Servo driver management method based on DB data mapping and authority management
By adopting DB data mapping and permission management methods in servo drive management, the problems of complex user-defined parameter management and lack of unified specifications in the prior art are solved, and efficient and safe parameter management and equipment operation are achieved.
Patent Information
- Application Number
- CN202411966171.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-04-25
AI Technical Summary
The existing servo drive management technology is difficult to effectively manage user-defined parameters under PROFINET communication, resulting in complex parameter identification and configuration, and lack of unified specifications for user permission management, which affects the safety of equipment operation.
The servo drive management method based on DB data mapping and permission management is adopted. By initializing the mapping of the DB database and standard PROFINET parameters, the parameters are automated management and integration are realized, and the DB data display interface is loaded according to user permissions to ensure that only authorized users can access and modify key parameters.
Improve the efficiency and security of parameter management, reduce the need for manual configuration and management, ensure data accuracy and consistency, enhance device compatibility and user-friendliness, and reduce the complexity of memory management and the security risks of device operation.
Smart Images
Figure CN119883338A_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the technical field of servo drives, and in particular, relates to a servo drive management method based on DB data mapping and authority management. Background Art
[0002] In the context of the rapid development of industrial automation technology, servo drives, as the core components of precision motion control, have a direct impact on the operating efficiency and accuracy of automation equipment. Servo drives ensure the efficiency and stability of production lines by precisely controlling motor movement. With the development of industrial Ethernet technology, PROFINET has become one of the mainstream protocols for servo drive communication, which provides reliable guarantee for real-time data exchange between the drive and the host computer.
[0003] In the specific application scenarios of the PROFINET communication protocol, the parameters of the servo drive are like the "instruction set" for its operation. Accurate parameter configuration and efficient management are the core elements to ensure its high-performance operation. These parameters include not only the speed, position and torque settings of the motor, but also the fault diagnosis, safety functions and user-defined parameters of the drive. In the current technology, the parameter access of the servo drive can use non-periodic data read and write operations under PROFINET communication, but this method will cause certain errors when facing user-defined parameters and unclear read and write permissions.
[0004] If PROFINET communication is not used, the customized parameter numbers of various equipment manufacturers lack unified standards and often conflict with PROFINET standard parameter numbers, increasing the difficulty of parameter identification and device configuration, and affecting device compatibility. Parameter data is stored in multiple memory areas in a scattered manner. Although there is a certain degree of flexibility, memory management is complicated. Engineers need to be familiar with the characteristics of each area, which is prone to errors and wastes resources, and also reduces the response speed of the drive. At the same time, there is a lack of unified standards for user authority management, and sensitive parameters are easily modified at will, threatening the safety of equipment operation.
[0005] From the perspective of equipment manufacturers, in addition to following a series of standard parameters created by the PROFINET standard, the parameter settings of servo drives often require manufacturers to add a large number of custom parameters based on specific application scenarios or user needs. When these custom parameters are numbered, they are likely to overlap or conflict with existing standard PROFINET parameter numbers. This conflict not only makes parameter identification difficult, but may also lead to problems such as parameter setting errors and system configuration confusion. In actual operation, engineers may need to spend a lot of time checking and adjusting parameter numbers to avoid conflicts, which undoubtedly increases the complexity of equipment configuration and the probability of errors. In addition, parameter number conflicts may also affect the compatibility and interchangeability of equipment, causing inconvenience to equipment maintenance and upgrades.
[0006] In existing servo drive designs, parameter data is often stored in multiple memory areas of the device, such as EEPROM, FLASH, etc. Distributed storage makes the memory structure complex and increases the difficulty of memory management. When engineers perform parameter configuration or system maintenance, they need to be familiar with the specific conditions of each memory area, which undoubtedly increases the workload and error probability. Distributed storage is not conducive to the optimal use of memory and may lead to a waste of memory resources.
[0007] In the prior art, there is no unified standard for the management of user operation permissions. Some manufacturers do not manage and restrict user permissions, which makes it possible for sensitive parameters to be easily modified by unauthorized users. Such improper modifications will not only affect the normal operation of the device, causing device performance degradation or malfunction, but may also cause serious data security incidents. For example, malicious users may steal device data, destroy device functions or even the entire control system by modifying sensitive parameters, which brings huge security risks and losses to device users. Summary of the invention
[0008] The purpose of this application is to provide a servo drive management method based on DB data mapping and permission management. By combining the design of user debugging software and servo drive program, it realizes the mapping of standard PROFINET parameters, access permission management, data upload / download and non-volatile processing functions.
[0009] In order to achieve the above-mentioned purpose, the embodiment of the present application provides a servo drive management method based on DB data mapping and authority management, including: Initialize DB database and standard PROFINET parameter mapping; Load the DB data display interface according to user permissions; When the user triggers an upload / download request, the servo drive processes the upload / download request accordingly, wherein the upload includes reading the parameter data in the servo drive EEPROM to the debugging software, and the download includes writing the parameter data in the debugging software into the servo drive EEPROM; Verify the status of the servo drive. If the status supports it, execute the upload / download request, update the parameter data on the DB data display interface, and write it to the EEPROM to complete non-volatile storage.
[0010] According to the above method of the embodiment of the present application, the following additional technical features may also be provided: Furthermore, the DB database and standard PROFINET parameter mapping are initialized, including: In the DB database, index area division is performed for the standard PROFINET parameters, and based on the index area division, a mapping relationship between the standard PROFINET parameters and the DB database is established.
[0011] Furthermore, in the DB database, index area division is performed for the standard PROFINET parameters, and based on the index area division, a mapping relationship between the standard PROFINET parameters and the DB database is established, including: Set user access levels and parameter attributes for each standard PROFINET parameter, and fill the standard PROFINET parameters and their parameter attributes into the DB database.
[0012] Furthermore, the user access levels include primary user, secondary user, and tertiary user; the parameter attributes include DB_ID, description, and user authority; Among them, user permissions correspond to user access levels. The user permissions corresponding to level three users are read-only access, the user permissions corresponding to level two users are read-write access, and the user permissions corresponding to level one users are read-write access and management operations.
[0013] Furthermore, the DB data display interface is loaded according to the user's authority, including: Read the data from the DB database through the debugging software and save the data in advance to the cache of the debugging software; When the user logs in to the debugging software, the user's permissions are verified, and according to the user's permissions, the DB data corresponding to the user's permissions are filtered out in the debugging software's cache; The DB data corresponding to the user authority is loaded and filtered out in the cache of the debugging software to the DB data display interface of the debugging software.
[0014] Further, when the user triggers an upload / download request, the servo drive processes the upload / download request accordingly, wherein the upload includes reading the parameter data in the servo drive EEPROM to the debugging software, and the download includes writing the parameter data in the debugging software into the servo drive EEPROM, verifying the status of the servo drive, and executing the upload / download request if the status supports it, updating the parameter data in the DB data display interface, and writing it into the EEPROM to complete non-volatile storage, including: When the user triggers an upload request, the servo driver receives the upload request command from the debugging software, and determines whether the parameter data upload is supported according to the data status and operation status of the servo driver; if the status supports upload, the servo driver packages the parameter data and sends it to the debugging software; after receiving the packaged parameter data through the debugging software, the parameter data on the DB data display interface is parsed and updated; When the user triggers a download request, the servo driver receives the download request command from the debugging software, and determines whether the parameter data download is supported according to the data status and operation status of the servo driver; if the status supports downloading, the servo driver receives the parameter data sent from the debugging software; the servo driver parses and updates the received parameter data; After the update is completed, all updated parameter data will be written into the servo drive EEPROM to complete non-volatile data storage.
[0015] Furthermore, communication is performed between the servo drive and the debugging software via a specific communication protocol.
[0016] Compared with the prior art, the servo drive management method based on DB data mapping and authority management provided by the embodiment of the present application has the following beneficial technical effects: The embodiment of the present application realizes automatic management and integration of parameters by initializing the mapping between the DB database and the standard PROFINET parameters, reduces the need for manual configuration and management, and improves work efficiency. By setting the user access level and parameter attributes for each standard PROFINET parameter and filling them into the DB database, the accuracy and consistency of the data are ensured, the failure and downtime caused by data errors or inconsistencies are reduced, the communication errors caused by unclear read and write permissions are effectively avoided, and the problem of parameter number conflicts is solved.
[0017] The embodiment of the present application ensures that only authorized users can access and modify key parameters by loading the DB data display interface according to user permissions, thereby enhancing security and preventing unauthorized access and potential security risks.
[0018] The embodiment of the present application displays the DB data interface loaded according to the user's authority, so that the user can only see the parameters and data related to his authority, thereby improving the usability and user-friendliness of the interface and reducing the user's learning cost.
[0019] The embodiment of the present application supports users to easily upload and download parameter data of the servo drive through debugging software, simplifies the parameter configuration process, improves the convenience of maintenance, and the updated parameter data is written to the EEPROM of the servo drive, realizing non-volatile storage, ensuring that the parameter data remains unchanged even after power failure or restart, thereby improving the stability and reliability of the system, reducing the memory area switching overhead, simplifying the complexity of memory management, and improving system efficiency.
[0020] The embodiment of the present application ensures the compatibility and interoperability between the servo drive and the debugging software by adopting a specific communication protocol. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 A flow chart of a servo drive management method based on DB data mapping and authority management according to an embodiment of the present application is shown. DETAILED DESCRIPTION
[0022] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. It is to be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some structures related to the present application are shown in the accompanying drawings, rather than all structures. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.
[0023] The terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.
[0024] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.
[0025] DB database usually refers to a database, which is a warehouse that organizes, stores and manages data according to data structures.
[0026] PROFINET was launched by PROFIBUS International (PI) and is a new generation of automation bus standard based on industrial Ethernet technology. As a real-time industrial communication standard, it aims to achieve data transmission and efficient communication between devices, and the number of nodes installed worldwide has exceeded 40 million.
[0027] like Figure 1 As shown, the embodiment of the present application provides a servo drive management method based on DB data mapping and authority management, comprising the following steps: Step 101, initializing the DB database and standard PROFINET parameter mapping.
[0028] Step 101 involves the initialization of the DB database and the mapping to standard PROFINET parameters. The purpose of this step is to provide basic data support for subsequent user permission management, upload / download of parameter data, and status verification of servo drives, etc.
[0029] Specifically, in the DB database, the index area is divided for standard PROFINET parameters as shown in the following table: Table 1 Parameter Group Index range in DB database PROFINET parameter group 1 11520<DB_ID<11776 PROFINET parameter group 2 (reserved) 11776<DB_ID<12032 It is set that the index range for the mapping division of standard PROFINET parameters in the DB database is 11520 < DB_ID < 11776, corresponding to PROFINET parameter group 1, with a total of 256 pieces of data.
[0030] This application embodiment also reserves a group of index ranges of 11776 < DB_ID < 12032 as PROFINET parameter group 2. This reserved area is mainly to cope with future product updates and function expansion requirements. During subsequent product upgrades, newly added or adjusted PROFINET parameters can be reasonably allocated to the index range of this parameter group 2, ensuring that the entire DB database architecture has good scalability and compatibility and can adapt to changing technologies and application scenarios.
[0031] To ensure that in the subsequent parameter management and data interaction processes, each parameter can be specified to correspond to a specific DB data location and avoid index conflicts and chaos. It is necessary to fill in the corresponding parameter attributes for each piece of data, including DB_ID, description, user permission, length, type, read / write support, maximum value, minimum value, default value, etc.
[0032] This step is to effectively organize and manage the data in the DB database. By allocating a specific index area for each standard PROFINET parameter, it is convenient to quickly search for and locate these parameters.
[0033] After completing the index area division, it is necessary to establish a mapping relationship between the standard PROFINET parameters and the DB database. This mapping relationship ensures that each standard PROFINET parameter can be associated with the corresponding data in the DB database, thus realizing the unified management and access of data.
[0034] In order to ensure data security and controllability, it is necessary to set user access levels and parameter attributes for each standard PROFINET parameter. User access levels can be divided according to different user permissions, such as primary users, secondary users, and tertiary users. Parameter attributes include DB_ID (database identifier), description, and user permissions.
[0035] At the same time, in order to meet the PROFINET standard communication requirements and to increase the modularity and readability of the code, the embodiment of the present application also establishes a data table for describing standard PROFINET parameters and creates a structure named PDRIVE_PAR_OBJ, which includes elements such as "Pnu", "Identifier", "Number Of Elements", "Read Function", "WriteFunction", and "DBIndex".
[0036] The "Pnu" element is used to store the specific number of the PROFINET parameter, which is set according to the PROFINET standard specification so that the parameters can be uniformly identified within the PROFINET system; the "Identifier" element provides the type of parameter data, including descriptions such as data grouping, data type, and data read and write permissions; the "Number Of Elements" element specifies the number of data elements associated with the parameter to ensure the integrity and accuracy of data reading and writing; the "ReadFunction" and "WriteFunction" elements point to the read and write functions for the parameter, respectively, encapsulating the specific read and write operation logic.
[0037] The "DBIndex" element plays a key mapping and connection role, corresponding to the "DB_ID" in the DB database, thereby successfully building a mapping relationship between the standard PROFINET parameter data table and the DB database.
[0038] When the "DB_ID" in the read / write request sent by the servo drive debugging software corresponds to the specified standard PROFINET parameter, the "Read / Write function" function pointer in the PDRIVE_PAR_OBJ structure will be automatically called to perform the read / write operation of the PROFINET parameter, and the "NumberOf Elements" will be used to ensure that the data volume of the read / write operation is accurate.
[0039] After completing the above steps, the standard PROFINET parameters and their parameter attributes need to be filled into the DB database. In this way, when users need to access these parameters, they can quickly search and obtain them through the DB database.
[0040] User access level and permissions description: Level 3 users have read-only access rights, that is, they can only view parameter data but cannot modify or delete it; Level 2 users have read-write access rights, that is, they can view and modify parameter data but cannot perform management operations (such as adding new users, modifying user permissions, etc.); Level 1 users have read-write access and management operation rights, that is, they can view, modify parameter data, and perform management operations.
[0041] In addition, the embodiments of the present application may also adopt a dynamic permission allocation strategy to dynamically adjust user permissions based on factors such as user operation behavior, device operation status, etc. For example, during normal operation of the device, a level 3 user may only have read-only permissions, but when the device fails, according to preset rules, permissions are automatically temporarily elevated for specific level 3 users, allowing them to view some key diagnostic parameters or perform some repair operations.
[0042] Detailed description of parameter attributes: DB_ID is used to uniquely identify a parameter or data item in a database; description is used to briefly explain the parameter or data item to help users understand its meaning and purpose; user rights correspond to user access levels and determine the user's access and operation rights to the parameter or data item.
[0043] In summary, step 101 involves the initialization of the DB database and the mapping with the standard PROFINET parameters. By setting the user access level and parameter attributes for each standard PROFINET parameter and filling these parameters and their attributes into the DB database, basic data support is provided for subsequent user authority management, parameter data upload / download, and servo drive status verification.
[0044] Step 102, loading the DB data display interface according to the user authority.
[0045] Step 102 ensures that only users with corresponding permissions can access and view specific DB (database) information. The implementation process of this step can be divided into the following sub-steps: Sub-step 1: Read the data from the DB database through the debugging software.
[0046] First, you need to use the debugging software to read the data in the DB database. The debugging software serves as a bridge between the user and the servo drive and is responsible for extracting this data from the DB database.
[0047] Sub-step 2: Pre-save the data into the cache of the debugging software.
[0048] In order to improve the efficiency and speed of data access, the data read from the DB database is saved in advance in the cache of the debugging software. In this way, when the user needs to access this data, it can be read directly from the cache without accessing the DB database again, thereby reducing the delay of data access.
[0049] Sub-step three: When the user logs in to debug the software, the user's permissions are verified.
[0050] When a user logs in to the debugging software, the user's permissions will be verified. This step is key to ensuring data security. Based on the user's login information (such as user name and password), it is checked whether the user has the permission to access the debugging software and what specific permission level they have.
[0051] Sub-step 4: Based on the user permissions, filter out the DB data corresponding to the user permissions in the cache of the debugging software.
[0052] Once the user's permissions are verified, the corresponding DB information will be filtered according to the user's permission level. This means that users with different permission levels will only see the data and information related to their permissions. This step helps to protect the confidentiality and integrity of the data and prevent unauthorized users from accessing sensitive information.
[0053] Sub-step 5: Load the DB data corresponding to the user authority selected from the cache of the debugging software to the DB data display interface of the debugging software.
[0054] Finally, the filtered DB data will be loaded into the DB data display interface of the debugging software. In this way, users can see the data and information related to their permissions. The implementation of this step involves multiple aspects such as data formatting, rendering and display to ensure that users can clearly see the required information.
[0055] In summary, step 102 ensures that only users with corresponding permissions can access and view specific DB data through multiple sub-steps. The implementation of this step not only improves the efficiency and speed of data access, but also enhances the security and confidentiality of data.
[0056] Step 103, when the user triggers an upload / download request, the servo drive processes the upload / download request accordingly, wherein uploading includes reading the parameter data in the servo drive EEPROM to the debugging software, and downloading includes writing the parameter data in the debugging software into the servo drive EEPROM; verifying the status of the servo drive, and executing the upload / download request if the status supports it, updating the parameter data in the DB data display interface, and writing it into the EEPROM to complete non-volatile storage.
[0057] When the user needs to upload or download the parameter data of the servo drive, the corresponding request will be triggered through the debugging software. After receiving these requests, the servo drive will perform a series of processing.
[0058] During the upload process, the servo drive first receives the upload request command from the debugging software, and then it determines whether it supports the upload of parameter data based on its own data status and operating status. This usually involves checking whether the drive is in an idle state and whether there are enough resources to process the upload request.
[0059] If the status supports uploading, the servo drive will package the parameter data to be uploaded and send it to the debugging software through a specific communication protocol. After receiving the packaged parameter data, the debugging software will parse it and update the parsed data to the DB data display interface for users to view.
[0060] The download process is similar to the upload process. The servo drive first receives the download request command from the debugging software. Similarly, it will determine whether it supports the download of parameter data based on its own data status and operating status. If the status supports downloading, the servo drive will receive the parameter data sent from the debugging software and parse it. The parsed data will be used to update the parameter settings inside the servo drive.
[0061] After the update is completed, the servo drive will write all the updated parameter data to its EEPROM to ensure non-volatile data storage. This means that even if the drive is powered off or restarted, these parameter data will not be lost.
[0062] In the above process, the communication between the servo drive and the debugging software is achieved through a specific communication protocol. Specific communication protocols are more suitable for certain brands or models of servo drives and debugging software, thereby ensuring the best compatibility and performance, and using specific communication protocols is more cost-effective than using standard protocols (such as PROFINET), especially in applications that require a large number of device connections or large amounts of data transmission. In addition, specific communication protocols can be customized according to specific application requirements to meet specific communication requirements, such as data transmission rate, data format, etc.
[0063] It should be noted that the embodiment of the present application can also use FLASH storage instead of EEPROM to store DB information parameter data.
[0064] In summary, step 103 describes a complete servo drive parameter data upload / download process. This process involves multiple links such as user request processing, status verification, data encapsulation and sending / receiving and parsing, data updating, and non-volatile storage. With the support of a specific communication protocol, these links can be completed efficiently and reliably.
[0065] It should be noted that, in the present application, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises one..." does not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be noted that the scope of the method and device in the embodiment of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.
[0066] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.
Claims
1. A servo drive management method based on DB data mapping and authority management, characterized in that: The method comprises: Initialize DB database and standard PROFINET parameter mapping; Load the DB data display interface according to user permissions; When the user triggers an upload / download request, the servo drive processes the upload / download request accordingly, wherein the upload includes reading parameter data in the servo drive EEPROM to the debugging software, and the download includes writing parameter data in the debugging software into the servo drive EEPROM; Verify the status of the servo drive, and if the status supports it, execute the upload / download request, update the parameter data of the DB data display interface, and write it into the EEPROM to complete non-volatile storage.
2. The servo drive management method according to claim 1, characterized in that: The initialization DB database and standard PROFINET parameter mapping include: In the DB database, index area division is performed for the standard PROFINET parameters, and based on the index area division, a mapping relationship between the standard PROFINET parameters and the DB database is established.
3. The servo drive management method according to claim 2, characterized in that: In the DB database, index area division is performed for the standard PROFINET parameters, and based on the index area division, a mapping relationship between the standard PROFINET parameters and the DB database is established, including: A user access level and parameter attributes are set for each standard PROFINET parameter, and the standard PROFINET parameter and its parameter attributes are filled into the DB database.
4. The servo drive management method according to claim 3, characterized in that: The user access levels include level one user, level two user and level three user; the parameter attributes include DB_ID, description and user authority; Among them, the user rights correspond to the user access levels, the user rights corresponding to the third-level users are read-only access, the user rights corresponding to the second-level users are read-write access, and the user rights corresponding to the first-level users are read-write access and management operations.
5. The servo drive management method according to claim 1, characterized in that: The loading of the DB data display interface according to user authority includes: Reading the data from the DB database through the debugging software and pre-saving the data into the cache of the debugging software; When a user logs into the debugging software, the user authority is verified, and according to the user authority, DB data corresponding to the user authority is screened out in the cache of the debugging software; The DB data corresponding to the user authority is selected and loaded into the DB data display interface of the debugging software in the cache of the debugging software.
6. The servo drive management method according to claim 1, characterized in that: When the user triggers an upload / download request, the servo drive processes the upload / download request accordingly, wherein the upload includes reading the parameter data in the servo drive EEPROM to the debugging software, and the download includes writing the parameter data in the debugging software into the servo drive EEPROM, verifying the status of the servo drive, and executing the upload / download request if the status supports it, updating the parameter data in the DB data display interface, and writing it into the EEPROM to complete non-volatile storage, including: When the user triggers an upload request, the servo driver receives the upload request command from the debugging software, and determines whether the parameter data upload is supported according to the data status and operation status of the servo driver; if the status supports the upload, the servo driver encapsulates and packages the parameter data and sends it to the debugging software; after receiving the encapsulated parameter data through the debugging software, the parameter data of the DB data display interface is parsed and updated; When the user triggers a download request, the servo driver receives the download request command from the debugging software, and determines whether the parameter data download is supported according to the data state and the operation state of the servo driver; if the state supports the download, the servo driver receives the parameter data sent from the debugging software; and the servo driver parses and updates the received parameter data; After the update is completed, all updated parameter data are written into the servo drive EEPROM to complete the non-volatile data storage.
7. The servo drive management method according to any one of claims 1 to 6, characterized in that: The communication between the servo drive and the debugging software is performed through a specific communication protocol.