collaboratively. Manual integration and commissioning not only requires substantial manpower and time costs but is also susceptible to human error. Therefore, there is an urgent need for a hardware-independent "plug-and-play" (PnP) solution for industrial equipment that automates and optimizes equipment configuration and integration, making the process more efficient. Summary of the Invention

[0003] In view of this, the present invention provides a plug-and-play method and system for industrial equipment based on OPC UA. By constructing an OPC UA information model for industrial controllers and field devices and using OPC UA as a unified and reliable data exchange and communication interface, the system can automatically discover devices, configure parameters, integrate them, and replace old devices.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] In a first aspect, the present invention provides a plug-and-play method for industrial equipment based on OPC UA, the method comprising the following steps:

[0006] S1: Embed function blocks in the OPC UA information model of all industrial controllers and field devices, and embed parameter blocks in the OPC UA information model of all field devices;

[0007] S2: All industrial controllers and field devices register with the OPC UA local discovery server through their embedded OPC UA server;

[0008] S3: The PNP service middleware configures the dynamic parameters of field devices based on the device parameter configuration method and by utilizing the parameter blocks in the OPC UA information model of the field devices; it also automatically integrates industrial controllers and field devices based on the device integration method and by utilizing the function blocks in the OPC UA information model of the industrial controllers and field devices.

[0009] S4: The PNP service middleware, based on the device replacement method, uses parameter blocks in the OPC UA information model of the field device to transfer the real-time configuration parameters of the old field device that needs to be replaced to the new field device.

[0010] In a second aspect, the present invention provides a plug-and-play industrial equipment system based on OPC UA, the system comprising a PNP service middleware, an OPC UA local discovery server, an industrial controller embedded with an OPC UA server, and field devices; the PNP service middleware is used to aggregate and store the OPC UA information model of the industrial controller and field devices, and to realize automatic configuration, automatic integration, and parameter transfer when replacing old equipment; the OPC UA local discovery server is used to register the URL information of registered OPC UA servers; the industrial controller and field devices embedded with OPC UA servers are used for real-time monitoring, command execution, and data exchange in the industrial environment.

[0011] Furthermore, the system also includes an upper-layer monitoring application, which serves as a human-machine interface for implementing human-machine control.

[0012] The beneficial effects of this invention are:

[0013] This invention addresses the significant labor and time costs associated with integrating and debugging large-scale field devices in distributed control systems. It provides an automated, efficient, and hardware-independent plug-and-play solution for industrial devices based on OPC UA. By designing an OPC UA-based automatic discovery mechanism, it achieves plug-and-play functionality at the network layer. Furthermore, by designing OPC UA information modeling for all industrial controllers and field devices and using OPC UA as the standard interface for inter-device communication, and by designing device parameter configuration and integration methods, it completes the parameter configuration of devices and the automatic integration between industrial controllers and field devices, thereby achieving plug-and-play functionality at the semantic level. Finally, by designing a device replacement method, it enables the automatic transfer of real-time configuration parameters from faulty or upgradeable older devices to new devices, reducing the time required for manual device replacement. This invention significantly reduces the time required for engineers to integrate and debug large-scale heterogeneous industrial devices and systems, while eliminating human error that may be introduced by manual operation.

[0014] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0015] Figure 1 is a structural diagram of an industrial equipment plug-and-play system based on OPC UA in an embodiment of the present invention;

[0016] Figure 2 is a flowchart of a plug-and-play method for industrial equipment based on OPC UA in an embodiment of the present invention;

[0017] Figure 3 shows the registration architecture diagram of the industrial controller and field device OPC UA server in the embodiment of the invention;

[0018] Figure 4 is a schematic diagram of the dynamic parameter configuration method for industrial equipment in a preferred embodiment of the present invention;

[0019] Figure 5 is a flowchart of the automatic integration method of industrial controller and field device in a preferred embodiment of the present invention;

[0020] Figure 6 is a schematic diagram of an industrial equipment replacement method in a preferred embodiment of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] Plug-and-play solutions for industrial control systems aim to improve system flexibility, reduce deployment and maintenance costs, and accelerate system integration. As an open, standard, and cross-platform communication protocol, the Open Platform Communications Unified Architecture (OPC UA) features a unified information model and standardized communication interfaces, enabling seamless data exchange and communication between industrial devices. Furthermore, its object-oriented architecture allows for interoperability of vendor-independent industrial equipment, providing a viable solution for the installation, configuration, and integration of industrial control systems.

[0023] Figure 1 is a structural diagram of a plug-and-play industrial equipment system based on OPC UA in an embodiment of the invention. As shown in Figure 1, the system includes a PNP service middleware, an OPC UA local discovery server, an industrial controller embedded with an OPC UA server, and field devices. The PNP service middleware is used to aggregate and store the OPC UA information model of the industrial controller and field devices, and to realize automatic configuration, automatic integration, and parameter transfer when replacing old equipment. The OPC UA local discovery server is used to register the URL information of registered OPC UA servers. The industrial controller and field devices embedded with an OPC UA server are used for real-time monitoring, command execution, and data exchange in the industrial environment.

[0024] In some embodiments, the OPC UA local discovery server is responsible for registering the URL information of registered OPC UA servers. Specifically, it can be divided into two types of local discovery servers: Device LDS-ME and Controller LDS-ME. The main difference between the two lies in the different registration objects they record. The former primarily handles network registration requests from field device OPC UA servers, while the latter handles network registration requests from industrial controller OPC UA servers.

[0025] In some embodiments, the industrial controller is responsible for executing a pre-set control algorithm, monitoring and controlling various parameters and variables in the industrial process, while the field device is a sensor responsible for data acquisition or an actuator that executes control commands.

[0026] In a preferred embodiment of the present invention, the system further includes an upper-level monitoring application, which serves as a human-machine interface for implementing human-machine control. The operator, as an OPC UA client, operates the corresponding upper-level monitoring application to perform human-machine operations on the industrial automation system, such as entering configuration parameter information of field devices and updating information of field devices.

[0027] In some embodiments, in the overall architecture of the present invention, industrial controllers #1 to #n integrate the OPC UA server program and the industrial controller control program, and field devices #1 to #m integrate the OPC UA server program and the field device program; here, n and m are just general terms, and the specific number of industrial controllers and industrial devices is determined by those skilled in the art based on the actual situation.

[0028] In the overall architecture of this invention, all components use OPC UA as the unified communication protocol. For resource-constrained field devices or those with fieldbus and analog connections, this invention employs a resource-rich border gateway to act as an agent for running the OPC UA server for these devices, thereby enabling them to become intelligent IoT devices with IP connectivity and capable of data communication via OPC UA.

[0029] Figure 2 is a flowchart of a plug-and-play method for industrial equipment based on OPC UA. As shown in Figure 2, the method includes:

[0030] S1: Embed function blocks in the OPC UA information model of all industrial controllers and field devices, and embed parameter blocks in the OPC UA information model of all field devices;

[0031] In this embodiment of the invention, during the construction of the OPC UA information model for the industrial controller and field devices, due to the different functions and requirements of different devices, the parameter blocks and function blocks in the constructed OPC UA information model will have certain differences. Therefore, the parameter blocks and function blocks must be defined and classified in detail. The parameter blocks include essential parameters for the field devices (parameters crucial to the normal operation of the devices) and optional parameters (parameters configured according to the actual needs of the user). The function blocks include the input variables, output variables, and communication cycles of the industrial controller and field devices. Those skilled in the art may decide to add other information models to the industrial controller and field devices based on the actual situation.

[0032] S2: All industrial controllers and field devices register with the OPC UA local discovery server through their embedded OPC UA server;

[0033] In this embodiment of the invention, the OPC UA local discovery server is used to register the URL information of registered OPC UA servers. Specifically, it can be divided into two types of local discovery servers: Device LDS-ME and Controller LDS-ME. The main difference between the two lies in the different registration objects they record. The former mainly handles network registration requests from field device OPC UA servers, while the latter handles network registration requests from industrial controller OPC UA servers. Having two types of local discovery servers facilitates the automatic integration of industrial controllers and field devices by the PNP service middleware, effectively distinguishing between them.

[0034] S3: The PNP service middleware configures the dynamic parameters of field devices based on the device parameter configuration method and by utilizing the parameter blocks in the OPC UA information model of the field devices; it also automatically integrates industrial controllers and field devices based on the device integration method and by utilizing the function blocks in the OPC UA information model of the industrial controllers and field devices.

[0035] In this embodiment of the invention, the PNP service middleware establishes communication connections with the registered industrial controllers and field device OPC UA servers, respectively, and browses the information models in the OPC UA server address space. It then aggregates and saves the function block information models in the industrial controller OPC UA servers and the function block and parameter block information models in the field device OPC UA servers. The PNP service middleware ensures, through callback functions, that the node data in the aggregated and saved parameter block information models of all devices remains consistent with the node data in the parameter block information models of each device's own OPC UA server. The PNP service middleware provides operators with a unified OPC... The UA interface enables dynamic parameter configuration for all field devices. This configuration method shields the differences in underlying network structure and devices, providing a unified device control and management interface for the upper-level network management system, thus solving the problem of unified configuration for heterogeneous network devices in industrial fields. The PNP service middleware matches the aggregated and stored input / output variable sets of industrial controller function blocks with the input / output variable sets of field device function blocks based on matching rules such as identical input / output signal names or node IDs. Based on the matching results, it enables subscription of industrial controller input signals to field device output signals and vice versa. This subscription can be achieved using OPC UA client / server connections or OPC UA publish / subscribe connections with or without agents. This automatic integration method for industrial controllers and field devices automatically establishes communication between their input / output signals based on the device's information model, significantly reducing integration and debugging time in the factory and eliminating human error from manual operation.

[0036] S4: The PNP service middleware, based on the device replacement method, uses parameter blocks in the OPC UA information model of the field device to transfer the real-time configuration parameters of the old field device that needs to be replaced to the new field device.

[0037] In this embodiment of the invention, the operator specifies the identification information of the old device to be replaced to the PNP service middleware, and then broadcasts a pause command to all devices, causing the OPC UA servers of all devices to enter a hold-up state. Simultaneously, the operator sends a command to the old device to close its communication connections with other devices and its own server. The operator manually disconnects the physical connection of the old device, connects to and starts the new device. After the new device starts running, it registers with the OPC UA local discovery server. The PNP service middleware connects to the new device through the registration information and updates the configuration parameters of the old device to the new device's server. The PNP service middleware re-matches the inputs and outputs of all devices and controllers according to rules, and re-establishes communication connections between the devices and controllers based on the matching results. Then, it broadcasts a normal operation command to all devices. This device replacement method can automatically transfer the real-time configuration parameters of the old device to the new device and automatically reintegrate the new device with other devices, enabling the new device to quickly establish normal data communication with other devices, thereby reducing the time required for manual device replacement.

[0038] Figure 3 is a registration architecture diagram of the industrial controller and field device OPC UA server in a preferred embodiment of the present invention. As shown in Figure 3, it includes:

[0039] 101. The OPC UA server of the industrial controller or field device creates a corresponding OPC UA client and establishes a communication connection with the local discovery server. If the local discovery server is offline or unavailable, the OPC UA client of the industrial controller or field device will periodically attempt to connect to the local discovery server until a communication connection is successfully established; wherein, the periodic connection attempt time is determined by those skilled in the art based on the actual situation, for example, 10 minutes may be used.

[0040] 102. The OPC UA client created by the OPC UA server of the industrial controller or field device sends a registration request message with its own URL and other information to the local discovery server.

[0041] The registration request message includes a general request header, the OPC UA server hostname, the OPC UA server IP address, and the port number.

[0042] 103. After receiving the registration request, the local discovery server saves the URL and other information of the OPC UA server in the registration request message in its internal list of registered OPC UA servers.

[0043] 104. All field device-related OPC UA local discovery servers (Device LDS-ME) share their internally stored lists of registered field device OPC UA servers via the mDNS service. All industrial controller-related OPC UA local discovery servers (Controller LDS-ME) share their internally stored lists of registered controller OPC UA servers via the mDNS service. Registered OPC UA servers periodically register with the local discovery server. If the local discovery server does not receive a re-registration request from a registered OPC UA server within a certain period, it will remove the server's information from the list of registered OPC UA servers. When an OPC UA server stops operating normally, it will send a deregistration request to the local discovery server, which will respond to the request and remove the server's information from the list of registered OPC UA servers.

[0044] As shown in Figure 3, Device LDS-ME is responsible for handling the registration of field devices and forming a list of registered field device OPC UA servers in the PNP service middleware; Controller LDS-ME is responsible for handling the registration of industrial controllers and forming a list of registered controller OPC UA servers in the PNP service middleware. These server lists include the device name and corresponding address information of the registered devices.

[0045] Figure 4 is a schematic diagram of the dynamic parameter configuration method for industrial equipment in a preferred embodiment of the present invention. As shown in Figure 4, the specific interactive process of dynamic parameter configuration for industrial equipment according to the present invention is described. The operator, the upper-layer monitoring application that can act as an OPC UA client, the PNP service middleware, the OPC UA local discovery server, and the industrial field device OPC UA server are the main participants in the dynamic parameter configuration of the equipment. The OPC UA local discovery server is actually Device LDS-ME, which is mainly responsible for handling the registration request of the field device OPC UA server. After registration is completed, the corresponding dynamic parameter configuration can be performed. The dynamic parameter configuration method for industrial equipment includes:

[0046] 201. The PNP service middleware creates the corresponding OPC UA client and connects to the OPC UA local discovery server. It obtains the URL information of the registered field device OPC UA server from the OPC UA local discovery server, and then creates multiple OPC UA clients to connect to the registered field device OPC UA server in sequence.

[0047] 202. The PNP service middleware obtains the parameter block information model from the registered field device OPC UA server; aggregates and saves the parameter block information model of all registered field device OPC UA servers, and aggregates and saves the configuration parameter nodes to their server address space.

[0048] When the PNP service middleware aggregates information model nodes in each OPC UA server, it uses the source server IP address and source server port number to form a string as the namespace for storing the NodeId of the aggregated node. The NodeId of each aggregated node is consistent with the identifier of the node in the source server, thereby ensuring the uniqueness of the NodeId.

[0049] 203. When the PNP service middleware saves the parameter block information model node in each OPC UA server, it binds a callback function to it to monitor the changes in the attribute values ​​of the parameter block information model node.

[0050] If the attribute value of any node in the aggregated storage changes, the callback function will synchronize the updated attribute value of the node to the attribute value of the corresponding node in the address space of the OPC UA server of the field device where the node was originally located through the write function, thereby enabling dynamic parameter configuration of the field device.

[0051] In a preferred embodiment of the present invention, as shown in FIG4, it may further include:

[0052] 204. The operator connects to the PNP service middleware through the OPC UA client of the upper-layer monitoring application. First, the operator modifies the configuration parameters in the upper-layer monitoring application, and then modifies the attribute values ​​of the nodes in the parameter block information model of the specified field device stored in its address space through the PNP server middleware. After the node attribute values ​​are modified, the PNP service middleware automatically calls and executes the callback function bound to the node when it was saved, thereby completing the parameter configuration of the field device.

[0053] Figure 5 is a flowchart of the automatic integration method of industrial controller and field device in a preferred embodiment of the present invention. As shown in Figure 5, after the industrial controller and field device start up and complete configuration, the automatic integration of industrial controller and field device includes:

[0054] 301. The PNP service middleware creates an OPC UA server and completes the parameter configuration for its own server;

[0055] 302. The PNP service middleware creates an OPC UA client and connects to the Device LDS-ME and Controller LDS-ME respectively;

[0056] 303. Periodically query Device LDS-ME and Controller LDS-ME respectively to see if any new field device OPC UA servers or industrial controller OPC UA servers are joining the network;

[0057] The periodic connection attempt time is determined by those skilled in the art based on the actual situation, and is generally 1 second. It is recommended to keep it as short as possible, but the hardware device situation needs to be considered.

[0058] 304. If a new field device OPC UA server joins the network, the PNP service middleware connects to the newly joined field device's OPC UA server and aggregates and saves its function block information model. If a new industrial controller OPC UA server joins the network, the PNP service middleware connects to the newly joined industrial controller's OPC UA server and aggregates and saves its function block information model.

[0059] When the PNP service middleware aggregates information model nodes in each OPC UA server, it uses a string formed by the source server IP address and the source server port number as the namespace for storing the NodeId of the aggregated node. The NodeId of each aggregated node is consistent with the node's identifier in the source server, thus ensuring the uniqueness of the NodeId.

[0060] 305. If it is a newly registered field device OPC UA server, the PNP service middleware will match the input and output signals of the newly registered field device with the input and output signals of all industrial controllers that have been aggregated and stored in the address space of the PNP service middleware in the order of registration of the newly registered field device OPC UA server.

[0061] If the PNP service middleware fails to match a suitable industrial controller for a newly added field device, it indicates that the required industrial controller for the field device is not yet online. Therefore, when the OPC UA server for a newly added industrial controller comes online, the PNP service middleware will attempt to match the input and output signals for that field device again. If the matching still fails, it will need to wait for the next time a new industrial controller comes online on the OPC UA server before attempting to match again, until the correct industrial controller is successfully matched for the field device.

[0062] 306. If it is a newly registered industrial controller OPC UA server, the PNP service middleware will match the input and output signals of the newly registered industrial controller with the input and output signals of all field devices that have been aggregated and stored in the address space of the PNP service middleware in the order of registration of the newly registered industrial controller OPC UA server.

[0063] If the PNP service middleware fails to match a suitable field device for a newly added industrial controller, it indicates that the required industrial controller is not yet online. Therefore, when the OPC UA server for a newly added field device comes online, the PNP service middleware attempts to match the input / output signals for that industrial controller again. If matching still fails, it needs to wait for the next time the OPC UA server for a newly added field device comes online and try matching again until the correct field device is successfully matched for the industrial controller.

[0064] 307. When the input / output signals of the field device are successfully matched with the input / output signals of the industrial controller, the PNP service middleware enables subscription to the industrial controller's input signals and the field device's output signals, as well as subscription to the field device's input signals and the industrial controller's output signals. This subscription can be achieved using an OPC UA client / server connection, or using an OPC UA publish / subscribe connection with or without a proxy. After the subscription is complete, the industrial controller and the field device can communicate normally.

[0065] Figure 6 is a schematic diagram of the industrial equipment replacement method in a preferred embodiment of the present invention. As shown in Figure 6, the process mainly includes the operator specifying the old equipment to be replaced and changing the status of all equipment, transferring the configuration parameters of the old equipment to the new equipment, and the new equipment automatically integrating and restoring the operation of all equipment. Here, the operator also refers to the upper-layer monitoring application that can be used as an OPC UA client. For the sake of brevity, the upper-layer monitoring application is omitted.

[0066] The process involves the operator specifying the old device to be replaced and changing the status of all devices. First, the operator inputs the IP address and port number of the device to be replaced through the method function interface provided by the PNP service middleware, thus specifying the old device to be replaced to the PNP service middleware. Upon receiving this instruction, the PNP service middleware broadcasts a UDP-based hold command message across the network, notifying all devices to enter hold operation mode, meaning all devices cease data exchange. Then, the PNP service middleware causes the old device to close its established data communication channels with other devices.

[0067] The PNP service middleware transfers the configuration parameters of the old device stored in its address space to the OPC UA server of the new device. The operator manually disconnects the physical connection of the old device and connects and starts the new device. Once the new device powers on and starts its OPC UA server, it automatically registers with the Device LDS-ME. The PNP service middleware then retrieves the URL information of the new device from the Device LDS-ME. Based on this URL information, the PNP service middleware connects to the OPC UA server of the new device and synchronously updates the parameter values ​​in the old device configuration parameter information model stored in the PNP service middleware to the OPC UA server of the new device.

[0068] The new device automatically integrates and restores the operation of all devices. First, the PNP service middleware re-matches the input / output signals of the new device with the input / output signals of all industrial controllers according to matching rules. Upon successful matching, a data communication channel is established between the new device and these industrial controllers. Subsequently, the PNP service middleware broadcasts commands via UDP to restore all devices to normal operation.

[0069] The matching rule is that if the node names are the same, the match is successful. If the industrial controller and the equipment use different input and output signal names, the matching may also depend on other information, such as the NodeId of the OPC UA node.

[0070] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An OPC UA-based plug and play system for industrial devices, characterized in that, The system comprises a PNP service middleware, an OPC UA local discovery server, an industrial controller embedded with an OPC UA server and a field device; the PNP service middleware is used to aggregate and save the OPC UA information model of the industrial controller and the field device, and to realize automatic configuration, automatic integration and parameter transfer when replacing the old device; the OPC UA local discovery server is used to register the URL information of the registered OPC UA server; the industrial controller embedded with the OPC UA server and the field device are used for real-time monitoring, instruction execution and data exchange in the industrial environment.

2. The OPC UA-based industrial device plug and play system according to claim 1, wherein, The system further comprises an upper monitoring application program; the upper monitoring application program is used as a man-machine interface to realize man-machine control.

3. An OPC UA-based method for plug and play of industrial devices, characterized in that, The method comprises the following steps: S1: embedding a function block in the OPC UA information model of all industrial controllers and field devices, and embedding a parameter block in the OPC UA information model of all field devices; S2: registering and registering all industrial controllers and field devices through the embedded OPC UA server to the OPC UA local discovery server; S3: the PNP service middleware realizes dynamic parameter configuration of the field device according to the device parameter configuration method and by using the parameter block in the OPC UA information model of the field device; and realizes automatic integration of the industrial controller and the field device according to the device integration method and by using the function block in the OPC UA information model of the industrial controller and the field device; S4: the PNP service middleware realizes real-time configuration parameter transfer from the old field device to be replaced to the new field device according to the device replacement method and by using the parameter block in the OPC UA information model of the field device.

4. The OPC UA-based industrial device plug and play method of claim 3, wherein, The parameter block comprises necessary parameters and optional parameters of the field device, and the function block comprises input variables, output variables and communication cycles of the industrial controller and the field device.

5. The OPC UA based industrial device plug and play method of claim 3, wherein, The step S2 specifically comprises: The OPC UA server of the industrial controller or the field device creates a corresponding OPC UA client and establishes a communication connection with the OPC UA local discovery server; if the OPC UA local discovery server is not online, the OPC UA client will periodically attempt to connect the OPC UA local discovery server until the communication connection is successfully established; The OPC UA client created by the OPC UA server of the industrial controller or the field device sends a registration request message with the URL information of the OPC UA server to the OPC UA local discovery server; after receiving the registration request, the OPC UA local discovery server saves the URL information in the registered OPC UA server list in the OPC UA local discovery server; All field device related OPC UA local discovery servers share the registered field device OPC UA server list saved in them through the mDNS service; all industrial controller related OPC UA local discovery servers share the registered controller OPC UA server list saved in them through the mDNS service; The OPC UA server registered successfully registers with the OPC UA local discovery server periodically; if no re-registration request from the registered OPC UA server is received for a period of time, the OPC UA local discovery server deletes the information of the OPC UA server; when the OPC UA server stops running normally, a deregistration request is sent to the OPC UA local discovery server.

6. The OPC UA based industrial device plug and play method of claim 3, wherein, The device parameter configuration method comprises: The PNP service middleware creates corresponding OPC UA clients, connects with the OPC UA local discovery server, obtains the URL information of the registered field device OPC UA server, and then creates multiple OPC UA clients to connect with the registered field device OPC UA server in sequence; the PNP service middleware aggregates and saves the parameter block information model of all registered field device OPC UA servers; When the PNP service middleware aggregates the parameter block information model nodes in each OPC UA server, a string formed by the IP address of the source server and the Port number of the source server is used as the namespace of the NodeId of the aggregated and saved nodes, and the NodeId of each aggregated node is consistent with the identification of the node in the source server; When the PNP service middleware saves the parameter block information model nodes in each OPC UA server, a callback function is bound to the parameter block information model nodes, which is used to monitor the changes of the attribute values of the parameter block information model nodes; once the attribute values of the parameter block information model nodes change, the callback function synchronizes the updated attribute values to the attribute values of the corresponding nodes in the address space of the field device OPC UA server where the parameter block information model nodes are originally located, thereby realizing the dynamic parameter configuration of the field device.

7. The OPC UA based industrial device plug and play method of claim 6, wherein, The device parameter configuration method further comprises: The operator connects to the PNP service middleware through the OPC UA client of the upper monitoring application program, modifies the attribute values of the nodes in the parameter block information model of the specified field device saved in the address space, and once the modification is completed, the PNP service middleware automatically calls the callback function bound to the node during saving, thereby completing the parameter configuration of the field device.

8. The OPC UA based industrial device plug and play method of claim 3, wherein, The device integration method comprises: The PNP service middleware respectively requests the OPC UA local discovery server for the OPC UA server list information of the registered industrial controller and field device through the OPC UA client; The PNP service middleware establishes a communication connection with each registered OPC UA server by using the OPC UA server list information of the registered industrial controller and field device; The PNP service middleware aggregates and saves the function block information model nodes in all registered industrial controller OPC UA servers, including the input and output signals of the control logic program of the industrial controller and the input and output signals of the field device; The PNP service middleware matches the corresponding industrial controller for each field device in the order of registration of all registered field device OPC UA servers; when the PNP service middleware finds the same input and output signal name in the input and output variable set of the function block information module of the field device from the input and output variable set of all function block information modules of the industrial controller saved by the aggregation, it is considered that the matching is successful; or the PNP service middleware matches the appropriate field device for all registered industrial controllers in the order of registration of all registered industrial controllers; when the PNP service middleware finds the same input and output signal name in the function block information module of the industrial controller from the input and output variable set of all function block information modules of the field device saved by the aggregation, it is considered that the matching is successful; if the industrial controller and the field device use different input and output signal names, the matching is performed according to the NodeId; After the matching is successful, the PNP service middleware enables the subscription of the industrial controller input signal and the field device output signal, and the subscription of the field device input signal and the industrial controller output signal, thereby realizing automatic integration.

9. The OPC UA based industrial device plug and play method of claim 7, wherein, The subscription adopts an OPC UA client / server connection or an OPC UA publish / subscribe connection with or without an agent.

10. The OPC UA based industrial device plug and play method of claim 3, wherein, The device replacement method comprises: The PNP service middleware receives instruction information from an operator, and the instruction information specifies device identification information to be replaced; The PNP service middleware broadcasts a keep command to all field devices in the network, so that the OPC UA servers of all field devices enter a keep state, i.e., do not perform data interaction, and sends a command to the old field device to close the communication connection with other field devices and close the OPC UA server of the old field device; The physical connection of the old field device is disconnected, and the physical connection of the new field device is connected and started; The OPC UA server of the new field device is started and registered with the OPC UA local discovery server; The PNP service middleware requests the OPC UA local discovery server to obtain the OPC UA server list information of the new field device; connects to the new field device, and updates the parameter values in the parameter block information model of the old field device saved in the OPC UA server address space of the PNP service middleware to the OPC UA server of the new field device; The PNP service middleware re-executes step S3 for all field devices and industrial controllers, and broadcasts a normal operation command to all field devices, so that they resume normal operation and continue production.

Images