Air source heat pump master control serial port communication converter board and control system

Abstract

The invention discloses an air source heat pump master control serial port communication converter board, which comprises a master controller, a serial port module, a MODBUS module and a power supply module, and is characterized in that the master controller communicates with external equipment and the MODBUS module through the serial port module, integrates a plurality of serial ports and ADC interfaces, and realizes conversion of various serial port protocols, environmental parameter acquisition and data processing; the serial port module comprises at least two paths of serial port interfaces with different standards and is used for connecting a superior control unit, a touch panel or other external equipment; the MODBUS module supports a wireless communication protocol and is internally provided with a TCP / IP (Transmission Control Protocol / Internet Protocol) stack to realize remote data interaction with an upper end; the main controller collects operation state parameters detected by an external sensor through the DMA channel, and the operation state parameters are transmitted to an upper end through the serial port module or the MODBUS module after being operated, stored and verified. The technical problem that conversion between different communication protocols in the air source heat pump system is difficult is solved, and system compatibility and communication reliability are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of communication conversion boards, and in particular to an air source heat pump main control serial port communication conversion board and a control system. Background Art

[0002] With the widespread adoption of air-source heat pump technology in building energy conservation and environmental protection, communication stability and compatibility issues within its control systems have become increasingly prominent. Air-source heat pump systems typically consist of a main control board, a sensor network, and a higher-level control unit. These devices require real-time data exchange to ensure efficient operation. However, due to the varying communication protocols and interface standards used by these devices, achieving seamless communication between them has become a technical challenge.

[0003] Currently, commonly used communication interfaces in the industrial field mainly include RS-232, RS-485, and Ethernet. However, various components in air-source heat pump systems may adopt different communication standards. For example, CN108090005A discloses a four-serial port server, which includes two RS232 interfaces, two RS485 interfaces, network interface circuitry, serial port processing circuitry, and a main controller. It can perform signal conversion between Ethernet and serial port protocols. Although this design realizes dual RS232 and dual RS485 interface connections, it lacks specific optimization for air-source heat pump systems and cannot meet the special requirements of heat pump control systems for real-time performance and stability.

[0004] In the field of multifunctional communication conversion, CN110262989B proposes a communication converter comprising a network module, a main controller, a power module, and multiple serial port signal conversion circuits. This converter communicates with a host computer via the network module. The main controller is equipped with multiple serial ports, each of which communicates with a device via a serial port signal conversion circuit. While this design enables transparent data transmission between the host computer and the device, it has limitations in handling the collection and processing of multiple environmental parameters in air source heat pump systems.

[0005] CN110147339A discloses a device control device for communication conversion based on a wireless router. The device includes a network port to serial port module, an RS232 conversion circuit, a wireless router, a power supply module, and an STM32 control system. The device uses the wireless router to interconnect RS232 communication devices and terminals, and can convert serial port information into digital information. However, the device fails to fully consider electromagnetic interference in industrial environments, resulting in insufficient anti-interference capabilities and difficulty ensuring reliable data transmission.

[0006] Regarding RFID data compatibility conversion, CN113886301A proposes a multi-serial port, multi-protocol RFID data compatibility conversion method, using a single-chip microcontroller integrated with multiple communication protocols to control multiple serial ports. While this method achieves multi-serial port, multi-protocol data compatibility conversion, it is not optimized for the specific needs of air-source heat pump systems and cannot meet the requirements of heat pump control systems for real-time collection and processing of environmental parameters.

[0007] Recently, CN115941813A disclosed a communication method specifically for air-source heat pumps. This method, through a data acquisition module, enables an application platform to communicate with air-source heat pumps using different communication protocols. While this method solves the protocol adaptation issue, it still suffers from high power consumption and a lack of intelligent control capabilities, limiting the operational flexibility and management efficiency of the equipment.

[0008] Existing technologies have the following shortcomings: First, the main control motherboard of an air-source heat pump typically only supports a limited number of serial port outputs, making it impossible to directly implement multi-protocol communication with the upper control unit; second, existing serial port protocol conversion methods often require conversion one by one, which is inefficient; third, electromagnetic interference in industrial environments seriously affects the stability of data communication, and existing conversion devices lack anti-interference capabilities; fourth, existing communication conversion devices generally have high power consumption, which reduces the device's service life; finally, existing technologies lack intelligent control functions, making it impossible to achieve remote management and automated data transmission, limiting the device's operational flexibility and management efficiency. Therefore, there is an urgent need to develop a communication conversion board specifically for air-source heat pump systems that can implement multiple serial port protocol conversions and has the ability to collect environmental parameters and process data. Summary of the Invention

[0009] In order to solve the problem of communication protocol conversion of the main control motherboard of the air source heat pump and realize efficient conversion and stable communication between multiple serial port protocols, the present invention provides an air source heat pump main control serial port communication conversion board.

[0010] The technical implementation scheme of the present invention is: A main control serial communication conversion board for an air source heat pump comprises: a main controller configured to communicate with external devices and a MODBUS module via a serial port module, the main controller integrating multiple serial ports and ADC interfaces for implementing conversion of multiple serial port protocols, environmental parameter acquisition and data processing; a serial port module comprising at least two serial port interfaces of different standards for connecting to a superior control unit, a touch panel or other external devices; a MODBUS module communicating with the main controller, supporting wireless communication protocols and having a built-in TCP / IP protocol stack for implementing remote data interaction with a host end; a power supply module configured to provide operating voltage to the main controller, the MODBUS module and external sensors; the main controller acquiring operating status parameters detected by external sensors via a DMA channel, and transmitting the parameters to the host end via the serial port module or the MODBUS module after calculation, storage and verification, thereby implementing signal conversion, isolation and data transparent transmission.

[0011] Optionally, the serial port module includes an RS-232 interface and an RS-485 interface, wherein one serial port uses the RS-232 standard to communicate with the upper control unit, and the other uses the RS-485 standard to communicate with the touch panel or other devices.

[0012] Optionally, the MODBUS module uses a wireless communication chip that supports 802.11b / g / n / ac standards, has STA / AP / STA+AP working modes, is connected to the main controller through a serial port or GPIO interface, and supports remote firmware upgrade function.

[0013] Optionally, the power module includes a step-down circuit, which converts 5V DC power into 3.3V through an ASM117 chip to power the main controller, MODBUS module and external sensors.

[0014] Optionally, an alarm module is further included, which is connected to the main controller and sends an alarm message to an upstream terminal via a buzzer, LED or serial port when the operating status parameter exceeds a preset threshold.

[0015] Optionally, the external sensor includes at least one of a temperature sensor, a humidity sensor, a power sensor and a power sensor, which is connected to the main controller via a serial port or an I2C bus to collect environmental parameters of the air source heat pump system in real time.

[0016] Optionally, the main controller adopts an STM32 series single-chip microcomputer, is equipped with a DMA module for data acquisition and transmission, supports initialization and configuration of the MODBUS module through AT instructions, and establishes a communication link with the upper end.

[0017] An air source heat pump control system comprises a communication conversion board, an air source heat pump main control board, and a host terminal. The communication conversion board is connected to the air source heat pump main control board via an RS-232 interface and communicates with the host terminal via a MODBUS module or a serial port module, thereby enabling multi-protocol data interaction between the upper control unit and the air source heat pump system.

[0018] The present invention has the following advantages: 1. The present invention realizes conversion between multiple serial port protocols, overcomes the limitation of the existing technology that requires conversion one by one, significantly improves conversion efficiency, and meets the communication needs in complex industrial environments.

[0019] 2. Sensor data is collected through DMA and sent to the host platform through the serial port, realizing signal conversion, isolation and data transparent transmission, effectively solving the communication protocol incompatibility problem existing in the air source heat pump main control system.

[0020] 3. Set the threshold to alarm the data. When the parameter value exceeds the set threshold, the main controller will control the alarm module to issue the corresponding alarm information, realizing the intelligent control function and improving the system's remote management and automated data transmission capabilities.

[0021] 4. Adopt multiple communication interfaces, including RS-232 and RS-485 standards, to achieve communication with different types of equipment, effectively extend the communication distance, and improve the overall performance and flexibility of the system.

[0022] 5. Through optimized hardware circuit design and software algorithms, the system's anti-interference capability is significantly improved, ensuring the stability and reliability of data transmission and solving the problem of electromagnetic interference affecting communications in industrial environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the main block diagram of the present invention.

[0024] Figure 2 This is the circuit diagram of the modbus module of the present invention.

[0025] Figure 3 This is the circuit diagram of the alarm module of the present invention.

[0026] Figure 4 This is a schematic diagram of the power module part of the present invention.

[0027] Figure 5 It is the overall program flow chart of the present invention. DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions, and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings. It is hereby stated that any directional terms such as "up," "down," "left," "right," "front," "back," "inside," and "outside" that appear or will appear herein are based solely on the accompanying drawings and are not intended to limit the present invention. Example

[0029] A main control serial port communication conversion board for an air source heat pump comprises a main controller, a serial port module, a MODBUS module and a power supply module.

[0030] The main controller uses an STM32F103 series microcontroller, which integrates three UART serial ports and a 12-bit ADC interface for converting multiple serial protocols, collecting environmental parameters, and processing data. The main controller integrates a 72MHz ARM Cortex-M3 core, 64KB of flash memory, and 20KB of SRAM, meeting the needs of complex communication protocol conversion and data processing. The main controller communicates with external devices and the MODBUS module via a serial port module, enabling data reception, processing, and forwarding.

[0031] The serial port module includes two serial interfaces of different standards: RS-232 and RS-485. The RS-232 interface uses the MAX3232 chip for level conversion, featuring ±15kV ESD protection and high reliability. It is used for connecting to the upper control unit of the air-source heat pump. The RS-485 interface uses the MAX485 chip for differential signal transmission, offering strong anti-interference capabilities and a transmission distance of up to 1200 meters. It is used for connecting to touch panels or other external devices. Both serial ports are equipped with TVS diode protection circuits to effectively prevent damage to the communication converter board due to static electricity and surges.

[0032] The MODBUS module uses the ESP8266 wireless communication chip, which supports 802.11b / g / n wireless communication standards, a built-in TCP / IP protocol stack, and three operating modes: STA / AP / STA+AP. The MODBUS module connects to the host controller via a UART serial port, with a configurable baud rate between 9600bps and 115200bps. It supports both MODBUS-RTU and MODBUS-TCP protocols for remote data exchange with the host. The module also supports remote firmware upgrades, facilitating system maintenance and functionality expansion.

[0033] The power module includes a step-down circuit that converts 5V DC power to 3.3V using an ASM117 chip to power the main controller, MODBUS module, and external sensors. The ASM117 chip features a low voltage dropout of only 1.3V at high current output, achieving a conversion efficiency of up to 80%. The power module also features a multi-stage filter circuit, including a 10μF electrolytic capacitor on the input and a 22μF tantalum capacitor on the output, to effectively suppress power ripple and ensure stable system operation.

[0034] The communication converter board also includes external sensor interfaces for connecting temperature, humidity, power, and power sensors. The temperature sensor uses a DS18B20 digital temperature sensor with a measurement range of -55°C to +125°C and an accuracy of ±0.5°C. The humidity sensor uses a DHT22 with a measurement range of 0-100%RH and an accuracy of ±2%RH. The power sensor uses an ACS712 current sensor with a range of ±5A and an accuracy of ±1.5%. The power sensor uses the HLW8012 chip, which can simultaneously measure voltage, current, and power. These sensors connect to the main controller via a serial port or I2C bus to collect real-time environmental parameters from the air source heat pump system.

[0035] The communication converter board also features an alarm module, including a buzzer and LED indicators. The buzzer is active, operating at 3.3V and with a sound pressure level greater than 85dB. The LED indicators include a power indicator, a communication status indicator, and an alarm indicator, represented by green, blue, and red LEDs, respectively. When system operating parameters exceed preset thresholds, the alarm module sounds an audible alarm through the buzzer, illuminates the red LED, and sends an alarm message to the upstream terminal via the serial port.

[0036] The main controller uses DMA channels to collect operating status parameters detected by external sensors, completing data transmission without CPU intervention, thereby improving system efficiency. The collected data undergoes computational processing by the main controller, including filtering, calibration, and data format conversion. It is then stored in Flash or EEPROM and subjected to a CRC check to ensure data integrity. The processed data is then transmitted to the host via a serial port module or MODBUS module, enabling signal conversion, isolation, and data transparent transmission.

[0037] In actual applications, the communication conversion board connects to the air source heat pump's upper control unit via an RS-232 interface to receive control commands and status query requests; connects to the touch panel via an RS-485 interface to implement human-computer interaction; and establishes a wireless connection with the upper end via a MODBUS module for remote monitoring and data analysis. The main controller performs protocol conversion and data format adaptation based on the characteristics of different communication protocols to ensure seamless communication between devices.

[0038] The main controller uses an STM32 series microcontroller and is equipped with a DMA module for data acquisition and transmission. The DMA module contains seven channels with independently configurable priority and transfer mode, supporting memory-to-memory, peripheral-to-memory, and memory-to-peripheral transfer modes. The main controller initializes and configures the MODBUS module using AT commands. The AT command set includes basic AT commands, Wi-Fi-related AT commands, and TCP / IP-related AT commands. These commands are used to set the module's operating mode, connection parameters, and communication parameters, and to establish a communication link with the host. Example

[0039] A main control serial port communication conversion board for an air source heat pump comprises a main controller, a serial port module, a MODBUS module and a power supply module.

[0040] The main controller uses an STM32F407 series microcontroller, which integrates six UART serial ports and a 12-bit ADC interface. This allows for conversion of multiple serial protocols, environmental parameter acquisition, and data processing. The main controller integrates a 168MHz ARM Cortex-M4 core, 1MB of flash memory, and 192KB of SRAM, meeting the requirements of complex communication protocol conversion and data processing. The main controller communicates with external devices and the MODBUS module via a serial port module, enabling data reception, processing, and forwarding.

[0041] The serial port module includes both RS-232 and RS-485 interfaces. One serial port uses the RS-232 standard to communicate with the upper-level control unit, while the other uses the RS-485 standard to communicate with the touch panel or other devices. The RS-232 interface uses the SP3232 chip for level conversion, featuring ±15kV ESD protection and high reliability. The RS-485 interface uses the SP485 chip for differential signal transmission, offering strong anti-interference capabilities and a transmission distance of up to 1200 meters. Both serial ports are equipped with TVS diode protection circuits to effectively prevent damage to the communication converter board from static electricity and surges.

[0042] The MODBUS module uses the ESP32 wireless communication chip, which supports 802.11b / g / n / ac wireless communication standards, a built-in TCP / IP protocol stack, and three operating modes: STA / AP / STA+AP. The MODBUS module connects to the host controller via a UART serial port, with a configurable baud rate between 9600bps and 921600bps. It supports both MODBUS-RTU and MODBUS-TCP protocols for remote data exchange with the host. The module also supports remote firmware upgrades, facilitating system maintenance and functionality expansion.

[0043] The power module includes a step-down circuit that converts 5V DC power to 3.3V using an ASM117 chip to power the main controller, MODBUS module, and external sensors. The ASM117 chip features a low voltage dropout of only 1.3V at high current output, achieving a conversion efficiency of up to 80%. The power module also features a multi-stage filtering circuit, including a 10μF electrolytic capacitor on the input and a 22μF tantalum capacitor on the output, to effectively suppress power ripple and ensure stable system operation.

[0044] The communication conversion board also includes an alarm module, which is connected to the main controller. When operating parameters exceed preset thresholds, it sends an alarm message to the upstream terminal via a buzzer, LED, or serial port. The buzzer is an active buzzer with an operating voltage of 3.3V and a sound pressure level greater than 85dB. LED indicators include a power indicator (green), a communication status indicator (blue), and an alarm indicator (red). The alarm module also includes a relay output interface that can be connected to external alarm devices or actuators to implement coordinated control functions.

[0045] The communication converter board also features external sensor interfaces for connecting temperature, humidity, power, and power sensors. The temperature sensor uses a PT100 platinum resistor with a measurement range of -200°C to +850°C and an accuracy of ±0.1°C. The humidity sensor uses an SHT30 with a measurement range of 0-100%RH and an accuracy of ±2%RH. The power sensor uses an ACS758 current sensor with a range of ±50A and an accuracy of ±1%. The power sensor uses an ATM90E36 chip, which can simultaneously measure voltage, current, and power with an accuracy of 0.1. These sensors connect to the main controller via a serial port or I2C bus to collect real-time environmental parameters from the air source heat pump system.

[0046] The main controller uses DMA channels to collect operating status parameters detected by external sensors, completing data transmission without CPU intervention, thereby improving system efficiency. The collected data undergoes computational processing by the main controller, including filtering, calibration, and data format conversion. It is then stored in Flash or EEPROM and subjected to a CRC check to ensure data integrity. The processed data is then transmitted to the host via a serial port module or MODBUS module, enabling signal conversion, isolation, and data transparent transmission.

[0047] In actual applications, the communication conversion board connects to the air source heat pump's upper control unit via an RS-232 interface to receive control commands and status query requests; connects to the touch panel via an RS-485 interface to implement human-computer interaction; and establishes a wireless connection with the upper end via a MODBUS module for remote monitoring and data analysis. The main controller performs protocol conversion and data format adaptation based on the characteristics of different communication protocols to ensure seamless communication between devices.

[0048] The main controller uses an STM32 series microcontroller and is equipped with a DMA module for data acquisition and transmission. The DMA module contains 16 channels with independently configurable priority and transfer mode, supporting memory-to-memory, peripheral-to-memory, and memory-to-peripheral transfer modes. The main controller initializes and configures the MODBUS module using AT commands. The AT command set includes basic AT commands, Wi-Fi-related AT commands, and TCP / IP-related AT commands. These commands are used to set the module's operating mode, connection parameters, and communication parameters, and to establish a communication link with the host. Example

[0049] An air source heat pump control system comprises a communication conversion board, an air source heat pump main control board and a host terminal.

[0050] The communication conversion board includes a main controller, serial port module, MODBUS module, and power module. The main controller uses an STM32F103 series microcontroller, which integrates three UART serial ports and a 12-bit ADC interface. This allows for conversion of multiple serial protocols, environmental parameter collection, and data processing. The main controller integrates a 72MHz ARM Cortex-M3 core, 64KB of flash memory, and 20KB of SRAM, meeting the needs of complex communication protocol conversion and data processing.

[0051] The serial port module includes both RS-232 and RS-485 interfaces. The RS-232 interface uses a MAX3232 chip for level conversion and is used to connect to the air-source heat pump main control board. The RS-485 interface uses a MAX485 chip for differential signal transmission and is used to connect to the touch panel or other external devices. Both serial ports are equipped with TVS diode protection circuits to effectively prevent damage to the communication converter board due to static electricity and surges.

[0052] The MODBUS module uses the ESP8266 wireless communication chip, which supports 802.11b / g / n wireless communication standards, a built-in TCP / IP protocol stack, and three operating modes: STA / AP / STA+AP. The MODBUS module connects to the host controller via a UART serial port and supports both MODBUS-RTU and MODBUS-TCP protocols, enabling remote data exchange with the host.

[0053] The power module includes a step-down circuit that converts 5V DC power to 3.3V using an ASM117 chip to power the main controller, MODBUS module, and external sensors. The power module also features a multi-stage filter circuit, including a 10μF electrolytic capacitor on the input and a 22μF tantalum capacitor on the output, to effectively suppress power ripple and ensure stable system operation.

[0054] The communication converter board also includes external sensor interfaces for connecting temperature sensors, humidity sensors, power sensors, and power sensors. These sensors are connected to the main controller via a serial port or I2C bus to collect real-time environmental parameters of the air source heat pump system.

[0055] The communication converter board is also equipped with an alarm module, including a buzzer and LED indicator. When the system operating status parameters exceed the preset threshold, the alarm module sounds an audible alarm through the buzzer, lights up the red LED indicator, and sends an alarm message to the upstream terminal through the serial port.

[0056] The air-source heat pump's main control board is the core control unit of the entire heat pump system, responsible for controlling the operation of actuators such as the compressor, fan, four-way valve, and electronic expansion valve. The main control board utilizes a 32-bit microprocessor and integrates multiple analog and digital input and output interfaces for collecting system operating parameters and controlling various actuators. The main control board connects to the communication converter board via an RS-232 interface for data exchange and command transmission.

[0057] The host end includes a monitoring server and client application. The monitoring server uses the Linux operating system and is equipped with a MySQL database and web server for data storage, processing, and display. The client application includes PC management software and a mobile app, supporting multi-platform access and operation. The host end communicates with the communication converter board via a MODBUS module or serial port module, enabling remote monitoring, parameter setting, and fault diagnosis of the air source heat pump system.

[0058] In this control system, the communication conversion board connects to the air-source heat pump main control board via an RS-232 interface, receiving operating status data and fault information from the main control board and simultaneously transmitting control commands from the host to the main control board. A wireless connection with the host is established via a MODBUS module, enabling remote data exchange. The main controller performs protocol conversion and data format adaptation based on the characteristics of different communication protocols, ensuring seamless communication between devices.

[0059] The main controller collects operating status parameters detected by external sensors through DMA channels. After calculation, storage, and verification, it is transmitted to the host through the serial port module or MODBUS module, realizing signal conversion, isolation, and data transparent transmission. After receiving the data, the host terminal stores, analyzes, and displays it, providing users with intuitive system operating status information and decision support.

[0060] This control system enables multi-protocol data exchange between the upper-level control unit and the air-source heat pump system, resolving compatibility issues between different communication protocols and improving system interoperability and scalability. Wireless communication technology enables remote monitoring and control, allowing users to monitor system operating status and make necessary adjustments anytime, anywhere, improving system manageability and user experience.

[0061] It should be noted that the first, second and third embodiments are all a type of serial port protocol-based communication conversion board used for communication with the upper control unit of the air source heat pump.

[0062] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge of those skilled in the art without departing from the spirit of the present invention.

Claims

1. An air source heat pump main control serial port communication conversion board, characterized in that: include: A main controller configured to communicate with external devices and a MODBUS module via a serial port module. The main controller is integrated with multiple serial ports and ADC interfaces for implementing conversion of multiple serial port protocols, environmental parameter collection, and data processing. Serial port module, including at least two serial port interfaces of different standards, used to connect to the upper control unit, touch panel or other external devices; The MODBUS module is connected to the main controller, supports wireless communication protocols and has a built-in TCP / IP protocol stack for remote data interaction with the upper end; a power module configured to provide operating voltage to the main controller, the MODBUS module and the external sensor; The main controller collects the operating status parameters detected by the external sensor through the DMA channel, and transmits them to the upper end through the serial port module or MODBUS module after calculation, storage and verification, thereby realizing signal conversion, isolation and data transparent transmission.

2. The air source heat pump master serial communication conversion board according to claim 1, characterized in that: The serial port module includes an RS-232 interface and an RS-485 interface. One serial port uses the RS-232 standard to communicate with the upper control unit, and the other uses the RS-485 standard to communicate with the touch panel or other devices.

3. The air source heat pump master serial communication conversion board according to claim 1, characterized in that: The MODBUS module uses a wireless communication chip that supports 802.11b / g / n / ac standards, has STA / AP / STA+AP working modes, is connected to the main controller through the serial port or GPIO interface, and supports remote firmware upgrade function.

4. The air source heat pump master serial communication conversion board according to claim 1, characterized in that: The power module includes a step-down circuit that converts 5V DC power to 3.3V through the ASM117 chip to power the main controller, MODBUS module and external sensors.

5. The air source heat pump master serial communication conversion board according to claim 1, characterized in that: The system also includes an alarm module, which is connected to the main controller and sends an alarm message to an upper terminal via a buzzer, LED or serial port when the operating state parameter exceeds a preset threshold.

6. The air source heat pump master serial communication conversion board according to claim 1, characterized in that: The external sensor includes at least one of a temperature sensor, a humidity sensor, a power sensor and a power sensor, which is connected to the main controller via a serial port or an I2C bus and is used to collect environmental parameters of the air source heat pump system in real time.

7. The air source heat pump master serial communication conversion board according to claim 1, characterized in that: The main controller adopts STM32 series single chip microcomputer, equipped with DMA module for data acquisition and transmission, supports initialization and configuration of MODBUS module through AT instructions, and establishes a communication link with the upper end.

8. An air source heat pump control system, characterized in that: It includes a communication conversion board, an air source heat pump main control board and an upper end as described in any one of claims 1 to 7, wherein the communication conversion board is connected to the air source heat pump main control board through an RS-232 interface, and communicates with the upper end through a MODBUS module or a serial port module to realize multi-protocol data interaction between the upper control unit and the air source heat pump system.

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