A meter data collection terminal

Abstract

The utility model discloses a meter data acquisition terminal, including main control module, protocol adaptive switching module, meter interface module and power management module. Protocol adaptive switching module includes protocol detection unit and switching control unit, and protocol detection unit identifies the communication protocol type of connecting to the meter interface through voltage comparator and frequency detection circuit automatically, and switching control unit controls switching switch array according to the identification result, and connects corresponding RS-485 or M-Bus physical layer circuit within 100ms. The utility model discloses through hardware circuit has realized the adaptive identification and switching of communication protocol, and has solved the problem of the numerous kinds, manual configuration and poor reliability of the existing acquisition terminal because of the incompatible protocol with single chip scheme, and has improved the compatibility and deployment efficiency of equipment significantly.

Description

Technical Field

[0001] This utility model relates to a data acquisition terminal, and more particularly to a meter data acquisition terminal. Background Technology

[0002] Currently, with the rapid development of smart cities and the Internet of Things, there is a need for large-scale data collection from various meters deployed in different locations (such as electricity meters, water meters, gas meters, and heat meters). These meters come from different manufacturers and use different communication protocols and physical interface standards, but they mainly focus on the two mainstream protocols: RS-485 and M-Bus.

[0003] In existing technologies, data acquisition terminals typically employ one of two approaches: First, separate hardware interfaces and terminals are designed for different protocols, resulting in a wide variety of devices and high deployment and maintenance costs. Second, manual configuration is performed using jumper caps or DIP switches. This method is not only inefficient but also severely lacks flexibility and convenience in scenarios requiring frequent meter replacement or addition / removal. Especially in large-scale centralized meter reading systems, manual configuration is highly susceptible to communication failures due to human error, making it difficult to guarantee system reliability.

[0004] Therefore, there is an urgent need for a solution that can automatically identify the meter's communication protocol and perform adaptive interface switching. Utility Model Content

[0005] To address the shortcomings of the aforementioned technologies, this utility model provides a meter data acquisition terminal.

[0006] To solve the above technical problems, the technical solution adopted by this utility model is: a meter data acquisition terminal, including a circuit board, characterized in that the circuit board is provided with: The main control module is responsible for data integration, storage, and upload control. The protocol adaptive switching module has its input end connected to the meter interface and its output end connected to the main control module. The meter interface module is controlled by the protocol adaptive switching module and communicates with the main control module. The power management module connects to the main control module, the protocol adaptive switching module, and the meter interface module to provide power to each module. The protocol adaptive switching module includes a protocol detection unit and a switching control unit. The protocol detection unit automatically identifies the communication protocol by monitoring the electrical characteristic signals of the meter interface in real time. The switching control unit controls the switch array inside the meter interface module according to the identification result to connect the physical layer circuit corresponding to the identified protocol.

[0007] Furthermore, the protocol detection unit includes a voltage comparator and a frequency detection circuit. The input of the voltage comparator is connected to the signal line of the meter interface through voltage divider resistors, and its output is connected to the input of the frequency detection circuit. The output of the frequency detection circuit outputs a protocol identification signal to the switching control unit.

[0008] Furthermore, the reference voltage of the voltage comparator is set to 3.3V ± 5%, and the effective identification frequency range of the frequency detection circuit is 1.2kHz to 9.6kHz.

[0009] Furthermore, the switching control unit includes a state machine and a switching switch array. The input of the state machine is connected to the protocol detection unit, and its output controls the conduction path of the switching switch array through a drive circuit.

[0010] Furthermore, the switching time of the switching array K1 is less than 100ms, and the on-resistance is less than 0.5Ω.

[0011] Furthermore, the meter interface module includes an RS-485 interface circuit and an M-Bus slave interface circuit. The RS-485 interface circuit is an RS-485 transceiver chip, and the M-Bus slave interface circuit includes a constant current source transmitting circuit, a switching MOSFET, and a voltage comparison receiving circuit.

[0012] Furthermore, the power management module includes a low-dropout linear regulator and a DC-DC buck-boost converter. The low-dropout linear regulator outputs 3.3V±2% voltage to power the digital circuits, and the DC-DC converter outputs 12V±5% voltage to power the interface circuits.

[0013] This utility model provides a meter data acquisition terminal that solves the problems of insufficient compatibility and a wide variety of equipment. Through the built-in protocol adaptive switching module, a single terminal can automatically identify and adapt to meters using the two mainstream protocols RS-485 and M-Bus, achieving universal compatibility. This fundamentally eliminates the need to equip different terminals for different protocols, greatly simplifies equipment inventory and management, and reduces deployment and maintenance costs.

[0014] This solution addresses the issues of low efficiency and poor reliability associated with manual configuration, achieving full automation of protocol identification and switching. No manual patching, DIP switching, or software configuration is required during on-site installation. This not only reduces configuration time from minutes to seconds, significantly improving installation efficiency, but also completely eliminates communication failures caused by human error, significantly enhancing the overall reliability and stability of the system.

[0015] The intelligence and robustness of the communication connection are enhanced: a fast switching mechanism based on hardware state (switching time <100ms) ensures rapid establishment of the communication link. Simultaneously, during continuous communication, the protocol detection unit can monitor the connection status in real time and automatically re-initiate the detection and connection process when communication is interrupted, giving the terminal intelligent self-recovery capabilities, making it particularly suitable for unattended scenarios requiring long-term stable operation. Attached Figure Description

[0016] Figure 1 This is a block diagram showing the overall system connection of this utility model.

[0017] Figure 2 This is a circuit topology diagram of the protocol detection unit of this utility model.

[0018] Figure 3 This is a circuit topology diagram of the switching control unit of this utility model.

[0019] Figure 4 This is the circuit topology diagram of the M-Bus slave interface of this utility model.

[0020] Figure 5 This is the complete signal flow topology diagram of this utility model.

[0021] In the diagram: 1. Main control module; 2. Protocol adaptive switching module; 3. Meter interface module; 4. Power management module; 21. Protocol detection unit; 22. Switching control unit; 31. RS-485 interface circuit; 32. M-Bus slave interface circuit. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0023] Example 1 (Basic Implementation)

[0024] Reference Figure 1 A meter data acquisition terminal includes a main control module 1, a protocol adaptive switching module 2, a meter interface module 3, and a power management module 4 on its circuit board. The protocol adaptive switching module 2 includes a protocol detection unit 21 and a switching control unit 22. The protocol detection unit 21 automatically identifies the communication protocol by monitoring the electrical characteristic signals of the meter interface J1 in real time. The switching control unit 22 controls the switch array inside the meter interface module 3 according to the identification result to connect the physical layer circuit corresponding to the identified protocol, and executes the protocol detection process and the protocol switching process respectively.

[0025] When a terminal connects to the meter, the protocol adaptive switching module 2 first detects the electrical characteristics of the connected device through the meter interface J1, automatically identifying its communication protocol type (RS-485 or M-Bus). After identification, the switching control unit 22 controls the switch array inside the meter interface module 3 to activate the corresponding physical layer circuit. The main control module 1 establishes communication with the meter through the activated interface circuit, completing data acquisition, processing, and storage. The power management module 4 provides a stable and efficient power supply for each functional module.

[0026] Reference Figure 2 The protocol detection process begins after the protocol detection unit 21 is powered on. The voltage comparator U1A continuously monitors the voltage level of the meter interface J1. When a differential voltage conforming to the RS-485 standard (e.g., greater than ±200mV) or an M-Bus bus voltage (e.g., 12V-42V) is detected, the frequency detection circuit U2 is triggered to analyze the data baud rate characteristics on the signal line. For signals with baud rates in the range of 1.2kbps to 9.6kbps, they are identified as valid meter communication protocols, and the identification result (high / low level signals) is sent to the switching control unit 22.

[0027] Reference Figure 3 The protocol switching process is as follows: after receiving the protocol identification signal, the state machine U3 in the switching control unit 22 makes a judgment within 10ms and controls the conduction path of the switching switch array K1 through the drive circuit Q1. If the protocol is identified as RS-485, the path of RS-485 interface circuit 31 is connected; if the protocol is identified as M-Bus, the path of M-Bus slave interface circuit 32 is connected.

[0028] When the communication protocol type is RS-485 mode, the data is transmitted differentially through RS-485 transceiver U4 and communicates with the UART interface of the main control module 1.

[0029] When the communication protocol type is M-Bus mode, refer to Figure 4 When sending data, the main control module 1 controls the constant current source transmitting circuit U5 and the switching MOSFET MOS1 through the TX pin to send data on the bus with a current change of 1.5mA; when receiving data, the bus voltage is converted into a digital signal by the voltage comparator U6 and transmitted to the main control module 1 through the RX pin.

[0030] In terms of power supply, the DC-DC buck-boost converter U8 in power management module 4 obtains power from an external power source or battery, generating a 12V voltage to mainly power the M-Bus interface circuit. The LDO linear regulator U7 stabilizes the voltage at 3.3V, powering the main control module, protocol detection, and other digital circuits.

[0031] Example 2: Industrial-grade Enhanced Implementation

[0032] This embodiment is optimized for industrial environments to improve reliability and adaptability.

[0033] Protocol detection has been enhanced. The voltage comparator U1A in protocol detection unit 21 adopts a hysteresis comparator design, improving its anti-interference capability to ±500mV. The frequency detection circuit U2 supports an expanded temperature range of -40℃ to 85℃.

[0034] Switching reliability has also been enhanced. The switching array K1 uses optocoupler relays for electrical isolation and can withstand surge voltages up to 1.5kV. The state machine U3 adds timeout and error recovery mechanisms, which can automatically re-initiate the protocol detection process after communication interruption.

[0035] Power management has also been enhanced. Power management module 4 integrates surge protection devices, which can withstand lightning surge impacts as specified in IEC 61000-4-5 standard. The efficiency of DC-DC converter U8 has been optimized to over 92%, reducing overall power consumption.

[0036] The overall system terminal workflow is as follows Figure 5 The terminal's workflow is as follows: In the initial state, after the terminal is powered on, the protocol detection unit 21 continuously monitors the meter interface J1.

[0037] Protocol identification: After the meter is connected, the protocol detection unit 21 completes protocol identification within 500ms.

[0038] Once the pathway is established, the switching control unit 22 completes the physical pathway switching within 100ms.

[0039] Data communication: The main control module 1 exchanges data with the meter through the established communication link.

[0040] During communication, the protocol detection unit 21 continuously monitors the connection status. If a communication interruption is detected, the protocol detection process can be restarted.

[0041] Power management module 4 employs a multi-voltage domain partitioned power supply strategy: the DC-DC buck-boost converter U8 generates a stable 12V±5% voltage from the external power input, primarily providing operating power for the M-Bus interface circuit. The LDO linear regulator U7 outputs a precise 3.3V±2% voltage, providing low-noise power for digital circuits (main control module, protocol detection, etc.).

[0042] To facilitate the implementation of this patent, it should be noted that the circuit connection and operating logic are as follows (but the selection is not limited to this; theoretically, any operating logic of this patent can be implemented):

[0043] The protocol detection unit is the sensing core of the adaptive switching. The signal line of the meter interface J1 is sampled by a voltage divider network consisting of resistors R1 and R2 to ensure that the input voltage is within the common-mode input voltage range of the subsequent comparator U1A. Simultaneously, a simple RC low-pass filter (consisting of resistor R3 and capacitor C1) is used to filter out high-frequency noise. The non-inverting input of comparator U1A is connected to a 3.3V reference voltage generated by a reference voltage source (such as TL431) or a resistor divider. The inverting input is connected to the conditioned signal. When the signal voltage is higher than 3.3V, the output is low; when the signal voltage is pulled low due to current modulation of the RS-485 differential signal or M-Bus communication, the output is high. The comparator output is typically pulled up by a resistor R4 to 10VCC to ensure a standard logic level output.

[0044] The frequency detection circuit U2 can be implemented using a timer / counter peripheral within the main control module 1 combined with a software algorithm. Specifically, the output of comparator U1A is connected to a GPIO pin of the main control module 1 that has input capture functionality. By capturing signal edges and calculating the time interval, the baud rate of the signal can be accurately measured. The identified protocol type (high / low level or specific encoding) is output from another GPIO pin of the main control module 1 to the switching control unit 22.

[0045] After receiving the protocol identification signal, the switching control unit 22 performs a physical path switching. State machine U3 is implemented by the main control module 1 through software logic, or by a small programmable logic device (such as a CPLD). Its input is directly connected to the protocol identification signal line from the protocol detection unit 21. The output GPIO pin of state machine U3 drives a switching circuit composed of a transistor or MOSFET Q1. When the GPIO output is high, Q1 is turned on; when the output is low, Q1 is turned off. The collector / drain of Q1 is connected to the control pin of the switching array K1. The switching array K1 is a multi-channel analog switch integrated circuit (such as CD4053, ADG7 series, etc.), a general-purpose component for signal path switching. Its control terminal is controlled by the output of the drive circuit Q1. Depending on the control level, the common terminal is connected to one of the RS-485 or M-Bus channels. The common terminal of the switch is connected to the meter interface J1, and the two output terminals are connected to the input terminals of the RS-485 interface circuit 31 and the M-Bus slave interface circuit 32, respectively.

[0046] The RS-485 interface circuit 31 is based on a TIA / EIA-485 compliant RS-485 transceiver chip U4 (such as SN65HVD72, MAX3485, etc.). The RO (receive output) and DI (transmit input) pins of U4 are directly connected to the UART interface of the main control module 1. The RE# (receive enable) and DE (transmit enable) pins of U4 are controlled by another GPIO of the main control module 1 to switch the transmit and receive states; this is a common configuration for RS-485 half-duplex communication. A 120Ω terminating resistor R5 is connected in parallel between the A and B signal lines, and a small-value resistor (such as 22Ω) is connected in series on the A and B lines, followed by a TVS diode (such as SMBJ6.5CA) in parallel for impedance matching and surge protection.

[0047] The M-Bus slave interface circuit 32 employs a constant current source transmitting circuit, consisting of an operational amplifier U5 (such as LM358) and a MOSFET (MOS1) forming a classic constant current source circuit. The TX signal of the master control module 1 is connected to the non-inverting input of U5. By controlling the output voltage of U5, the current flowing through MOS1 and the meter interface J1 (typically 1.5mA) is precisely controlled to achieve data transmission.

[0048] The voltage comparison and receiving circuit consists of a voltage comparator U6 (such as LM393). The voltage signal on the M-Bus bus is level-shifted through a resistor divider network R6 and R7 and sent to the inverting input of U6. It is compared with the reference voltage at the non-inverting input, converting the bus voltage change into a digital signal, which is then sent back to the main control module 1 through the RX pin.

[0049] The power extraction circuit acts as a slave device, requiring the terminal to draw power from the M-Bus bus. This general-purpose circuit includes a full-bridge rectifier circuit (composed of diodes D1-D4) to prevent reverse power connection, and a linear regulator (LDO) or DC-DC converter to stably convert the bus voltage (12-42V) to the voltage required internally by the terminal (such as 3.3V or 5V).

[0050] The DC-DC buck-boost converter U8 in power management module 4 connects to an external power supply at its input. Internally, it integrates a power inductor, a switching transistor, and a freewheeling diode, and outputs a stable 12V voltage through a feedback resistor network. Its output typically uses a large-value electrolytic capacitor and a small-value ceramic capacitor in parallel for decoupling and filtering.

[0051] The low-dropout linear regulator U7 connects to a 12V DC-DC output or a battery at its input, providing a stable, low-noise 3.3V output. Decoupling capacitors are also required in parallel at both the input and output to suppress power supply ripple.

[0052] The above embodiments are not intended to limit the present utility model, nor is the present utility model limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the technical solution of the present utility model are also within the protection scope of the present utility model.

Claims

1. A meter data acquisition terminal, comprising a circuit board, characterized in that, The circuit board is equipped with: The main control module (1) is responsible for data integration, storage and upload control; The protocol adaptive switching module (2) has its input end connected to the meter interface J1 and its output end connected to the main control module (1). The meter interface module (3) is controlled by the protocol adaptive switching module (2) and communicates with the main control module (1); The power management module (4) connects to the main control module (1), the protocol adaptive switching module (2), and the meter interface module (3) to supply power to each module; The protocol adaptive switching module (2) includes a protocol detection unit (21) and a switching control unit (22). The protocol detection unit (21) automatically identifies the communication protocol by monitoring the electrical characteristic signals of the meter interface J1 in real time. The switching control unit (22) controls the switch array inside the meter interface module (3) according to the identification result to connect the physical layer circuit corresponding to the identified protocol.

2. The meter data acquisition terminal according to claim 1, characterized in that: The protocol detection unit (21) includes a voltage comparator U1A and a frequency detection circuit U2. The input terminal of the voltage comparator U1A is connected to the signal line of the meter interface J1 through voltage divider resistors R1 and R2. Its output terminal is connected to the input terminal of the frequency detection circuit U2. The output terminal of the frequency detection circuit U2 outputs a protocol identification signal to the switching control unit (22).

3. The meter data acquisition terminal according to claim 2, characterized in that: The reference voltage of the voltage comparator U1A is set to 3.3V±5%, and the effective identification frequency range of the frequency detection circuit U2 is 1.2kHz to 9.6kHz.

4. The meter data acquisition terminal according to claim 1, characterized in that: The switching control unit (22) includes a state machine U3 and a switching array K1. The input of the state machine U3 is connected to the protocol detection unit (21), and its output controls the conduction path of the switching array K1 through the drive circuit Q1.

5. The meter data acquisition terminal according to claim 4, characterized in that: The switching time of the switching array K1 is less than 100ms and the on-resistance is less than 0.5Ω.

6. The meter data acquisition terminal according to claim 1, characterized in that: The meter interface module (3) includes an RS-485 interface circuit (31) and an M-Bus slave interface circuit (32). The RS-485 interface circuit (31) is an RS-485 transceiver chip U4. The M-Bus slave interface circuit (32) includes a constant current source transmitting circuit U5, a switching MOS transistor MOS1, and a voltage comparison receiving circuit U6.

7. The meter data acquisition terminal according to claim 1, characterized in that: The power management module (4) includes a low-dropout linear regulator U7 and a DC-DC buck-boost converter U8. The low-dropout linear regulator U7 outputs 3.3V±2% voltage to power the digital circuit, and the DC-DC buck-boost converter U8 outputs 12V±5% voltage to power the interface circuit.

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