Intelligent laboratory management system based on PLC

Abstract

The invention discloses an intelligent laboratory management system based on a PLC, and particularly relates to the technical field of laboratory management, the system takes the PLC as a core, and an RFID personnel management system, an RFID instrument management system, an online examination system, an environment adjusting system, a key system, a human-computer interface, a background recording module and an execution module are integrated; the RFID technology realizes personnel identity verification and intelligent access of instruments, the online examination system prevents cheating through dynamic IP and encryption communication, and the environment adjusting system automatically regulates and controls temperature, humidity and carbon dioxide concentration based on a sensor and a PID algorithm; the key system supports emergency power-off and help seeking functions, the human-computer interface provides a graphical operation interface, and the background recording module adopts a block chain technology to ensure data credibility. The system solves the problems of low efficiency, resource waste, potential safety hazards and the like of traditional laboratory management, remarkably improves the management efficiency, the safety and the energy utilization rate, and is suitable for colleges and scientific research laboratories.

Description

Technical Field

[0001] The present invention relates to the technical field of laboratory management, and more particularly to a PLC-based intelligent laboratory management system. Background Art

[0002] With the development of higher education and scientific research, the traditional laboratory management model has exposed many defects:

[0003] Student sign-in and instrument borrowing and returning rely on manual registration, which is time-consuming, labor-intensive and prone to errors. This is especially true when multiple classes are conducting experiments together. Attendance and equipment inventory are inefficient. Examinations require manual distribution and collection of test papers, making score statistics cumbersome. In addition, traditional written tests are difficult to effectively prevent cheating.

[0004] Experimental instruments lack intelligent tracking methods and are prone to being lost, misplaced, or not returned within a certain time limit. The equipment failure rate is high and the maintenance cost remains high. The power supply and multimedia equipment cannot be controlled in a coordinated manner. Human negligence often causes the equipment to run at no load or waste energy (such as air conditioning and lighting remaining on when no one is around).

[0005] In emergency situations (such as equipment failure and gas leakage), there is a lack of a rapid response mechanism, and delayed manual intervention may cause safety accidents. When the laboratory is crowded with people, the carbon dioxide concentration is likely to exceed the standard (traditional ventilation relies on time switches and cannot be adjusted in real time), and temperature and humidity fluctuations affect experimental accuracy and personnel health.

[0006] Data such as personnel entry and exit, equipment usage, etc. rely on paper records or single-machine storage, lacking traceability and data analysis capabilities, making it difficult to support teaching evaluation and safety audits.

[0007] Therefore, a PLC-based intelligent laboratory management system is proposed. Summary of the Invention

[0008] In order to overcome the above-mentioned defects of the prior art, the present invention provides a PLC-based intelligent laboratory management system to solve the problems raised in the above-mentioned background technology.

[0009] To achieve the above objectives, the present invention provides the following technical solutions: a PLC-based intelligent laboratory management system, comprising:

[0010] PLC controller, as the core control unit;

[0011] RFID personnel management system, one-way connected to the PLC controller, for personnel identification and entry and exit management;

[0012] RFID instrument management system, one-way connected to the PLC controller, for intelligent access management of experimental instruments;

[0013] The online examination system is connected to the PLC controller in a one-way manner, supporting networked examinations and anti-cheating functions;

[0014] Environmental conditioning system, which is unidirectionally connected to the PLC controller and includes temperature, humidity, and carbon dioxide concentration sensors and actuators;

[0015] The key system is one-way connected to the PLC controller and integrates emergency control and help functions;

[0016] Human-machine interface, bidirectionally connected to the PLC controller, serving as an operation and monitoring interface;

[0017] The background recording module and the execution module are connected to the PLC controller in a one-way manner for data storage and equipment control.

[0018] Preferably, the RFID personnel management system includes:

[0019] The campus card reading module, the campus card information verification module and the campus card information matching module are connected in sequence to form a signal link;

[0020] The output end of the PLC controller is connected to the access control system, and personnel authority verification is achieved through RFID wireless radio frequency technology. After successful verification, the PLC controller triggers the access control to open, and the background recording module stores the personnel entry and exit time and experiment duration.

[0021] Preferably, the RFID instrument management system includes:

[0022] The experimental instrument reading module, the experimental instrument verification module and the experimental instrument matching module are connected in sequence to form a signal link;

[0023] The PLC controller controls the solenoid valve of the instrument cabinet through the execution module. When the student selects an instrument through the human-machine interface, the PLC controller triggers the corresponding instrument cabinet to open. If the instrument is not returned correctly after the experiment, the instrument cabinet prompt light will automatically light up and alarm.

[0024] Preferably, the online examination system is built using a D development board of the ESP module, displays examination information through an LCD display, and communicates bidirectionally with an Internet server;

[0025] The system supports dynamic IP address allocation and key encryption. Students can access random IP addresses through their mobile phones or computers to obtain test questions. The background can monitor the test status in real time and automatically generate transcripts.

[0026] Preferably, the environmental conditioning system comprises:

[0027] The temperature and humidity sensor and the carbon dioxide concentration sensor convert analog signals into digital signals through the A / D conversion module and input them into the PLC controller;

[0028] The PLC controller automatically controls the air conditioner, exhaust fan, lights, curtains and other equipment in the execution module according to preset thresholds, realizing intelligent adjustment of laboratory environmental parameters.

[0029] Preferably, the key system includes:

[0030] Help button and emergency stop button, the signal output end is connected to the PLC controller;

[0031] When the help button is pressed, the PLC controller sends a help message to the background and records the number of help requests; when the emergency stop button is pressed, the PLC controller immediately triggers an emergency power off and shuts down the dangerous equipment through the execution module.

[0032] Preferably, the human-machine interface integrates six control modules, including personnel management, instrument management, online examination, environmental adjustment, key system and data monitoring interface;

[0033] Through the graphical interactive interface, managers can view laboratory status in real time, remotely control equipment, and generate equipment usage reports and environmental data reports.

[0034] Preferably, the execution module expansion includes multimedia equipment and a test bench socket control unit;

[0035] The PLC controller can control the multimedia device switch and the power on and off of the laboratory bench in a coordinated manner. Combined with the RFID instrument management system, it can realize the "instrument access-power activation" linkage safety mechanism.

[0036] Preferably, the background recording module is built based on blockchain technology and uses a distributed storage method to record information such as personnel entry and exit, instrument usage, environmental data, and help records;

[0037] The data cannot be tampered with and is traceable, providing a reliable basis for laboratory safety audits, equipment maintenance and teaching evaluation.

[0038] The PLC-based intelligent laboratory management system provided by the present invention has the following beneficial effects:

[0039] The present invention forms a multi-dimensional intelligent management solution by creatively integrating RFID wireless radio frequency technology, ESP8266 Internet of Things module, blockchain distributed storage and PLC linkage control technologies: the RFID personnel / instrument management system realizes contactless access to campus cards and full-process tracking of instrument "retrieval-return", improving the accuracy of personnel entry and exit records and reducing the instrument loss rate; the online examination system uses dynamic IP allocation and AES-256 encryption technology to support multiple people taking concurrent exams and improve the accuracy of cheating detection, completely changing the traditional manual proctoring mode; the environmental adjustment system uses temperature and humidity / PID algorithm to link air conditioners and exhaust fans to improve temperature and humidity control accuracy and reduce energy consumption; the key system and execution module build an "emergency power off-equipment shutdown" millisecond-level response link to reduce safety accidents; the blockchain background recording module based on Hyperledger Fabric improves data audit efficiency and ensures that information such as personnel trajectory and equipment status cannot be tampered with and is traceable in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a block diagram of the laboratory platform principle of the present invention;

[0041] Figure 2 This is the wiring diagram of the RFID read / write controller of the present invention;

[0042] Figure 3 This is a functional block diagram of the RFID personnel management system of the present invention;

[0043] Figure 4 This is a principle block diagram of the RFID instrument management system of the present invention.

[0044] The accompanying drawings are marked as follows: 1. PLC controller; 2. RFID personnel management system; 21. Campus card reading module; 22. Campus card information verification module; 23. Campus card information matching module; 3. RFID instrument management system; 31. Experimental instrument reading module; 32. Experimental instrument verification module; 33. Experimental instrument matching module; 4. Online examination system; 5. Key system; 6. Environmental adjustment system; 7. Background recording module; 8. Execution module; 9. Human-computer interface. DETAILED DESCRIPTION

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0046] As attached Figure 1-4 The PLC-based intelligent laboratory management system shown includes:

[0047] PLC controller 1, serving as the core control unit;

[0048] RFID personnel management system 2, which is unidirectionally connected to the PLC controller 1, is used for personnel identification and entry and exit management;

[0049] RFID instrument management system 3, which is unidirectionally connected to the PLC controller 1 and is used for intelligent access management of experimental instruments;

[0050] The online examination system 4 is unidirectionally connected to the PLC controller 1 and supports networked examinations and anti-cheating functions;

[0051] The environmental conditioning system 6 is unidirectionally connected to the PLC controller 1 and includes temperature, humidity, and carbon dioxide concentration sensors and actuators;

[0052] The key system 5 is unidirectionally connected to the PLC controller 1 and integrates emergency control and help functions;

[0053] Human-machine interface 9, bidirectionally connected to PLC controller 1, serving as an operation and monitoring interface;

[0054] The background recording module 7 and the execution module 8 are respectively connected to the PLC controller 1 in a one-way manner for data storage and device control.

[0055] During implementation, the PLC controller 1 acts as the central processing unit, interacting with various subsystems via I / O interfaces. Subsystems such as the RFID personnel management system 2, the RFID instrument management system 3, and the online examination system 4 transmit collected data to the PLC, which then processes the data according to pre-set logic and sends control instructions to the execution module 8. The human-machine interface 9 communicates bidirectionally with the PLC via the HMI protocol, enabling data visualization and manual intervention.

[0056] Specifically, each subsystem is connected to the PLC's communication port via the RS485 / Modbus protocol. The human-machine interface 9 uses the Kunlun Tongtai TPC1062Hi touch screen, and the background recording module is deployed on the Alibaba Cloud server. A main program is written in the PLC to cyclically scan the status of each subsystem. An interrupt processing mechanism is set up through STEP 7-Micro / WIN SMART to ensure that emergency signals are responded to first, thereby achieving unified management of laboratory equipment and reducing response time. The human-machine interface 9 supports multi-user concurrent operation and extends the system's mean time between failures.

[0057] The RFID personnel management system 2 includes:

[0058] The campus card reading module 21, the campus card information verification module 22 and the campus card information matching module 23 are connected in sequence to form a signal link;

[0059] The output end of the PLC controller 1 is connected to the access control system, and personnel authority verification is achieved through RFID wireless radio frequency technology. After successful verification, the PLC controller 1 triggers the access control to open, and the background recording module 7 stores the personnel entry and exit time and the experiment duration.

[0060] During the specific implementation, an RFID reader (model FM17550) was installed at the entrance of the laboratory. It had a built-in antenna power of 500mW and an effective recognition distance of 8cm. It used the Mifare DESFire EV1 encryption algorithm. The database stored the personnel permission table (students / teachers / administrators). The PLC program set peak hours, such as 8:00-22:00, to automatically open permissions.

[0061] Specifically, the campus card reader module 21 activates the card chip using a 13.56MHz radio frequency signal, reads the unique ID code, and transmits it to the campus card information verification module 22. The verification module compares the ID with a pre-stored database. The campus card information matching module 23 generates an open command or a rejection signal based on the permission level. Upon receiving the result, the PLC controller 1 outputs a 24V signal through the DO module to activate the electromagnetic lock and simultaneously writes a timestamp to the background recording module 7.

[0062] Data flow: campus card → reading module → verification module → matching module → PLC → access control → backend.

[0063] This enables recognition accuracy rates >99.9% and response time <200ms; supports the storage of more than 100,000 permission data items; and increases laboratory utilization by 25% through personnel trajectory analysis.

[0064] The RFID instrument management system 3 includes:

[0065] The experimental instrument reading module 31, the experimental instrument verification module 32 and the experimental instrument matching module 33 are connected in sequence to form a signal link;

[0066] The PLC controller 1 controls the solenoid valve of the instrument cabinet through the execution module 8. When the student selects an instrument through the human-machine interface 9, the PLC controller 1 triggers the corresponding instrument cabinet to open. If the instrument is not returned correctly after the experiment, the instrument cabinet prompt light will automatically light up and alarm.

[0067] During the specific implementation, the UHF reader (model ThingMagic M6e) is installed on the top of the instrument cabinet, with an antenna gain of 6dBi and a coverage range of 1.5m. A state machine program is written in the PLC to set the automatic billing logic for instrument borrowing timeout, such as deducting 10 yuan for every hour exceeding the limit, and notifying the responsible person via text message.

[0068] Specifically, the lab instrument reader module 31 uses ultra-high frequency RFID to scan the electronic tag attached to the instrument, obtaining the instrument ID and status information. The lab instrument verification module 32 checks whether the instrument is available for borrowing, and the lab instrument matching module 33 generates a retrieval and return instruction based on the student's permissions. The PLC controls the instrument cabinet solenoid valve via a relay module and simultaneously updates the instrument status (in use / idle) to the backend. If the instrument is not returned within the preset two-hour time limit, the PLC triggers an audible and visual alarm (85dB buzzer and flashing LED).

[0069] Data flow: instrument tag → reading module → verification module → matching module → PLC → solenoid valve → background.

[0070] This enables multi-tag recognition speeds of >200 tags / second and positioning accuracy of ±5cm; reduces instrument loss rate from 12% to <1%; and increases equipment utilization by 30%.

[0071] The online examination system 4 is built using the D1 development board of the ESP8266 module, displays examination information on an LCD screen, and communicates bidirectionally with an Internet server;

[0072] The system supports dynamic IP address allocation and key encryption. Students can access random IP addresses through their mobile phones or computers to obtain test questions. The background can monitor the test status in real time and automatically generate transcripts.

[0073] In specific implementation, the ESP8266 module is connected to an external 32Mbit Flash memory, which supports the storage of 100 sets of test papers; the LCD screen is connected via an SPI interface, with a display resolution of 128×64 pixels, and uses AES-256 to encrypt data transmission. The OpenCV visual recognition algorithm is deployed on the server side to detect abnormal movements of candidates through the camera.

[0074] Specifically, the D1 development board of the ESP8266 module connects to the lab's WiFi in STA mode and requests a dynamic IP address from the DHCP server. A 12864-dot LCD display shows the exam countdown and test content in real time. Students access a randomly generated URL via their mobile phone. The server, using a PHP+MySQL architecture, polls the test status via AJAX. The system detects cheating by detecting multiple device IP accesses and screenshots.

[0075] Data flow: server → ESP8266 → LCD → student terminal → server → backend.

[0076] It supports concurrent access for ≥50 people, page response time is <1 second, cheating detection accuracy is >95%, and exam organization efficiency is improved by 60%.

[0077] The environmental adjustment system 6 includes:

[0078] The temperature and humidity sensor and the carbon dioxide concentration sensor convert analog signals into digital signals through the A / D conversion module and input them into the PLC controller 1;

[0079] The PLC controller 1 automatically controls the air conditioner, exhaust fan, lights, curtains and other equipment in the execution module 8 according to the preset threshold value, thereby realizing intelligent adjustment of the laboratory environment parameters.

[0080] In the specific implementation, sensors are distributed in the four corners and the center of the laboratory, every 5m 2 One monitoring point was set up; the air conditioner communicated with the PLC via the RS485 interface, supporting the Modbus RTU protocol. The PLC program set an adaptive adjustment strategy. For example, when the number of experimental personnel was ≥20, the ventilation frequency was automatically increased by 20%; when there was no one at night, the temperature threshold was relaxed to 24-26°C.

[0081] Specifically, a DHT22 temperature and humidity sensor collects data with a temperature range of -40-80°C and an accuracy of ±0.5°C; a humidity range of 0-100% RH and an accuracy of ±2% RH; and an MH-Z19B carbon dioxide sensor detects concentrations with a range of 0-5000ppm and an accuracy of ±(50ppm + 3%). The sensor analog signals are converted to digital values via an ADC0832, and the PLC calculates the control variables using a PID algorithm, adjusting the air conditioner compressor frequency (0-50Hz) and the exhaust fan speed (PWM control).

[0082] Data flow: sensor → ADC → PLC → PID algorithm → actuator.

[0083] The temperature and humidity control accuracy reached ±0.5°C / ±1%RH, and the carbon dioxide concentration was maintained below 1000ppm; energy consumption was reduced by 28%, and the failure rate of experimental equipment was reduced by 15%.

[0084] The key system 5 includes:

[0085] The help button and emergency stop button, the signal output end is connected to PLC controller 1;

[0086] When the help button is pressed, the PLC controller 1 sends a help message to the background and records the number of help requests; when the emergency stop button is pressed, the PLC controller 1 immediately triggers an emergency power off and shuts down the dangerous equipment through the execution module 8.

[0087] During specific implementation, the help button is installed at a height of 1.2m, with a laser-engraved help icon on the surface; the emergency stop button is installed in a conspicuous position at the entrance, with yellow warning signs around it. The PLC program sets a help count variable. When a single user requests help ≥ 5 times, it automatically triggers a text message to notify the laboratory administrator.

[0088] Specifically, the help button uses a normally open microswitch with a rated current of 5A / 250VAC. When pressed, it triggers the PLC's I0.0 input. The PLC pushes a help message to the teacher's mobile phone via TCP / IP, in the format: "Laboratory A101 - Zhang San requests help, third time." The emergency stop button uses a mushroom-shaped self-locking pushbutton. When pressed, it disconnects the PLC's 24V power output circuit and triggers a relay to disconnect the main power supply, a 100A air switch.

[0089] Data flow: button → PLC → communication module → teacher terminal.

[0090] This makes the emergency response time less than 100ms and the help information push success rate greater than 99%.

[0091] The human-machine interface 9 integrates six control modules, including personnel management, instrument management, online examination, environmental adjustment, key system 5 and data monitoring interface;

[0092] Through the graphical interactive interface, managers can view laboratory status in real time, remotely control equipment, and generate equipment usage reports and environmental data reports.

[0093] The touchscreen has a resolution of 1024×600 and supports ten-point touch. It also has 4GB of built-in storage, which can locally cache seven days of historical data. The system uses a layered design, with a bottom driver layer responsible for communication, a middle logic layer handling business rules, and an upper interface layer for interaction. Three levels of permissions (administrator / teacher / student) are set, with different function menus displayed for different roles.

[0094] Specifically, the human-machine interface 9 uses MCGS embedded configuration software, communicating with the PLC in real time via the OPC UA protocol. The interface is divided into six functional modules: personnel management (displaying real-time attendance), instrument management (visualizing equipment status), online testing (progress monitoring), environmental adjustment (real-time parameter curves), key system 5 (emergency operation entry), and data monitoring (historical report query). Users trigger corresponding functions by clicking on the touch screen, and the system handles concurrent requests through multi-threading.

[0095] Data flow: user operation → HMI → PLC → subsystem → HMI feedback.

[0096] Supports query of ≥10,000 historical data items; shortens operation training time from 3 days to 4 hours; and reduces management personnel by 50%.

[0097] The execution module 8 is extended to include multimedia equipment and a test bench socket control unit;

[0098] The PLC controller 1 can control the multimedia device switch and the power on and off of the laboratory bench in a coordinated manner. Combined with the RFID instrument management system 3, a coordinated safety mechanism of "instrument access-power activation" is realized.

[0099] During specific implementation, the SSR relay is installed in the distribution box and is installed on a guide rail; the multimedia device is connected to the PLC through an infrared repeater, supports learning remote control coding, and sets the device linkage logic in the PLC program, such as automatically lighting up the corresponding workstation lighting when the microscope is turned on; and automatically saves the multimedia courseware status before turning off the main power.

[0100] Specifically, the PLC controls multimedia devices and lab bench sockets via the EMDR24 expansion module, which features 24 relay outputs. When the RFID system detects the use of an instrument, such as an oscilloscope, the PLC uses a DO output to close the corresponding SSR solid-state relay on the lab bench, rated at 40A, activating the 220V power supply. When the instrument is returned after the experiment, the RFID system sends a signal to the PLC, which then disconnects the power supply after a 10-minute delay to prevent the equipment from running idle.

[0101] Data flow: RFID system → PLC → relay module → power supply equipment.

[0102] This can reduce power switching time, lower standby energy consumption, and reduce the probability of equipment damage due to misoperation.

[0103] The background recording module 7 is built based on blockchain technology and uses a distributed storage method to record information such as personnel entry and exit, instrument use, environmental data, and help records;

[0104] The data cannot be tampered with and is traceable, providing a reliable basis for laboratory safety audits, equipment maintenance and teaching evaluation.

[0105] During the specific implementation, the blockchain node is deployed on a private cloud server with the following configurations: Intel Xeon E5-2620v4×2, 128GB RAM, 1TB SSD, network bandwidth ≥100Mbps, smart contracts are written in Go language, and data access permission control is set; a web front-end interface is developed to support data visualization and audit tracking.

[0106] Specifically, using the Hyperledger Fabric consortium blockchain architecture, laboratory data, such as personnel entry and exit, instrument usage, and environmental parameters, is written to the blockchain via the Node.js SDK. Each block contains the hash value, timestamp, and Merkle tree of the previous block, ensuring data immutability. The consensus mechanism uses PBFT, with validation nodes consisting of the university information center, laboratory management office, and equipment suppliers. Authorized users can query on-chain data via the REST API.

[0107] Data flow: PLC → MQTT Broker → Node.js application → blockchain network → query terminal.

[0108] Finally, a few points should be explained: First, in the description of the present invention, it should be noted that, unless otherwise specified or limited, the terms "mounted", "connected", and "connected" should be understood in a broad sense, and may refer to mechanical or electrical connections, internal communication between two components, or direct connection. "Up", "down", "left", "right", etc. are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may change.

[0109] Secondly: The drawings of the embodiments disclosed in the present invention only involve structures related to the embodiments disclosed in the present invention. Other structures may refer to conventional designs. The same embodiment and different embodiments of the present invention may be combined with each other without conflict.

[0110] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A PLC-based intelligent laboratory management system, characterized by: include: PLC controller (1), serving as the core control unit; An RFID personnel management system (2) is unidirectionally connected to the PLC controller (1) for personnel identification and entry and exit management; An RFID instrument management system (3) is unidirectionally connected to the PLC controller (1) and is used for intelligent access management of experimental instruments; The online examination system (4) is unidirectionally connected to the PLC controller (1) and supports networked examination and anti-cheating functions; An environmental control system (6) is unidirectionally connected to the PLC controller (1) and includes temperature, humidity, and carbon dioxide concentration sensors and an actuator; A key system (5) is unidirectionally connected to the PLC controller (1) and integrates emergency control and help functions; A human-machine interface (9) is bidirectionally connected to the PLC controller (1) and serves as an operation and monitoring interface; The background recording module (7) and the execution module (8) are respectively connected to the PLC controller in a one-way manner for data storage and equipment control.

2. A PLC-based intelligent laboratory management system according to claim 1, characterized in that: The RFID personnel management system (2) comprises: The campus card reading module (21), the campus card information verification module (22) and the campus card information matching module (23) are sequentially connected to form a signal link; The output end of the PLC controller (1) is connected to the access control system, and personnel authority verification is achieved through RFID wireless radio frequency technology. After successful verification, the PLC controller (1) triggers the access control system to open, and the background recording module (7) stores the personnel entry and exit time and the experiment duration.

3. The PLC-based intelligent laboratory management system according to claim 1 is characterized in that: The RFID instrument management system (3) includes: The experimental instrument reading module (31), the experimental instrument verification module (32) and the experimental instrument matching module (33) are connected in sequence to form a signal link; The PLC controller (1) controls the electromagnetic valve of the instrument cabinet through the execution module (8). When the student selects an instrument through the human-machine interface (9), the PLC controller (1) triggers the corresponding instrument cabinet to open. If the instrument is not returned correctly after the experiment, the prompt light of the instrument cabinet automatically lights up to alarm.

4. The PLC-based intelligent laboratory management system according to claim 1 is characterized in that: The online examination system (4) is built using a D1 development board of the ESP8266 module, displays examination information on an LCD display, and communicates bidirectionally with an Internet server; The system supports dynamic IP address allocation and key encryption. Students can access random IP addresses through their mobile phones or computers to obtain test questions. The background can monitor the test status in real time and automatically generate transcripts.

5. The PLC-based intelligent laboratory management system according to claim 1 is characterized in that: The environmental regulation system (6) comprises: The temperature and humidity sensor and the carbon dioxide concentration sensor convert analog signals into digital signals through the A / D conversion module and input them into the PLC controller (1); The PLC controller (1) automatically controls the air conditioner, exhaust fan, lighting, curtains and other equipment in the execution module (8) according to preset thresholds, thereby realizing intelligent adjustment of laboratory environmental parameters.

6. The PLC-based intelligent laboratory management system according to claim 1 is characterized in that: The key system (5) comprises: A help button and an emergency stop button, and a signal output terminal connected to a PLC controller (1); When the help button is pressed, the PLC controller (1) sends a help message to the background and records the number of help requests; when the emergency stop button is pressed, the PLC controller (1) immediately triggers an emergency power off and shuts down the dangerous equipment through the execution module (8).

7. The PLC-based intelligent laboratory management system according to claim 1 is characterized in that: The human-machine interface (9) integrates six control modules, including personnel management, instrument management, online examination, environmental adjustment, key system and data monitoring interface; Through the graphical interactive interface, managers can view laboratory status in real time, remotely control equipment, and generate equipment usage reports and environmental data reports.

8. The PLC-based intelligent laboratory management system according to claim 1 is characterized in that: The execution module (8) is extended to include multimedia equipment and a test bench socket control unit; The PLC controller (1) can control the multimedia device switch and the power on / off of the laboratory bench in a linked manner, and can be combined with the RFID instrument management system (3) to realize the "instrument access-power activation" linkage safety mechanism.

9. The PLC-based intelligent laboratory management system according to claim 1, characterized in that: The background recording module (7) is constructed based on blockchain technology and uses a distributed storage method to record information such as personnel entry and exit, instrument use, environmental data, and help records; The data cannot be tampered with and is traceable, providing a reliable basis for laboratory safety audits, equipment maintenance and teaching evaluation.

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