Communication circuit of multiplexing port and electric energy meter
By constructing a data transmission channel for MBUS and RS485 communication in the energy meter, and using an optocoupler to multiplex the UART port, the problem of mismatched UART port numbers is solved, design costs and space are reduced, and economic efficiency is improved.
Patent Information
- Application Number
- CN202520443108.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-13
- Publication Date
- 2026-01-06
- Estimated Expiration
- 2035-03-13
Smart Images
Figure CN223770572U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of communication technology, and in particular to a communication circuit and energy meter with multiplexed ports. Background Technology
[0002] In the field of electricity meters, the microcontroller unit (MCU) in the meter is connected to the internal functional circuits of the meter through its own UART port, thereby ensuring that the meter can perform different functions. However, when designing an electricity meter, design cost, design cycle, development cycle, etc. need to be considered. Therefore, there is a certain requirement for the number of UART ports corresponding to the MCU in the electricity meter.
[0003] In recent years, customers have increasingly higher requirements for electricity meters, hoping to implement MBUS and RS485 communication functions. However, due to the limited number of UART ports corresponding to the MCU in the electricity meter, a mismatch easily arises between the number of UART ports and the number of functions the meter needs to implement. In other words, MBUS and RS485 communication functions may each be assigned to a single UART port. Currently, UART port multiplexing is commonly used to address this issue. Figure 1 As shown. However Figure 1 In the structure shown, MBUS communication and RS485 communication correspond to two communication circuits respectively. In order to ensure stable signal transmission, each communication circuit includes an optocoupler, which increases the design cost and design space. Utility Model Content
[0004] The purpose of this invention is to provide a communication circuit and energy meter with a multiplexed port, which can realize two communication modes by using two data transmission channels constructed by a first isolation circuit, a second isolation circuit and a conversion circuit. This reduces the design space of the communication circuit with the multiplexed port. Furthermore, the design of the first isolation circuit and the second isolation circuit each use an optocoupler, which reduces the overall number of optocouplers used, thereby reducing the design cost and improving the economy of related electronic equipment.
[0005] To solve the above-mentioned technical problems, this utility model provides a communication circuit with multiplexed ports, including: a conversion circuit, a first isolation circuit, and a second isolation circuit, wherein both the first isolation circuit and the second isolation circuit include an optocoupler;
[0006] The input terminal of the first isolation circuit is connected to the output terminal of the microcontroller unit, the output terminal of the first isolation circuit is connected to the input terminal of the RS485 circuit and the first terminal of the conversion circuit, the input terminal of the second isolation circuit is connected to the output terminal of the RS485 circuit, and the output terminal of the second isolation circuit is connected to the input terminal of the microcontroller unit. When the microcontroller unit is in RS485 communication mode, communication between the microcontroller unit and the RS485 circuit is realized through the data transmission channel formed by the first isolation circuit and the data reception channel formed by the second isolation circuit.
[0007] The second terminal of the conversion circuit is connected to the input terminal of the MBUS circuit, and the input terminal of the second isolation circuit is connected to the output terminal of the MBUS circuit. When the microcontroller is in MBUS communication mode, communication between the microcontroller and the MBUS circuit is achieved through the data transmission channel formed by the first isolation circuit and the conversion circuit and the data reception channel formed by the second isolation circuit.
[0008] Optionally, the conversion circuit includes a first resistor and a first transistor;
[0009] The first end of the first resistor is connected to the output of the first isolation circuit and the input of the RS485 circuit as the first end of the conversion circuit, and the second end of the first resistor is connected to the base of the first transistor.
[0010] The emitter of the first transistor is grounded, and the collector of the first transistor is connected to the input terminal of the MBUS circuit as the second terminal of the switching circuit.
[0011] Optionally, the first isolation circuit includes a first optocoupler isolation acceleration circuit and an inverting control circuit, wherein the first optocoupler isolation acceleration circuit is provided with an optocoupler;
[0012] The input terminal of the first optocoupler isolation acceleration circuit is connected to the output terminal of the microcontroller unit as the input terminal of the first isolation circuit. The output terminal of the first optocoupler isolation acceleration circuit and the output terminal of the inverting control circuit are used together as the output terminal of the first isolation circuit.
[0013] The output of the first optocoupler isolation acceleration circuit is connected to the input of the inverting control circuit and the input of the RS485 circuit.
[0014] The output of the inverting control circuit is connected to the enable terminal of the RS485 circuit and the first terminal of the conversion circuit.
[0015] Optionally, the optocoupler in the first optocoupler acceleration circuit is a first optocoupler, and the first optocoupler acceleration circuit further includes: a second resistor, a third resistor, a first capacitor, a fourth resistor, and a second transistor.
[0016] The first pin of the first optocoupler is connected to the first power supply voltage via the second resistor. The second pin of the first optocoupler is connected to the output terminal of the microcontroller unit as the input terminal of the first optocoupler isolation acceleration circuit. The third pin of the first optocoupler is connected to the first terminal of the third resistor, the first terminal of the first capacitor, and the first terminal of the fourth resistor. The fourth pin of the first optocoupler is connected to the second power supply voltage.
[0017] The second terminal of the third resistor is connected to the second terminal of the first capacitor and the base of the second transistor;
[0018] The second terminal of the fourth resistor and the emitter of the second transistor are both grounded;
[0019] The collector of the second transistor is connected to the output of the first optocoupler isolation acceleration circuit, the input of the inverting control circuit, and the input of the RS485 circuit.
[0020] Optionally, the inverting control circuit includes a fifth resistor, a third transistor, a second capacitor, and a sixth resistor;
[0021] The first end of the fifth resistor is connected to the input of the inverting control circuit, the output of the first optocoupler isolation acceleration circuit, and the input of the RS485 circuit. The second end of the fifth resistor is connected to the base of the third transistor.
[0022] The emitter of the third transistor is connected to the second power supply voltage. The collector of the third transistor, the first terminal of the second capacitor, and the first terminal of the sixth resistor together serve as the output terminal of the inverting control circuit, which is connected to the enable terminal of the RS485 circuit and the first terminal of the conversion circuit.
[0023] The second terminal of the second capacitor and the second terminal of the sixth resistor are both grounded.
[0024] Optionally, the optocoupler in the second isolation circuit is a second optocoupler, and the second isolation circuit also includes a seventh resistor, an eighth resistor, a third capacitor, a ninth resistor, a fourth transistor, and a tenth resistor.
[0025] The first pin of the second optocoupler is connected to the second power supply voltage via the seventh resistor. The second pin of the second optocoupler serves as the input terminal of the second isolation circuit and is connected to the output terminal of the RS485 circuit and the output terminal of the MBUS circuit. The third pin of the second optocoupler is connected to the first terminal of the eighth resistor, the first terminal of the third capacitor, and the first terminal of the ninth resistor. The fourth pin of the second optocoupler is connected to the first power supply voltage.
[0026] The second terminal of the eighth resistor is connected to the second terminal of the third capacitor and the base of the fourth transistor;
[0027] The second terminal of the ninth resistor and the emitter of the fourth transistor are both grounded;
[0028] The collector of the fourth transistor and the first terminal of the tenth resistor are connected to the input terminal of the microcontroller unit as the output terminal of the second isolation circuit.
[0029] The second terminal of the tenth resistor is connected to the first power supply voltage.
[0030] Optionally, the RS485 circuit is an RS485 chip. The non-inverting input / output terminal of the RS485 chip is connected to the positive terminal of the 485 terminal, and the inverting input / output terminal of the RS485 chip is connected to the negative terminal of the 485 terminal. The data transmitting terminal of the RS485 chip is connected to the input terminal of the second isolation circuit as the output terminal of the RS485 circuit, and the data receiving terminal of the RS485 chip is connected to the output terminal of the first isolation circuit as the input terminal of the RS485 circuit.
[0031] Optionally, the RS485 circuit also includes an eleventh resistor, a first transient voltage suppressor, a twelfth resistor, a thirteenth resistor, and a fourth capacitor;
[0032] The first end of the eleventh resistor is connected to the positive terminal of the 485 terminal, and the second end of the eleventh resistor is connected to the first end of the first transient voltage suppressor, the first end of the twelfth resistor, and the non-inverting input / output terminal of the RS485 chip.
[0033] The second terminal of the first transient voltage suppressor is connected to the negative terminal of the 485 terminal, the first terminal of the thirteenth resistor, and the inverting input / output terminal of the RS485 chip;
[0034] The second terminal of the twelfth resistor, the power supply terminal of the RS485 chip, and the first terminal of the fourth capacitor are all connected to the second power supply voltage.
[0035] The second terminal of the fourth capacitor is grounded;
[0036] The second terminal of the thirteenth resistor is grounded to the ground terminal of the RS485 chip.
[0037] Optionally, the MBUS circuit includes a fourteenth resistor, a second transient voltage suppressor, a fifteenth resistor, a first diode, a sixteenth resistor, a fifth capacitor, a fifth transistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a second diode, a sixth transistor, a twenty-first resistor, a twenty-second resistor, a first Zener diode, and a second Zener diode.
[0038] The first end of the fourteenth resistor is connected to the positive terminal of the MBUS terminal, and the second end of the fourteenth resistor is connected to the first end of the second transient voltage suppressor, the positive terminal of the first diode, the first end of the fifteenth resistor, and the first end of the sixteenth resistor.
[0039] The second terminal of the second transient voltage suppressor and the negative terminal of the MBUS terminal are both grounded;
[0040] The negative terminal of the first diode is connected to the first terminal of the seventeenth resistor;
[0041] The second terminal of the seventeenth resistor is connected to the first terminal of the fifth capacitor and the emitter of the fifth transistor;
[0042] The second terminal of the fifth capacitor and the first terminal of the eighteenth resistor are both grounded;
[0043] The second terminal of the fifteenth resistor is connected to the base of the fifth transistor;
[0044] The emitter of the five-stage transistor is connected to the first terminal of the nineteenth resistor;
[0045] The second terminal of the nineteenth resistor is connected to the second terminal of the eighteenth resistor and the base of the sixth transistor;
[0046] The collector of the sixth transistor is connected to the output terminal of the MBUS circuit, the input terminal of the second isolation circuit, and the output terminal of the RS485 circuit. The emitter of the sixth transistor is grounded.
[0047] The second terminal of the fifteenth resistor is connected to the first terminal of the twentieth resistor;
[0048] The second terminal of the twentieth resistor is connected to the positive terminal of the second diode and the emitter of the seventh transistor;
[0049] The cathode of the second diode is connected to the base of the seventh transistor, the first terminal of the twenty-first resistor, and the anode of the first Zener diode.
[0050] The collector of the seventh transistor is connected to the first terminal of the twenty-second resistor;
[0051] The cathode of the first Zener diode and the anode of the second Zener diode are connected as the input terminal of the MBUS circuit and the second terminal of the conversion circuit.
[0052] The second terminal of the twenty-first resistor and the second terminal of the twenty-second resistor are both connected to the third power supply voltage;
[0053] The cathode of the second Zener diode is grounded.
[0054] This utility model also provides an energy meter, including a communication circuit with a multiplexed port as described above.
[0055] This application provides a communication circuit and an energy meter with a multiplexed port. The communication circuit with the multiplexed port includes: a conversion circuit, a first isolation circuit, and a second isolation circuit. Both the first and second isolation circuits include an optocoupler. The input terminal of the first isolation circuit is connected to the output terminal of a microcontroller unit, and the output terminal of the first isolation circuit is connected to the input terminal of an RS485 circuit and the first terminal of the conversion circuit. The input terminal of the second isolation circuit is connected to the output terminal of the RS485 circuit, and the output terminal of the second isolation circuit is connected to the input terminal of the microcontroller unit. When the microcontroller unit is in RS485 communication mode, communication between the microcontroller unit and the RS485 circuit is achieved through the data transmission channel formed by the first isolation circuit and the data reception channel formed by the second isolation circuit. The second terminal of the conversion circuit is connected to the input terminal of an MBUS circuit, and the input terminal of the second isolation circuit is connected to the output terminal of the MBUS circuit. When the microcontroller unit is in MBUS communication mode, communication between the microcontroller unit and the MBUS circuit is achieved through the data transmission channel formed by the first isolation circuit and the conversion circuit and the data reception channel formed by the second isolation circuit. As can be seen, this application utilizes two data transmission channels constructed by the first isolation circuit, the second isolation circuit, and the conversion circuit to realize two communication modes, reducing the design space of the communication circuit of the multiplexed port. Furthermore, the design of the first isolation circuit and the second isolation circuit each employs an optocoupler, thereby reducing the overall number of optocouplers used, thus reducing design costs and improving the economy of related electronic equipment. Attached Figure Description
[0056] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0057] Figure 1 This is a schematic diagram of the structure of an existing communication circuit with a multiplexed port.
[0058] Figure 2 A schematic diagram of the structure of a communication circuit with a multiplexed port provided by this utility model;
[0059] Figure 3 A schematic diagram of the structure of a specific multiplexed port communication circuit provided by this utility model;
[0060] The attached diagram is labeled as follows: 1 is the conversion circuit, 2 is the first isolation circuit, 3 is the second isolation circuit, 4 is the RS485 circuit, 5 is the microcontroller unit, and 6 is the MBUS circuit. Detailed Implementation
[0061] The core of this utility model is to provide a communication circuit and energy meter with a multiplexed port, which can realize two communication modes by using two data transmission channels constructed by a first isolation circuit, a second isolation circuit and a conversion circuit. This reduces the design space of the communication circuit with the multiplexed port. Furthermore, the design of the first isolation circuit and the second isolation circuit each adopts an optocoupler, which reduces the overall number of optocouplers used, thereby reducing the design cost and improving the economy of related electronic equipment.
[0062] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.
[0063] For details, please see Figure 2 As shown, Figure 2 This is a schematic diagram of the structure of a communication circuit with a multiplexed port provided by this utility model.
[0064] The communication circuit of this multiplexed port includes: a conversion circuit 1, a first isolation circuit 2, and a second isolation circuit 3, wherein both the first isolation circuit 2 and the second isolation circuit 3 include an optocoupler. In addition, Figure 2 The circuit shown also includes: RS485 circuit 4, microcontroller unit 5, and MBUS circuit 6. The connection relationship of the communication circuit of this multiplexed port is as follows: the input terminal of the first isolation circuit 2 is connected to the output terminal of the microcontroller unit 5; the output terminal of the first isolation circuit 2 is connected to the input terminal of the RS485 circuit 4 and the first terminal of the conversion circuit 1; the input terminal of the second isolation circuit 3 is connected to the output terminal of the RS485 circuit 4; the output terminal of the second isolation circuit 3 is connected to the input terminal of the microcontroller unit 5; the second terminal of the conversion circuit 1 is connected to the input terminal of the MBUS circuit 6; and the input terminal of the second isolation circuit 3 is connected to the output terminal of the MBUS circuit 6.
[0065] Specifically, when the electricity meter is powered on and the microcontroller 5 has no data to send, the output of the microcontroller 5 is at a high level, the optocoupler in the first isolation circuit 2 is turned on, the low level is electrically isolated by the optocoupler in the first isolation circuit 2, and then the high level is output through the first isolation circuit 2. At the same time, the first terminal of the conversion circuit 1 is at a low level and the second terminal of the conversion circuit 1 is at a high level. At this time, the microcontroller 5 has no data to send to the RS485 circuit 4 or the MBUS circuit 6.
[0066] In a specific embodiment, the communication circuit of the multiplexed port described above can implement two different communication methods. For the first method: the RS485 fixture and the RS485 chip constitute the RS485 circuit 4. When the microcontroller 5 is in RS485 communication mode, the RS485 signal sent by the RS485 fixture will be sent to the RS485 chip through the RS485 terminal. When the RS485 chip sends data "0", the second pin of the optocoupler in the second isolation circuit 3 is at a low level, and the optocoupler in the second isolation circuit 3 is turned on. The low level is electrically isolated by the optocoupler in the second isolation circuit 3, and a primary low level is output from the third pin of the optocoupler in the second isolation circuit 3. The primary low level is then... The signal is converted to a secondary low level by the second isolation circuit 3, and the input terminal of the microcontroller 5 receives the secondary low level. When the output terminal of the microcontroller 5 sends a low-level data "0", the second pin of the optocoupler in the first isolation circuit 2 is at a low level, and the optocoupler in the first isolation circuit 2 is turned on. The low level is electrically isolated by the optocoupler in the first isolation circuit 2, and the primary low level is output from the third pin of the optocoupler in the first isolation circuit 2. The primary low level is converted to a secondary low level and a high level by the first isolation circuit 2, and the RS485 circuit 4 receives the secondary low level. The RS485 signal replied by the microcontroller 5 is correctly recognized by the RS485 circuit 4, realizing the communication between the microcontroller 5 and the RS485 circuit 4.
[0067] For the second scenario: When the microcontroller 5 is in MBUS communication mode, the MBUS signal sent by the MBUS fixture will be converted into a valid high / low level through the MBUS terminal and the metering device. When the output of the MBUS circuit 6 outputs a low level, the second pin of the optocoupler in the second isolation circuit 3 is at a low level, and the optocoupler in the second isolation circuit 3 is turned on. The low level is electrically isolated by the optocoupler in the second isolation circuit 3, and a primary low level is output from the third pin of the optocoupler in the second isolation circuit 3. The primary low level is converted into a secondary low level through the second isolation circuit 3, and the input of the microcontroller 5 receives the secondary low level. When the microcontroller 5... When the output terminal sends a low-level data "0", the second pin of the optocoupler in the first isolation circuit 2 is at a low level, the optocoupler in the first isolation circuit 2 is turned on, and the low level is electrically isolated by the optocoupler in the first isolation circuit 2. The primary low level is output from the third pin of the optocoupler in the first isolation circuit 2. The primary low level is converted into a secondary low level and a high level by the first isolation circuit 2. The first terminal of the conversion circuit 1 receives the high level, and the conversion circuit 1 converts the high level to a low level and outputs it to the input terminal of the MBUS circuit 6. The MBUS signal replied by the microcontroller unit 5 is correctly recognized by the MBUS circuit 6, realizing the communication between the microcontroller unit 5 and the MBUS circuit 6.
[0068] It should be noted that the input and output terminals of the microcontroller unit 5 are a set of UART ports. Communication between the microcontroller unit 5 and the RS485 circuit 4 is equivalent to communication between the microcontroller unit 5 and the RS485 communication fixture; communication between the microcontroller unit 5 and the MBUS circuit 6 is equivalent to communication between the microcontroller unit 5 and the MBUS communication fixture. Because the communication protocols of RS485 and MBUS are different, even if the MBUS communication fixture receives the RS485 signal sent by the microcontroller unit 5 to the RS485 circuit 4, the MBUS communication fixture cannot parse it correctly and will not send an incorrect signal back to the microcontroller unit 5, thus not interfering with the RS485 communication of the microcontroller unit 5. Similarly, the RS485 communication fixture cannot parse the MBUS signal sent by the microcontroller unit 5 to the MBUS circuit 6, thus not interfering with the MBUS communication of the microcontroller unit 5.
[0069] As can be seen, this application utilizes two data transmission channels constructed by the first isolation circuit 2, the second isolation circuit 3, and the conversion circuit 1 to realize two communication modes, reducing the design space of the communication circuit of the multiplexed port. Furthermore, the design of the first isolation circuit 2 and the second isolation circuit 3 each employs an optocoupler, thereby reducing the overall number of optocouplers used, thus reducing design costs and improving the economy of related electronic equipment.
[0070] Based on the above embodiments:
[0071] Please refer to Figure 3 As shown, Figure 3 This is a schematic diagram of the structure of a specific communication circuit with a multiplexed port provided by this utility model.
[0072] As an optional embodiment, the conversion circuit 1 includes a first resistor R1 and a first transistor Q1; the first end of the first resistor R1 is connected to the output terminal of the first isolation circuit 2 and the input terminal of the RS485 circuit 4 as the first terminal of the conversion circuit 1, and the second end of the first resistor R1 is connected to the base of the first transistor Q1; the emitter of the first transistor Q1 is grounded, and the collector of the first transistor Q1 is connected to the input terminal of the MBUS circuit 6 as the second terminal of the conversion circuit 1.
[0073] Specifically, when the microcontroller 5 is in MBUS communication mode, if the output of the first isolation circuit 2 is high, the high level is output to the base of the first transistor Q1 through the first resistor R1, and the first transistor Q1 is turned on. Since the emitter of the first transistor Q1 is grounded, the collector of the first transistor Q1 changes from high level to low level, and the current of the MBUS circuit 6 fluctuates, thus sending an MBUS signal. The MBUS signal replied by the microcontroller 5 is correctly recognized by the MBUS circuit 6, realizing communication between the microcontroller 5 and the MBUS circuit 6.
[0074] It should be noted that the embodiments provided in this application are only one possible implementation method, but are not limited to this only implementation method. Users can set their own implementation methods according to their needs.
[0075] As can be seen, this embodiment utilizes two data transmission channels constructed by the first isolation circuit 2, the second isolation circuit 3, and the first resistor R1 to realize two communication methods, thereby reducing the design space of the communication circuit of the multiplexed port.
[0076] like Figure 3 As shown, the first isolation circuit 2 includes a first optocoupler isolation acceleration circuit and an inverting control circuit. The first optocoupler isolation acceleration circuit is equipped with an optocoupler. The input terminal of the first optocoupler isolation acceleration circuit is connected to the output terminal M_TXD of the microcontroller unit 5 as the input terminal of the first isolation circuit 2. The output terminal of the first optocoupler isolation acceleration circuit and the output terminal of the inverting control circuit are jointly used as the output terminal of the first isolation circuit 2. The output terminal of the first optocoupler isolation acceleration circuit is connected to the input terminal of the inverting control circuit and the input terminal of the RS485 circuit 4. The output terminal of the inverting control circuit is connected to the enable terminal of the RS485 circuit 4 and the first terminal of the conversion circuit 1.
[0077] Specifically, when the energy meter is powered on and the microcontroller 5 has no data to send, the output terminal M_TXD of the microcontroller 5 is at a high level, the optocoupler in the first isolation circuit 2 is turned on, the low level is electrically isolated by the optocoupler in the first isolation circuit 2, and the primary high level is output from the third pin of the optocoupler in the first isolation circuit 2. The primary high level is converted into the secondary high level by the first optocoupler isolation acceleration circuit, and the inverting control circuit converts the secondary high level into a low level and outputs it to the RS485 circuit 4 and the conversion circuit 1. The second terminal of the conversion circuit 1 outputs a high level, and the microcontroller 5 has no data to send to the RS485 circuit 4 or the MBUS circuit 6.
[0078] In a specific embodiment, the communication circuit of the multiplexed port described above can implement two different communication methods. For the first method: when the microcontroller 5 is in RS485 communication mode, the RS485 signal sent by the RS485 tool will be transmitted to the RS485 circuit 4 through the RS485 terminal. When the RS485 circuit 4 sends data "0", the second pin of the optocoupler in the second isolation circuit 3 is at a low level, and the optocoupler in the second isolation circuit 3 is turned on. The low level is electrically isolated by the optocoupler in the second isolation circuit 3, and a primary low level is output from the third pin of the optocoupler in the second isolation circuit 3. The primary low level is converted into a secondary low level by the second isolation circuit 3, and the input terminal M_RXD of the microcontroller 5 receives the secondary low level. Low level; when the output terminal M_TXD of the microcontroller unit 5 sends a low-level data "0", the second pin of the optocoupler in the first isolation circuit 2 is at a low level, the optocoupler in the first isolation circuit 2 is turned on, the low level is electrically isolated by the optocoupler in the first isolation circuit 2, and the primary low level is output from the third pin of the optocoupler in the first isolation circuit 2. The primary low level is converted into a secondary low level by the first optocoupler isolation acceleration circuit. The RS485 circuit 4 receives the secondary low level, and at the same time, the inverting control circuit converts the secondary low level into a high level and outputs it to the RS485 circuit 4. The 485 signal replied by the microcontroller unit 5 is correctly recognized by the RS485 circuit 4, realizing the communication between the microcontroller unit 5 and the RS485 circuit 4.
[0079] For the second scenario: When the microcontroller 5 is in MBUS communication mode, the MBUS signal sent by the MBUS fixture will be converted into a valid high / low level through the MBUS terminal and the metering device. When the output of the MBUS circuit 6 is low, the second pin of the optocoupler in the second isolation circuit 3 is low, and the optocoupler in the second isolation circuit 3 is turned on. The low level is electrically isolated by the optocoupler in the second isolation circuit 3, and a primary low level is output from the third pin of the optocoupler in the second isolation circuit 3. The primary low level is converted into a secondary low level through the second isolation circuit 3, and the input terminal M_RXD of the microcontroller 5 receives the secondary low level. When the microcontroller... When the output terminal M_TXD of unit 5 sends a low-level data "0", the second pin of the optocoupler in the first isolation circuit 2 is at a low level, the optocoupler in the first isolation circuit 2 is turned on, the low level is electrically isolated by the optocoupler in the first isolation circuit 2, and the primary low level is output from the third pin of the optocoupler in the first isolation circuit 2. The primary low level is converted into a secondary low level by the first optocoupler isolation acceleration circuit. The inverting control circuit converts the secondary low level into a high level and outputs it to the first terminal of the conversion circuit 1. The conversion circuit 1 outputs a low level, and the MBUS signal replied by the microcontroller unit 5 is correctly recognized by the MBUS circuit 6, realizing the communication between the microcontroller unit 5 and the MBUS circuit 6.
[0080] As can be seen, the high / low level output of the microcontroller 5 is electrically isolated by the optocoupler of the first optocoupler isolation acceleration circuit, which can reduce noise interference and improve the safety and reliability of the communication circuit of the multiplexed port. The inverting control circuit converts the low / high level output of the first optocoupler isolation acceleration circuit to a high / low level, which can effectively control the data receiving channel to be on / off.
[0081] like Figure 3As shown, the optocoupler in the first optocoupler acceleration circuit is the first optocoupler UR1. The first optocoupler acceleration circuit also includes: a second resistor R2, a third resistor R3, a first capacitor C1, a fourth resistor R4, and a second transistor Q2. The first pin of the first optocoupler UR1 is connected to the first power supply voltage VDD1 via the second resistor R2. The second pin of the first optocoupler UR1 serves as the input terminal of the first optocoupler isolation acceleration circuit and is connected to the output terminal M_TXD of the microcontroller unit 5. The third pin of the first optocoupler UR1 is connected to the first terminal of the third resistor R3, the first terminal of the first capacitor C1, and the first terminal of the fourth resistor R4. The fourth pin of the first optocoupler UR1 is connected to the second power supply voltage VDD2. The second terminal of the third resistor R3 is connected to the second terminal of the first capacitor C1 and the base of the second transistor Q2. The second terminal of the fourth resistor R4 and the emitter of the second transistor Q2 are both grounded. The collector of the second transistor Q2 serves as the output terminal of the first optocoupler isolation acceleration circuit and is connected to the input terminal of the inverting control circuit and the input terminal of the RS485 circuit 4.
[0082] Specifically, the first optocoupler UR1 converts the signal output from the microcontroller unit 5 from an electrical signal to an optical signal, and then converts the optical signal back to an electrical signal, completing the electro-optical-electrical conversion and avoiding interference and risks associated with direct electrical connection. The signal then passes through an optocoupler acceleration circuit composed of a second resistor R2, a third resistor R3, a first capacitor C1, a fourth resistor R4, and a second transistor Q2, improving the signal transmission speed. The first power supply voltage VDD1 can be +3.3V.
[0083] like Figure 3 As shown, the inverting control circuit includes a fifth resistor R5, a third transistor Q3, a second capacitor C2, and a sixth resistor R6. The first end of the fifth resistor R5 serves as the input terminal of the inverting control circuit and is connected to the output terminal of the first optocoupler isolation acceleration circuit and the input terminal of the RS485 circuit 4. The second end of the fifth resistor R5 is connected to the base of the third transistor Q3. The emitter of the third transistor Q3 is connected to the second power supply voltage VDD2. The collector of the third transistor Q3, the first end of the second capacitor C2, and the first end of the sixth resistor R6 together serve as the output terminal of the inverting control circuit and are connected to the enable terminal of the RS485 circuit 4 and the first terminal of the conversion circuit 1. The second ends of the second capacitor C2 and the second ends of the sixth resistor R6 are both grounded.
[0084] Specifically, when the input of the inverting control circuit is low, the low level is output to the base of the third transistor Q3 through the fifth resistor R5. Since the emitter of the third transistor Q3 is connected to the second power supply voltage VDD2, the third transistor Q3 is turned on, and the collector of the third transistor Q3 outputs a high level, i.e., the inverting control circuit outputs a high level. When the input of the inverting control circuit is high, the high level is output to the base of the third transistor Q3 through the fifth resistor R5. Since the emitter of the third transistor Q3 is connected to the second power supply voltage VDD2, the third transistor Q3 is turned off. Since the second terminal of the sixth resistor R6 is grounded, the output of the inverting control circuit is pulled down to a low level through the sixth resistor R6. The third power supply voltage VDD3 can be +5V.
[0085] like Figure 3 As shown, the optocoupler in the second isolation circuit 3 is the second optocoupler UR2. The second isolation circuit 3 also includes a seventh resistor R7, an eighth resistor R8, a third capacitor C3, a ninth resistor R9, a fourth transistor Q4, and a tenth resistor R10. The first pin of the second optocoupler UR2 is connected to the second power supply voltage VDD2 via the seventh resistor R7. The second pin of the second optocoupler UR2 serves as the input terminal of the second isolation circuit 3 and is connected to the output terminal of the RS485 circuit 4 and the output terminal of the MBUS circuit 6. The third pin of the second optocoupler UR2 is connected to the eighth resistor R8. The first terminal of the second optocoupler UR2 is connected to the first power supply voltage VDD1; the second terminal of the eighth resistor R8 is connected to the second terminal of the third capacitor C3 and the base of the fourth transistor Q4; the second terminal of the ninth resistor R9 and the emitter of the fourth transistor Q4 are both grounded; the collector of the fourth transistor Q4 and the first terminal of the tenth resistor R10 are connected to the output terminal of the second isolation circuit 3 and the input terminal M_RXD of the microcontroller unit 5; the second terminal of the tenth resistor R10 is connected to the first power supply voltage VDD1.
[0086] For an introduction to the second isolation circuit 3 provided in this embodiment, please refer to the embodiment of the first optocoupler acceleration circuit described above. This utility model will not be described again here.
[0087] like Figure 3 As shown, RS485 circuit 4 is RS485 chip UR3. The non-inverting input / output terminal A of RS485 chip UR3 is connected to the positive terminal of 485 terminal, and the inverting input / output terminal B of RS485 chip UR3 is connected to the negative terminal of 485 terminal. The data transmitting terminal RO of RS485 chip UR3 is connected to the input terminal of the second isolation circuit 3 as the output terminal of RS485 circuit 4, and the data receiving terminal of RS485 chip UR3 is connected to the output terminal of the first isolation circuit 2 as the input terminal of RS485 circuit 4.
[0088] Specifically, the power supply terminal VDD of RS485 chip UR3 is connected to the second power supply voltage VDD2, and the ground terminal GND of RS485 chip UR3 is grounded. When the microcontroller unit 5 is in RS485 communication mode, if the positive terminal of the 485 terminal is at a high level and the negative terminal of the 485 terminal is at a low level, then the differential signal of the non-inverting input / output terminal A of RS485 chip UR3 minus the inverting input / output terminal B is at a high level, and at this time, the data transmission terminal RO of RS485 chip UR3 outputs a high level; if the positive terminal of RS485 is at a low level and the negative terminal of the 485 terminal is at a low level, then the differential signal of the non-inverting input / output terminal A of RS485 chip UR3 minus the inverting input / output terminal B is at a low level, and at this time, the data output terminal of RS485 chip UR3 outputs a low level.
[0089] As can be seen, the RS485 chip UR3 uses differential signal transmission. Using the RS485 chip UR3 as RS485 circuit 4 can enhance the electromagnetic interference resistance of the communication circuit of the multiplexed port.
[0090] To improve the security of the communication circuit of the multiplexed port, this embodiment sets an eleventh resistor R11 and a first transient voltage suppressor DH1 between the 485 terminal and the RS485 chip UR3. The first end of the eleventh resistor R11 is connected to the positive terminal of the 485 terminal, the second end of the eleventh resistor R11 is connected to the first end of the first transient voltage suppressor DH1, the first end of the twelfth resistor R12 and the non-inverting input / output terminal A of the RS485 chip UR3, the second end of the first transient voltage suppressor DH1 is connected to the negative terminal of the 485 terminal, the first end of the thirteenth resistor R13 and the inverting input / output terminal B of the RS485 chip UR3. If the current of the 485 terminal is too large, the eleventh resistor R11 and the first transient voltage suppressor DH1 will activate instantaneously to prevent high voltage from damaging the RS485 chip UR3.
[0091] Furthermore, this embodiment also includes a twelfth resistor R12 and a thirteenth resistor R13. The second terminal of the twelfth resistor R12 is connected to the second power supply voltage VDD2, and the second terminal of the thirteenth resistor R13 is grounded to the ground terminal of the RS485 chip UR3. The twelfth resistor R12 is used to pull up the non-inverting input / output terminal A of the RS485 chip UR3 to the second power supply voltage VDD2, and the thirteenth resistor R13 is used to pull down the inverting input / output terminal B of the RS485 chip UR3 to ground, so as to enhance the differential signal of the non-inverting input / output terminal A minus the inverting input / output terminal B of the RS485 chip UR3, thereby playing an anti-interference role.
[0092] It can be seen that when the current at the 485 terminal is too large, the eleventh resistor R11 and the first transient voltage suppressor DH1 take effect instantly to prevent the high voltage from damaging the RS485 chip UR3; the twelfth resistor R12 and the thirteenth resistor R13 can enhance the differential signal of the non-inverting input / output terminal A minus the inverting input / output terminal B of the RS485 chip UR3, thus playing an anti-interference role.
[0093] like Figure 3 As shown, the MBUS circuit 6 includes a fourteenth resistor R14, a second transient voltage suppressor DH2, a fifteenth resistor R15, a first diode D1, a sixteenth resistor R16, a fifth capacitor C5, a fifth transistor Q5, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, a twentieth resistor R20, a second diode D2, a sixth transistor Q6, a twenty-first resistor R21, a twenty-second resistor R22, a first Zener diode DW1, and a second Zener diode DW2; the first terminal of the fourteenth resistor R14 is connected to the positive terminal of the MBUS terminal, and the fourteenth resistor... The second terminal of resistor R14 is connected to the first terminal of the second transient voltage suppressor DH2, the anode of the first diode D1, the first terminal of the fifteenth resistor R15, and the first terminal of the sixteenth resistor R16; the second terminal of the second transient voltage suppressor DH2 and the cathode of the MBUS terminal are both grounded; the cathode of the first diode D1 is connected to the first terminal of the seventeenth resistor R17; the second terminal of the seventeenth resistor R17 is connected to the first terminal of the fifth capacitor C5 and the emitter of the fifth transistor Q5; the second terminal of the fifth capacitor C5 and the first terminal of the eighteenth resistor R18 are both grounded; the fifteenth resistor R15... The second terminal is connected to the base of the fifth transistor Q5; the emitter of the fifth transistor is connected to the first terminal of the nineteenth resistor R19; the second terminal of the nineteenth resistor R19 is connected to the second terminal of the eighteenth resistor R18 and the base of the sixth transistor Q6; the collector of the sixth transistor Q6 serves as the output terminal of MBUS circuit 6 and is connected to the input terminal of the second isolation circuit 3 and the output terminal of RS485 circuit 4; the emitter of the sixth transistor Q6 is grounded; the second terminal of the fifteenth resistor R15 is connected to the first terminal of the twentieth resistor R20; the second terminal of the twentieth resistor R20 is connected to the second diode D2. The positive terminal is connected to the emitter of the seventh transistor Q7; the cathode of the second diode D2 is connected to the base of the seventh transistor Q7, the first terminal of the twenty-first resistor R21, and the positive terminal of the first Zener diode; the collector of the seventh transistor Q7 is connected to the first terminal of the twenty-second resistor R22; the cathode of the first Zener diode and the anode of the second Zener diode are connected as the input terminal of MBUS circuit 6 and the second terminal of conversion circuit 1; the second terminals of the twenty-first resistor R21 and the second terminals of the twenty-second resistor R22 are both connected to the third power supply voltage VDD3; the cathode of the second Zener diode is grounded.
[0094] Specifically, when the microcontroller 5 is in MBUS communication mode, the MBUS signal sent by the MBUS fixture will be converted into a valid high / low level through the MBUS terminal via the fifteenth resistor R15, the first diode D1, the sixteenth resistor R16, the fifth capacitor C5, the fifth transistor Q5, the seventeenth resistor R17, the eighteenth resistor R18, the nineteenth resistor R19, the twentieth resistor R20, the second diode D2, the sixth transistor Q6, the twenty-first resistor R21, and the twenty-second resistor R22. The output of the MBUS circuit 6 will output the high / low level to the input of the second isolation circuit 3. When the output terminal M_TXD of the microcontroller 5 sends a low-level data "0", the second pin of the optocoupler in the first isolation circuit 2 will be low. When the optocoupler in the first isolation circuit 2 is turned on, the low level is electrically isolated by the optocoupler in the first isolation circuit 2, and the primary low level is output from the third pin of the optocoupler in the first isolation circuit 2. The primary low level is converted into the secondary low level by the optocoupler acceleration circuit. The inverting control circuit converts the secondary low level into the high level and outputs it to the first terminal of the conversion circuit 1. The conversion circuit 1 outputs a low level. The current of the circuit composed of the fourteenth resistor R14, the sixteenth resistor R16, the twentieth resistor R20, the second diode D2, the sixth transistor Q6, and the twenty-second resistor R22 fluctuates. The MBUS signal replied by the microcontroller 5 is correctly recognized by the MBUS circuit 6, realizing the communication between the microcontroller 5 and the MBUS circuit 6.
[0095] As can be seen, in this embodiment, the MBUS signal is converted into a valid high / low level and sent to the second isolation circuit 3 through the fifteenth resistor R15, the first diode D1, the sixteenth resistor R16, the fifth capacitor C5, the fifth transistor Q5, the seventeenth resistor R17, the eighteenth resistor R18, the nineteenth resistor R19, the twentieth resistor R20, the second diode D2, the sixth transistor Q6, the twenty-first resistor R21, and the twenty-second resistor R22. When there is a fluctuation in the current of the circuit composed of the fourteenth resistor R14, the sixteenth resistor R16, the twentieth resistor R20, the second diode D2, the sixth transistor Q6, and the twenty-second resistor R22, the MBUS signal replied by the microcontroller 5 is received, thereby realizing the communication between the microcontroller 5 and the MBUS circuit 6.
[0096] It should be noted that the embodiments provided in this application are only one possible implementation method, but are not limited to this only implementation method. Users can set their own implementation methods according to their needs.
[0097] Based on the above circuit structure, the function (specific implementation) of the communication circuit of the multiplexed port provided in this application is as follows:
[0098] When the energy meter is powered on and the microcontroller 5 has no data to send, the output of the microcontroller 5 is high, the first optocoupler UR1 is turned on, the low level is electrically isolated through the first optocoupler UR1, and the primary high level is output from the third pin of the first optocoupler UR1. The primary high level is converted into the secondary high level through the second resistor R2, the third resistor R3, the first capacitor C1, the fourth resistor R4 and the second transistor Q2. The RS485 chip UR3 receives the secondary high level. At the same time, the fifth resistor R5, the third transistor Q3, the second capacitor C2 and the sixth resistor R6 convert the secondary high level into a low level and output it to the enable pin of the RS485 chip UR3. The RS485 chip UR3 is not enabled. At the same time, the first end of the first resistor R1 is low, the collector of the first transistor Q1 outputs a high level, and the microcontroller 5 has no data to send to the RS485 circuit 4 or the MBUS circuit 6.
[0099] When the microcontroller 5 is in RS485 communication mode, the RS485 signal sent by the RS485 tooling will be sent to the RS485 chip UR3 through the RS485 terminal. When the RS485 chip UR3 sends data "0", the second pin of the second optocoupler UR2 is at a low level, and the second optocoupler UR2 is turned on. The low level is electrically isolated by the second optocoupler UR2, and the primary low level is output from the third pin of the second optocoupler UR2. The primary low level is converted into a secondary low level through the seventh resistor R7, the eighth resistor R8, the third capacitor C3, the ninth resistor R9, the fourth transistor Q4, and the tenth resistor R10. The input terminal M_RXD of the microcontroller 5 receives the secondary low level. When the output terminal M_TXD of the microcontroller 5 sends low-level data "0", the first optocoupler... When the second pin of coupler UR1 is low, the first optocoupler UR1 is turned on. The low level is electrically isolated by the first optocoupler UR1, and a primary low level is output from the third pin of the first optocoupler UR1. The primary low level is converted into a secondary low level through the second resistor R2, the third resistor R3, the first capacitor C1, the fourth resistor R4, and the second transistor Q2. The RS485 chip UR3 receives the secondary low level. At the same time, the fifth resistor R5, the third transistor Q3, the second capacitor C2, and the sixth resistor R6 convert the secondary low level into a high level and output it to the enable terminal of the RS485 chip UR3. The RS485 chip UR3 is triggered and enabled. The 485 signal replied by the microcontroller 5 is correctly recognized by the RS485 chip UR3, realizing the communication between the microcontroller 5 and the RS485 circuit 4.
[0100] When the microcontroller 5 is in MBUS communication mode, the MBUS signal sent by the MBUS fixture will be converted into a valid high / low level through the MBUS terminal via the fourteenth resistor R14, the second transient voltage suppressor DH2, the fifteenth resistor R15, the first diode D1, the fifth capacitor C5, the fifth transistor Q5, the seventeenth resistor R17, the eighteenth resistor R18, the nineteenth resistor R19, and the sixth transistor Q6. When the collector of the sixth transistor Q6 outputs a low level, the second pin of the second optocoupler UR2 is at a low level, and the second optocoupler UR2 is turned on. The low level is electrically isolated through the second optocoupler UR2, and a primary low level is output from the third pin of the second optocoupler UR2. The primary low level is converted into a secondary low level through the seventh resistor R7, the eighth resistor R8, the third capacitor C3, the ninth resistor R9, the fourth transistor Q4, and the tenth resistor R10. When the input terminal M_RXD of the microcontroller unit 5 receives a secondary low level, and the output terminal M_TXD of the microcontroller unit 5 sends a low-level data "0", the second pin of the first optocoupler UR1 is at a low level, the first optocoupler UR1 is turned on, the low level is electrically isolated by the first optocoupler UR1, and the primary low level is output from the third pin of the first optocoupler UR1. The primary low level is converted into a secondary low level through the second resistor R2, the third resistor R3, the first capacitor C1, the fourth resistor R4 and the second transistor Q2. The fifth resistor R5, the third transistor Q3, the second capacitor C2 and the sixth resistor R6 convert the secondary low level into a high level and output it to the first terminal of the first resistor R1. The collector of the first transistor Q1 outputs a low level. The MBUS signal replied by the microcontroller unit 5 is correctly recognized by the MBUS circuit 6, realizing the communication between the microcontroller unit 5 and the MBUS circuit 6.
[0101] This utility model also provides an energy meter, including a communication circuit with a multiplexed port as described above.
[0102] In addition to the above, in practical applications, the electricity meter also includes a power supply module, which provides a first power supply voltage VDD1, a second power supply voltage VDD2, and a third power supply voltage VDD3 to the communication circuit of the multiplexed port. For a description of the electricity meter provided in this embodiment, please refer to the above embodiment of the communication circuit of the multiplexed port; this utility model will not be described again here.
[0103] As can be seen, the energy meter of this application can realize two communication modes by using two data transmission channels constructed by the first isolation circuit 2, the second isolation circuit 3 and the conversion circuit 1, which reduces the design space of the communication circuit of the multiplexed port. Furthermore, the design of the first isolation circuit 2 and the second isolation circuit 3 each adopts an optocoupler, which reduces the overall number of optocouplers used, thereby reducing the design cost and improving the economy of related electronic equipment.
[0104] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.
[0105] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0106] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A communication circuit for multiplexing ports, characterized by The application relates to a conversion circuit, a first isolation circuit and a second isolation circuit, wherein the first isolation circuit and the second isolation circuit each comprise an optoelectronic coupler. The input end of the first isolation circuit is connected with the output end of a micro control unit, the output end of the first isolation circuit is connected with the input end of an RS485 circuit and the first end of the conversion circuit, the input end of the second isolation circuit is connected with the output end of the RS485 circuit, and the output end of the second isolation circuit is connected with the input end of the micro control unit; when the micro control unit is in an RS485 communication state, the communication between the micro control unit and the RS485 circuit is realized through a data sending channel formed by the first isolation circuit and a data receiving channel formed by the second isolation circuit. The second end of the conversion circuit is connected with the input end of an MBUS circuit, the input end of the second isolation circuit is connected with the output end of the MBUS circuit, and when the micro control unit is in an MBUS communication state, the communication between the micro control unit and the MBUS circuit is realized through a data sending channel formed by the first isolation circuit and the conversion circuit and a data receiving channel formed by the second isolation circuit. The conversion circuit comprises a first resistor and a first triode.
2. The multiplexed ported communications circuit of claim 1, wherein, The first end of the first resistor is connected with the output end of the first isolation circuit and the input end of the RS485 circuit as the first end of the conversion circuit, the second end of the first resistor is connected with the base of the first triode, the emitter of the first triode is grounded, and the collector of the first triode is connected with the input end of the MBUS circuit as the second end of the conversion circuit. The first isolation circuit comprises a first optoelectronic coupler isolation acceleration circuit and an inverting control circuit, and the first optoelectronic coupler isolation acceleration circuit is provided with the optoelectronic coupler. The input end of the first optoelectronic coupler isolation acceleration circuit is connected with the output end of the micro control unit as the input end of the first isolation circuit, and the output end of the first optoelectronic coupler isolation acceleration circuit is connected with the output end of the inverting control circuit as the output end of the first isolation circuit.
3. The multiplexed ported communications circuit of claim 1, wherein, The output end of the first optoelectronic coupler isolation acceleration circuit is connected with the input end of the inverting control circuit and the input end of the RS485 circuit. The output end of the inverting control circuit is connected with the enable end of the RS485 circuit and the first end of the conversion circuit. The optoelectronic coupler in the first optoelectronic coupler isolation acceleration circuit is a first optoelectronic coupler, and the first optoelectronic coupler isolation acceleration circuit further comprises a second resistor, a third resistor, a first capacitor, a fourth resistor and a second triode. The first pin of the first optoelectronic coupler is connected with a first power supply voltage through the second resistor, the second pin of the first optoelectronic coupler is connected with the output end of the micro control unit as the input end of the first optoelectronic coupler isolation acceleration circuit, the third pin of the first optoelectronic coupler is connected with the first end of the third resistor, the first end of the first capacitor and the first end of the fourth resistor, and the fourth pin of the first optoelectronic coupler is connected with a second power supply voltage.
4. The multiplexed ported communications circuit of claim 3, wherein, The second end of the third resistor is connected with the second end of the first capacitor and the base of the second triode; The second end of the fourth resistor and the emitter of the second triode are grounded; The collector of the second triode is connected with the input end of the inverting control circuit and the input end of the RS485 circuit as the output end of the first optocoupler isolation acceleration circuit.
5. The multiplexed port communications circuit of claim 3, wherein, The inverting control circuit comprises a fifth resistor, a third triode, a second capacitor and a sixth resistor; The first end of the fifth resistor is connected with the output end of the first optocoupler isolation acceleration circuit and the input end of the RS485 circuit as the input end of the inverting control circuit, and the second end of the fifth resistor is connected with the base of the third triode; The emitter of the third triode is connected with the second power supply voltage, and the collector of the third triode, the first end of the second capacitor and the first end of the sixth resistor are connected with the enable end of the RS485 circuit and the first end of the conversion circuit as the output end of the inverting control circuit; The second end of the second capacitor and the second end of the sixth resistor are grounded.
6. The multiplexed ported communications circuit of claim 1, wherein, The photoelectric coupler in the second isolation circuit is a second photoelectric coupler, and the second isolation circuit further comprises a seventh resistor, an eighth resistor, a third capacitor, a ninth resistor, a fourth triode and a tenth resistor; The first pin of the second photoelectric coupler is connected with the second power supply voltage through the seventh resistor, the second pin of the second photoelectric coupler is connected with the output end of the RS485 circuit and the output end of the MBUS circuit as the input end of the second isolation circuit, the third pin of the second photoelectric coupler is connected with the first end of the eighth resistor, the first end of the third capacitor and the first end of the ninth resistor, and the fourth pin of the second photoelectric coupler is connected with the first power supply voltage; The second end of the eighth resistor is connected with the second end of the third capacitor and the base of the fourth triode; The second end of the ninth resistor is connected with the emitter of the fourth triode; The collector of the fourth triode and the first end of the tenth resistor are connected with the input end of the micro control unit as the output end of the second isolation circuit; The second end of the tenth resistor is connected with the first power supply voltage.
7. The multiplexed ported communications circuit of claim 1, wherein, The RS485 circuit is an RS485 chip, the same phase input and output end of the RS485 chip is connected with the positive pole of the 485 terminal, the opposite phase input and output end of the RS485 chip is connected with the negative pole of the 485 terminal, the data sending end of the RS485 chip is connected with the input end of the second isolation circuit as the output end of the RS485 circuit, and the data receiving end of the RS485 chip is connected with the output end of the first isolation circuit as the input end of the RS485 circuit.
8. The multiplexed ported communications circuit of claim 7, wherein, The RS485 circuit further comprises an eleventh resistor, a first transient voltage suppression tube, a twelfth resistor, a thirteenth resistor and a fourth capacitor; A first end of the eleventh resistor is connected to a positive pole of the 485 terminal, and a second end of the eleventh resistor is connected to a first end of the first transient voltage suppression tube, a first end of the twelfth resistor and a non-inverting input / output terminal of the RS485 chip; A second end of the first transient voltage suppression tube is connected to a negative pole of the 485 terminal, a first end of the thirteenth resistor and an inverting input / output terminal of the RS485 chip; A second end of the twelfth resistor, a power supply terminal of the RS485 chip and a first end of the fourth capacitor are connected to a second power supply voltage; A second end of the fourth capacitor is grounded; A second end of the thirteenth resistor and a ground terminal of the RS485 chip are grounded.
9. The multiplexed ported communications circuit of claim 7, wherein, The MBUS circuit comprises a fourteenth resistor, a second transient voltage suppression tube, a fifteenth resistor, a first diode, a sixteenth resistor, a fifth capacitor, a fifth transistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a second diode, a sixth transistor, a twenty-first resistor, a twenty-second resistor, a seventh transistor, a first voltage stabilizing tube and a second voltage stabilizing tube; A first end of the fourteenth resistor is connected to a positive pole of an MBUS terminal, and a second end of the fourteenth resistor is connected to a first end of the second transient voltage suppression tube, a positive pole of the first diode, a first end of the fifteenth resistor and a first end of the sixteenth resistor; A second end of the second transient voltage suppression tube and a negative pole of the MBUS terminal are grounded; A negative pole of the first diode is connected to a first end of the seventeenth resistor; A second end of the seventeenth resistor is connected to a first end of the fifth capacitor and an emitter of the fifth transistor; A second end of the fifth capacitor and a first end of the eighteenth resistor are grounded; A second end of the fifteenth resistor is connected to a base of the fifth transistor; An emitter of the fifth transistor is connected to a first end of the nineteenth resistor; A second end of the nineteenth resistor is connected to a second end of the eighteenth resistor and a base of the sixth transistor; A collector of the sixth transistor, as an output terminal of the MBUS circuit, is connected to an input terminal of the second isolation circuit and an output terminal of the RS485 circuit, and an emitter of the sixth transistor is grounded; A second end of the fifteenth resistor is connected to a first end of the twentieth resistor; A second end of the twentieth resistor is connected to a positive pole of the second diode and an emitter of the seventh transistor; A cathode of the second diode is connected to a base of the seventh transistor, a first end of the twenty-first resistor and a positive pole of the first voltage stabilizing tube; A collector of the seventh transistor is connected to a first end of the twenty-second resistor; A cathode of the first voltage stabilizing tube and an anode of the second voltage stabilizing tube, as an input terminal of the MBUS circuit, are connected to a second end of the conversion circuit; A second end of the twenty-first resistor and a second end of the twenty-second resistor are connected to a third power supply voltage; A cathode of the second voltage stabilizing tube is grounded.
10. An electric energy meter, characterized by A communication circuit comprising the multiplexing port according to any one of claims 1 to 9.