An automatic receiving and transmitting circuit based on RS485 and power line carrier communication

Abstract

The utility model relates to a receiving and transmitting circuit technical field, especially in based on the automatic receiving and transmitting circuit of RS485 and power line carrier communication, including RS485 transceiving unit, automatic switching unit and power carrier communication transceiving unit, automatic switching unit is connected with RS485 transceiving unit and power carrier communication transceiving unit respectively, RS485 transceiving unit is connected with the RS485 bus of outside, power carrier communication transceiving unit is connected with the power carrier communication bus of outside, adopts automatic switching unit to replace the scheme that MCU relay control is used in traditional, realized direct signal interaction and working mode control between RS485 bus and power carrier communication bus, need not additionally add MCU and supporting peripheral circuit, fundamentally simplified system hardware structure, reduced hardware cost and control complexity, also shortened signal transmission path simultaneously, reduced signal delay and interference risk, improved communication efficiency and stability.

Description

Technical Field

[0001] This utility model relates to the field of transceiver circuit technology, and in particular to an automatic transceiver circuit based on RS485 and power line carrier communication. Background Technology

[0002] Power line carrier communication (PLC) is a communication method that uses a power line carrier bus as the transmission medium for data transmission. Its core principle is to modulate the data signal onto a high-frequency carrier signal and then transmit the signal through the power line carrier bus. Currently, most mainstream PLC chips on the market use TTL interfaces. When communicating with an RS485 interface (where "RS" stands for "Recommended Standard," a standard developed by the Electronic Industries Association (EIA) and commonly used for long-distance, multi-device data transmission), traditional solutions require an additional MCU (microcontroller unit) for relay control. However, the introduction of an MCU necessitates a large number of peripheral auxiliary circuits, significantly increasing the complexity of the entire system's hardware structure and consequently raising hardware costs. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide an automatic transceiver circuit based on RS485 and power line carrier communication, which can realize automatic signal transmission and reception between RS485 and power line carrier without the need for additional MCU and supporting peripheral circuits.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: An automatic transceiver circuit based on RS485 and power line carrier communication includes an RS485 transceiver unit, an automatic switching unit, and a power line carrier communication transceiver unit, wherein the automatic switching unit is electrically connected to the RS485 transceiver unit and the power line carrier communication transceiver unit respectively. The RS485 transceiver unit is electrically connected to an external RS485 bus and is used to receive signals from the RS485 bus or send signals to the RS485 bus. The power line carrier communication transceiver unit is electrically connected to an external power line carrier communication bus and is used to receive signals from the power line carrier communication bus or send signals to the power line carrier communication bus.

[0005] Furthermore, the automatic switching unit includes MOSFET Q1 and MOSFET Q2; The gate of the MOS transistor Q1 is electrically connected to the digital receiving terminal of the power line carrier communication transceiver unit, the drain of the MOS transistor Q1 is electrically connected to the mode switching terminal of the RS485 transceiver unit, and the source of the MOS transistor Q1 is grounded. The gate of the MOS transistor Q2 is electrically connected to the digital receiving terminal of the RS485 transceiver unit, the drain of the MOS transistor Q2 is electrically connected to the mode switching terminal of the power line carrier communication transceiver unit, and the source of the MOS transistor Q2 is grounded.

[0006] Furthermore, the automatic switching unit also includes resistors R46, R3, and R2; One end of resistor R46 is electrically connected to the gate of MOS transistor Q1, and the other end of resistor R46 is electrically connected to one end of resistor R3 and the digital receiving end of the power line carrier communication transceiver unit. One end of resistor R2 is electrically connected to the drain of MOS transistor Q1 and the mode switching end of RS485 transceiver unit. The other ends of resistor R2 and resistor R3 are both connected to a preset power supply.

[0007] Furthermore, the automatic switching unit also includes resistors R47, R5, and R16; One end of resistor R47 is electrically connected to the gate of MOS transistor Q2, and the other end of resistor R47 is electrically connected to one end of resistor R5 and the digital receiving end of RS485 transceiver unit. One end of resistor R16 is electrically connected to the drain of MOS transistor Q2 and the mode switching end of power line carrier communication transceiver unit. The other ends of resistor R16 and resistor R5 are both connected to a preset power supply.

[0008] Furthermore, the RS485 transceiver unit includes a transceiver U5, the transceiver U5 being model number SN75176; Both data transmission terminals of the transceiver U5 are electrically connected to an external RS485 bus, the mode switching terminal of the transceiver U5 is electrically connected to an automatic switching unit, and the digital receiving terminal of the transceiver U5 is electrically connected to an automatic switching unit.

[0009] Furthermore, the RS485 transceiver unit also includes resistors R1 and R11. One end of resistor R1 is electrically connected to one data transmission port of transceiver U5 and an external RS485 bus, respectively. The other end of resistor R1 is connected to a preset power supply. One end of resistor R11 is electrically connected to another data transmission port of transceiver U5 and an external RS485 bus, respectively. The other end of resistor R11 is grounded.

[0010] Furthermore, the power line carrier communication transceiver unit includes a transceiver U1, the transceiver U1 being a THVD8000; Both data transmission terminals of the transceiver U1 are electrically connected to an external power line carrier communication bus, the mode switching terminal of the transceiver U1 is electrically connected to an automatic switching unit, and the digital receiving terminal of the transceiver U1 is electrically connected to the automatic switching unit.

[0011] Furthermore, it also includes a power line carrier coupling unit, wherein the power line carrier communication transceiver unit is electrically connected to an external power line carrier communication bus through the power line carrier coupling unit.

[0012] Furthermore, the power line carrier coupling unit includes resistors R20, R25, R45, capacitor C3, and capacitor C5; One end of resistor R20 is electrically connected to one data transmission terminal of the power line carrier communication transceiver unit, one end of resistor R25 is electrically connected to another data transmission terminal of the power line carrier communication transceiver unit, the other end of resistor R20 is electrically connected to one end of resistor R45 and one end of capacitor C3, the other end of capacitor C3 is electrically connected to an external DC power supply and an external power line carrier communication bus, the other end of resistor R25 is electrically connected to the other end of resistor R45 and one end of capacitor C5, the other end of capacitor C5 is electrically connected to the external power line carrier communication bus and the other end of capacitor C5 is grounded.

[0013] Furthermore, the power line carrier coupling unit also includes a capacitor C28, an inductor L5, and an inductor L6; One end of capacitor C28 is electrically connected to one end of inductor L6 and an external DC power supply. The other end of capacitor C28 is electrically connected to one end of inductor L5, and both the other end of capacitor C28 and one end of inductor L5 are grounded. The other end of inductor L6 is electrically connected to the other end of capacitor C3 and an external power line carrier communication bus. The other end of inductor L5 is electrically connected to the other end of capacitor C5 and an external power line carrier communication bus.

[0014] The beneficial effects of this utility model are as follows: This solution sets up an RS485 transceiver unit, an automatic switching unit, and a power line carrier communication transceiver unit. The automatic switching unit replaces the traditional MCU relay control scheme, realizing direct signal interaction and working mode control between the RS485 bus and the power line carrier communication bus. There is no need to add an additional MCU and supporting peripheral circuits, which fundamentally simplifies the system hardware structure, reduces hardware costs and control complexity, shortens the signal transmission path, reduces signal delay and interference risks, and improves communication efficiency and stability. Attached Figure Description

[0015] Figure 1 This is a block diagram showing the module connection of the automatic transceiver circuit based on RS485 and power line carrier communication of this utility model. Figure 2 This is a circuit diagram of the RS485 transceiver unit, automatic switching unit, and power line carrier communication transceiver unit of the automatic transceiver circuit based on RS485 and power line carrier communication of this utility model. Figure 3 This is a circuit diagram of the power line carrier coupling unit of the automatic transceiver circuit based on RS485 and power line carrier communication of this utility model. Label Explanation: 1. RS485 transceiver unit; 2. Automatic switching unit; 3. Power line carrier communication transceiver unit; 4. Power line carrier coupling unit. Detailed Implementation

[0016] To explain in detail the technical content, objectives, and effects of this utility model, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0017] Please refer to Figure 1 An automatic transceiver circuit based on RS485 and power line carrier communication includes an RS485 transceiver unit 1, an automatic switching unit 2, and a power line carrier communication transceiver unit 3. The automatic switching unit 2 is electrically connected to the RS485 transceiver unit 1 and the power line carrier communication transceiver unit 3, respectively. The RS485 transceiver unit 1 is electrically connected to an external RS485 bus and is used to receive signals from the RS485 bus or send signals to the RS485 bus. The power line carrier communication transceiver unit 3 is electrically connected to an external power line carrier communication bus and is used to receive signals from the power line carrier communication bus or send signals to the power line carrier communication bus.

[0018] As can be seen from the above description, the beneficial effects of this utility model are as follows: This solution sets up an RS485 transceiver unit 1, an automatic switching unit 2, and a power line carrier communication transceiver unit 3. The automatic switching unit 2 replaces the traditional MCU relay control scheme, realizing direct signal interaction and working mode control between the RS485 bus and the power line carrier communication bus. There is no need to add an additional MCU and supporting peripheral circuits, which fundamentally simplifies the system hardware structure, reduces hardware costs and control complexity, shortens the signal transmission path, reduces signal delay and interference risks, and improves communication efficiency and stability.

[0019] For further details, please refer to Figure 2 The automatic switching unit 2 includes MOSFET Q1 and MOSFET Q2; The gate of the MOS transistor Q1 is electrically connected to the digital receiving terminal of the power line carrier communication transceiver unit 3, the drain of the MOS transistor Q1 is electrically connected to the mode switching terminal of the RS485 transceiver unit 1, and the source of the MOS transistor Q1 is grounded. The gate of the MOS transistor Q2 is electrically connected to the digital receiving terminal of the RS485 transceiver unit 1, the drain of the MOS transistor Q2 is electrically connected to the mode switching terminal of the power line carrier communication transceiver unit 3, and the source of the MOS transistor Q2 is grounded.

[0020] As described above, a MOSFET is used as the core switching element of the automatic switching unit 2. By utilizing the sensitive response characteristics of the MOSFET's gate to voltage signals, precise and rapid control of the operating modes of the RS485 transceiver unit 1 and the power line carrier communication transceiver unit 3 can be achieved. At the same time, the MOSFET has the advantages of low on-resistance, low power consumption, and fast switching speed, which can effectively reduce circuit power consumption, reduce signal switching delay, ensure the timeliness and accuracy of mode switching during communication, and avoid signal transmission interruption or bit errors.

[0021] For further details, please refer to Figure 2 The automatic switching unit 2 further includes resistors R46, R3, and R2; One end of resistor R46 is electrically connected to the gate of MOS transistor Q1, and the other end of resistor R46 is electrically connected to one end of resistor R3 and the digital receiving end of power line carrier communication transceiver unit 3, respectively. One end of resistor R2 is electrically connected to the drain of MOS transistor Q1 and the mode switching end of RS485 transceiver unit 1, respectively. The other ends of resistor R2 and resistor R3 are both connected to a preset power supply.

[0022] As described above, resistor R46, acting as a current-limiting resistor, effectively limits the current flowing into the gate of MOSFET Q1, preventing excessive current from damaging the gate and protecting the MOSFET device. Resistor R3, acting as a pull-up resistor, ensures that when there is no signal at the digital receiver of power line carrier communication transceiver unit 3, the gate of MOSFET Q1 remains at a stable high level, keeping MOSFET Q1 in the conducting state. This allows the RS485 transceiver unit to maintain its default receiving mode, preventing erroneous mode switching when there is no signal. Resistor R2, acting as a pull-up resistor, pulls the mode switching terminal of RS485 transceiver unit 1 high to the preset power supply voltage when MOSFET Q1 is turned off, ensuring that RS485 transceiver unit 1 reliably switches to the transmitting mode and guarantees the stability and reliability of signal transmission.

[0023] For further details, please refer to Figure 2 The automatic switching unit 2 also includes resistors R47, R5 and R16; One end of resistor R47 is electrically connected to the gate of MOS transistor Q2, and the other end of resistor R47 is electrically connected to one end of resistor R5 and the digital receiving end of RS485 transceiver unit 1. One end of resistor R16 is electrically connected to the drain of MOS transistor Q2 and the mode switching end of power line carrier communication transceiver unit 3. The other ends of resistor R16 and resistor R5 are both connected to a preset power supply.

[0024] As described above, resistor R47 provides current limiting protection for the gate of MOSFET Q2, preventing excessive current from damaging the gate of MOSFET Q2; resistor R5, as a pull-up resistor, ensures that when there is no signal at the digital receiver of RS485 transceiver unit 1, the gate of MOSFET Q2 remains at a stable high level, turning on MOSFET Q2 and maintaining the default receiving mode of power line carrier communication transceiver unit 3; resistor R16, as a pull-up resistor, pulls the mode switching terminal of power line carrier communication transceiver unit 3 high when MOSFET Q2 is turned off, ensuring its reliable switching to the transmitting mode, further improving the functional stability of automatic switching unit 2, and ensuring the accuracy of mode switching during bidirectional signal transmission.

[0025] For further details, please refer to Figure 2 The RS485 transceiver unit 1 includes a transceiver U5, and the transceiver U5 is model number SN75176; Both data transmission terminals of the transceiver U5 are electrically connected to an external RS485 bus, the mode switching terminal of the transceiver U5 is electrically connected to the automatic switching unit 2, and the digital receiving terminal of the transceiver U5 is electrically connected to the automatic switching unit 2.

[0026] As described above, the SN75176 transceiver boasts advantages such as strong anti-interference capability, high transmission rate, and strong driving capability, making it suitable for signal transmission needs in complex industrial environments. Its standard RS485 interface design allows direct compatibility with external RS485 buses, eliminating the need for additional signal conversion circuits and simplifying the structure of RS485 transceiver unit 1. Furthermore, the SN75176 transceiver supports mode switching, enabling flexible switching between receiving and transmitting modes via the automatic switching unit 2, meeting bidirectional communication requirements and enhancing the circuit's practicality and compatibility.

[0027] For further details, please refer to Figure 2 The RS485 transceiver unit 1 further includes resistors R1 and R11. One end of resistor R1 is electrically connected to one data transmission terminal of transceiver U5 and an external RS485 bus, respectively. The other end of resistor R1 is connected to a preset power supply. One end of resistor R11 is electrically connected to another data transmission terminal of transceiver U5 and an external RS485 bus, respectively. The other end of resistor R11 is grounded.

[0028] As described above, resistor R1 acts as a pull-up resistor for the RS485 bus, and resistor R11 acts as a pull-down resistor for the RS485 bus. Together, they can maintain the bus level stably at "1" when there is no signal transmission on the RS485 bus, avoiding level fluctuations or interference signals caused by the RS485 bus being left floating, and preventing false triggering when there is no signal. At the same time, a stable bus idle level can ensure that transceiver U5 can quickly identify valid signals in the initial stage of signal reception, improving the sensitivity and accuracy of signal reception and reducing the bit error rate.

[0029] For further details, please refer to Figure 2 The power line carrier communication transceiver unit 3 includes a transceiver U1, and the transceiver U1 is of model THVD8000; Both data transmission terminals of the transceiver U1 are electrically connected to an external power line carrier communication bus. The mode switching terminal of the transceiver U1 is electrically connected to the automatic switching unit 2, and the digital receiving terminal of the transceiver U1 is electrically connected to the automatic switching unit 2.

[0030] As described above, the THVD8000 transceiver features low power consumption, high anti-interference capability, and wide voltage adaptability, effectively adapting to the complex electromagnetic environment and voltage fluctuations of the power line carrier communication bus, ensuring stable transmission of the carrier signal. It is directly connected to the mode switching terminal and digital receiver of the automatic switching unit 2, enabling automatic switching between receiving and transmitting modes without additional control logic, thus simplifying the design of the power line carrier communication transceiver unit 3. Furthermore, the high integration of the THVD8000 transceiver reduces the need for external components, further compressing circuit size and cost.

[0031] For further details, please refer to Figure 1 It also includes a power line carrier coupling unit 4, and the power line carrier communication transceiver unit 3 is electrically connected to an external power line carrier communication bus through the power line carrier coupling unit 4.

[0032] As described above, the power line carrier coupling unit 4 acts as a bridge between the power line carrier communication transceiver unit 3 and the external power line carrier communication bus. It can effectively couple the carrier signal with the power line carrier communication bus, while isolating the DC component and interference signals in the power line carrier communication bus. It prevents high voltage DC or instantaneous pulses in the power line carrier communication bus from damaging the power line carrier communication transceiver unit 3, thus protecting the core components. At the same time, through the signal filtering and matching function of the power line carrier coupling unit 4, it improves the transmission efficiency and coverage of the carrier signal on the power line carrier communication bus, reduces signal attenuation, and ensures the stability of long-distance communication.

[0033] For further details, please refer to Figure 3The power line carrier coupling unit 4 includes resistors R20, R25, and R45, and capacitors C3 and C5. One end of resistor R20 is electrically connected to one data transmission terminal of power line carrier communication transceiver unit 3, one end of resistor R25 is electrically connected to another data transmission terminal of power line carrier communication transceiver unit 3, the other end of resistor R20 is electrically connected to one end of resistor R45 and one end of capacitor C3, the other end of capacitor C3 is electrically connected to an external DC power supply and an external power line carrier communication bus, the other end of resistor R25 is electrically connected to the other end of resistor R45 and one end of capacitor C5, the other end of capacitor C5 is electrically connected to the external power line carrier communication bus and the other end of capacitor C5 is grounded.

[0034] As described above, resistors R20 and R25, acting as current-limiting resistors, limit the current during carrier signal transmission, preventing excessive current from damaging the power line carrier coupling unit 4 or the power line carrier communication transceiver unit 3. Resistor R45, acting as a terminal matching resistor, reduces carrier signal reflection at the end of the transmission line, lowers signal interference and attenuation, and improves signal transmission quality. Capacitors C3 and C5, acting as DC blocking capacitors, effectively isolate the DC component in the power line carrier communication bus, allowing only high-frequency carrier signals to pass through, preventing DC voltage from damaging the power line carrier communication transceiver unit 3, while ensuring effective transmission of the carrier signal.

[0035] For further details, please refer to Figure 3 The power line carrier coupling unit 4 further includes a capacitor C28, an inductor L5, and an inductor L6; One end of capacitor C28 is electrically connected to one end of inductor L6 and an external DC power supply. The other end of capacitor C28 is electrically connected to one end of inductor L5, and both the other end of capacitor C28 and one end of inductor L5 are grounded. The other end of inductor L6 is electrically connected to the other end of capacitor C3 and an external power line carrier communication bus. The other end of inductor L5 is electrically connected to the other end of capacitor C5 and an external power line carrier communication bus.

[0036] As described above, capacitor C28, acting as a filter capacitor, can filter out ripple interference from the external DC power supply, providing a stable DC power supply for the power line carrier coupling unit 4 and preventing power supply interference from affecting carrier signal transmission. Inductors L5 and L6, acting as high-frequency chokes, have high impedance characteristics to high-frequency carrier signals, effectively isolating high-frequency interference signals in the power line carrier communication bus, preventing interference from entering the power line carrier communication transceiver unit 3, and preventing the carrier signal output by the power line carrier communication transceiver unit 3 from leaking into the DC power supply circuit. The combination of the two further enhances the anti-interference capability of the power line carrier coupling unit 4, ensuring the purity and transmission stability of the carrier signal.

[0037] Please refer to Figures 1 to 3 As shown, Embodiment 1 of this utility model is as follows: Please refer to Figure 1 An automatic transceiver circuit based on RS485 and power line carrier communication includes an RS485 transceiver unit 1, an automatic switching unit 2, and a power line carrier communication transceiver unit 3. The automatic switching unit 2 is electrically connected to the RS485 transceiver unit 1 and the power line carrier communication transceiver unit 3, respectively. The RS485 transceiver unit 1 is electrically connected to an external RS485 bus and is used to receive signals from the RS485 bus or send signals to the RS485 bus. The power line carrier communication transceiver unit 3 is electrically connected to an external power line carrier communication bus and is used to receive signals from the power line carrier communication bus or send signals to the power line carrier communication bus.

[0038] Please refer to Figure 2 The automatic switching unit 2 includes MOS transistors Q1 and Q2. The gate of MOS transistor Q1 is electrically connected to the digital receiving terminal of the power line carrier communication transceiver unit 3, the drain of MOS transistor Q1 is electrically connected to the mode switching terminal of the RS485 transceiver unit 1, and the source of MOS transistor Q1 is grounded. The gate of MOS transistor Q2 is electrically connected to the digital receiving terminal of the RS485 transceiver unit 1, the drain of MOS transistor Q2 is electrically connected to the mode switching terminal of the power line carrier communication transceiver unit 3, and the source of MOS transistor Q2 is grounded.

[0039] Please refer to Figure 2 The automatic switching unit 2 further includes resistors R46, R3, and R2. One end of resistor R46 is electrically connected to the gate of MOS transistor Q1, and the other end of resistor R46 is electrically connected to one end of resistor R3 and the digital receiving end of power line carrier communication transceiver unit 3. One end of resistor R2 is electrically connected to the drain of MOS transistor Q1 and the mode switching end of RS485 transceiver unit 1, and the other ends of resistors R2 and R3 are both connected to a preset power supply.

[0040] Please refer to Figure 2 The automatic switching unit 2 further includes resistors R47, R5, and R16. One end of resistor R47 is electrically connected to the gate of MOS transistor Q2, and the other end of resistor R47 is electrically connected to one end of resistor R5 and the digital receiving end of RS485 transceiver unit 1. One end of resistor R16 is electrically connected to the drain of MOS transistor Q2 and the mode switching end of power line carrier communication transceiver unit 3. The other ends of resistors R16 and R5 are both connected to a preset power supply.

[0041] The automatic switching unit 2 also includes capacitors C29 and C30. For details regarding their connections to the components, please refer to [link / reference needed]. Figure 2 .

[0042] Please refer to Figure 2 The RS485 transceiver unit 1 includes a transceiver U5, which is model SN75176. Both data transmission terminals of the transceiver U5 are electrically connected to an external RS485 bus. The mode switching terminal of the transceiver U5 is electrically connected to an automatic switching unit 2, and the digital receiving terminal of the transceiver U5 is electrically connected to the automatic switching unit 2.

[0043] Please refer to Figure 2 The RS485 transceiver unit 1 further includes resistors R1 and R11. One end of resistor R1 is electrically connected to one data transmission terminal of transceiver U5 and an external RS485 bus, respectively. The other end of resistor R1 is connected to a preset power supply. One end of resistor R11 is electrically connected to another data transmission terminal of transceiver U5 and an external RS485 bus, respectively. The other end of resistor R11 is grounded.

[0044] The RS485 transceiver unit 1 also includes resistors R7 and R8. For specific connection relationships between these components, please refer to [reference needed]. Figure 2 .

[0045] Please refer to Figure 2 The power line carrier communication transceiver unit 3 includes a transceiver U1, which is a THVD8000. Both data transmission terminals of the transceiver U1 are electrically connected to an external power line carrier communication bus. The mode switching terminal of the transceiver U1 is electrically connected to an automatic switching unit 2, and the digital receiving terminal of the transceiver U1 is electrically connected to the automatic switching unit 2.

[0046] The power line carrier communication transceiver unit 3 also includes resistors R10, R49, and R48. For specific connections between these components, please refer to [reference needed]. Figure 2 .

[0047] Please refer to Figure 1 It also includes a power line carrier coupling unit 4, and the power line carrier communication transceiver unit 3 is electrically connected to an external power line carrier communication bus through the power line carrier coupling unit 4.

[0048] Please refer to Figure 3The power line carrier coupling unit 4 includes resistors R20, R25, and R45, and capacitors C3 and C5. One end of resistor R20 is electrically connected to one data transmission terminal of the power line carrier communication transceiver unit 3, and one end of resistor R25 is electrically connected to another data transmission terminal of the power line carrier communication transceiver unit 3. The other end of resistor R20 is electrically connected to one end of resistor R45 and one end of capacitor C3. The other end of capacitor C3 is electrically connected to an external DC power supply and an external power line carrier communication bus. The other end of resistor R25 is electrically connected to the other end of resistor R45 and one end of capacitor C5. The other end of capacitor C5 is electrically connected to the external power line carrier communication bus and is grounded.

[0049] Please refer to Figure 3 The power line carrier coupling unit 4 further includes a capacitor C28, an inductor L5, and an inductor L6. One end of the capacitor C28 is electrically connected to one end of the inductor L6 and an external DC power supply. The other end of the capacitor C28 is electrically connected to one end of the inductor L5, and both the other end of the capacitor C28 and one end of the inductor L5 are grounded. The other end of the inductor L6 is electrically connected to the other end of the capacitor C3 and an external power line carrier communication bus. The other end of the inductor L5 is electrically connected to the other end of the capacitor C5 and an external power line carrier communication bus.

[0050] The automatic transceiver circuit designed in this scheme is based on the automatic switching unit 2 to automatically control the working modes of RS485 transceiver unit 1 and power line carrier communication transceiver unit 3, realizing bidirectional signal transmission between the RS485 bus and the power line carrier communication bus. Specifically, it is divided into two processes: "RS485 bus sending signals to power line carrier communication bus" and "power line carrier communication bus sending signals to RS485 bus". (a) The RS485 bus sends signals to the power line carrier communication bus: When there is signal transmission on the external RS485 bus, the transceiver U5 of RS485 transceiver unit 1 receives the signal from the RS485 bus through its data transmission terminal, converts the signal into a digital signal, and transmits it to the digital receiving terminal of transceiver U5. If the received signal is "0": the digital receiving terminal of transceiver U5 outputs a low level, which is transmitted to the gate of MOSFET Q2 through resistor R47, making the gate voltage of MOSFET Q2 lower than the turn-on voltage, and MOSFET Q2 is turned off; at this time, the drain of MOSFET Q2 is connected to the preset power supply through pull-up resistor R16, and the mode switching terminal of transceiver U1 in power line carrier communication transceiver unit 3 is pulled high, and transceiver U1 switches to transmit mode; since the digital transmitting pin of transceiver U1 is grounded, transceiver U1 outputs a "0" signal to its data transmission terminal. This signal is isolated from DC and filtered for interference by power line carrier coupling unit 4, and then coupled to the external power line carrier communication bus to complete the transmission of the "0" signal; If the received signal is "1": the digital receiving terminal of transceiver U5 outputs a high level, which is transmitted to the gate of MOSFET Q2 through resistor R47. At the same time, resistor R5 further maintains the gate of MOSFET at a high level, and MOSFET Q2 is turned on. The drain of MOSFET Q2 is pulled to ground, the mode switching terminal of transceiver U1 is at a low level, transceiver U1 switches to receive mode, and the data transmission terminal of transceiver U1 enters a high-impedance state. Because the power line carrier communication bus maintains the "1" level through the pull-up resistor, the "1" signal is transmitted to the power line carrier communication bus through power line carrier coupling unit 4, completing the transmission of the "1" signal.

[0051] (ii) The power line carrier communication bus sends signals to the RS485 bus: When an external power line carrier communication bus transmits a carrier signal, the signal is first isolated from DC and filtered out by the power line carrier coupling unit 4 before being transmitted to the data transmission end of the transceiver U1 of the power line carrier communication transceiver unit 3. The transceiver U1 receives the signal and converts it into a digital signal before transmitting it to the digital receiving end of the transceiver U1. If the received signal is "0": the digital receiving terminal of transceiver U1 outputs a low level, which is transmitted to the gate of MOSFET Q1 through resistor R46, causing the MOSFET to turn off; the drain of MOSFET Q1 is connected to the preset power supply through pull-up resistor R2, the mode switching terminal of transceiver U5 in RS485 transceiver unit 1 is pulled high, and transceiver U5 switches to transmit mode; since the digital transmitting pin of transceiver U5 is grounded, transceiver U5 outputs a "0" signal to the data transmission terminal of transceiver U5, which is directly transmitted to the external RS485 bus to complete the transmission of the "0" signal; If the received signal is "1": the digital receiving terminal of transceiver U1 outputs a high level, which is transmitted to the gate of MOSFET Q1 through resistor R46. At the same time, resistor R3 maintains the gate of MOSFET Q1 at a high level, and MOSFET Q1 is turned on. The drain of MOSFET Q1 is pulled to ground, the mode switching terminal of transceiver U5 is at a low level, transceiver U5 switches to receive mode, and the data transmission terminal of transceiver U5 enters a high-impedance state. Since the RS485 bus maintains the "1" level through pull-up resistor R1 and pull-down resistor R11, the "1" signal is directly transmitted to the external RS485 bus, completing the transmission of the "1" signal.

[0052] When there is no signal transmission, MOSFETs Q1 and Q2 in the automatic switching unit 2 remain on under the action of their respective pull-up resistors (i.e., resistors R3 and R5). Transceivers U1 and U5 are both in receive mode, and the RS485 bus and the power line carrier communication bus maintain a "1" level, ensuring that the circuit is ready to receive signals at any time, thus realizing fully automatic transceiver control without MCU participation.

[0053] In summary, this utility model provides an automatic transceiver circuit based on RS485 and power line carrier communication. By setting up an RS485 transceiver unit, an automatic switching unit, and a power line carrier communication transceiver unit, and replacing the traditional MCU relay control scheme with the automatic switching unit, it realizes direct signal interaction and working mode control between the RS485 bus and the power line carrier communication bus. It eliminates the need for additional MCU and supporting peripheral circuits, fundamentally simplifying the system hardware structure, reducing hardware costs and control complexity, while also shortening the signal transmission path, reducing signal delay and interference risks, and improving communication efficiency and stability.

[0054] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent modifications made based on the content of this utility model specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. An automatic transceiver circuit based on RS485 and power line carrier communication, characterized in that, It includes an RS485 transceiver unit, an automatic switching unit, and a power line carrier communication transceiver unit, wherein the automatic switching unit is electrically connected to the RS485 transceiver unit and the power line carrier communication transceiver unit respectively; The RS485 transceiver unit is electrically connected to an external RS485 bus and is used to receive signals from the RS485 bus or send signals to the RS485 bus. The power line carrier communication transceiver unit is electrically connected to an external power line carrier communication bus and is used to receive signals from the power line carrier communication bus or send signals to the power line carrier communication bus.

2. The automatic transceiver circuit based on RS485 and power line carrier communication according to claim 1, characterized in that, The automatic switching unit includes MOSFET Q1 and MOSFET Q2; The gate of the MOS transistor Q1 is electrically connected to the digital receiving terminal of the power line carrier communication transceiver unit, the drain of the MOS transistor Q1 is electrically connected to the mode switching terminal of the RS485 transceiver unit, and the source of the MOS transistor Q1 is grounded. The gate of the MOS transistor Q2 is electrically connected to the digital receiving terminal of the RS485 transceiver unit, the drain of the MOS transistor Q2 is electrically connected to the mode switching terminal of the power line carrier communication transceiver unit, and the source of the MOS transistor Q2 is grounded.

3. The automatic transceiver circuit based on RS485 and power line carrier communication according to claim 2, characterized in that, The automatic switching unit also includes resistors R46, R3, and R2; One end of resistor R46 is electrically connected to the gate of MOS transistor Q1, and the other end of resistor R46 is electrically connected to one end of resistor R3 and the digital receiving end of the power line carrier communication transceiver unit. One end of resistor R2 is electrically connected to the drain of MOS transistor Q1 and the mode switching end of RS485 transceiver unit. The other ends of resistor R2 and resistor R3 are both connected to a preset power supply.

4. The automatic transceiver circuit based on RS485 and power line carrier communication according to claim 2, characterized in that, The automatic switching unit also includes resistors R47, R5, and R16; One end of resistor R47 is electrically connected to the gate of MOS transistor Q2, and the other end of resistor R47 is electrically connected to one end of resistor R5 and the digital receiving end of RS485 transceiver unit. One end of resistor R16 is electrically connected to the drain of MOS transistor Q2 and the mode switching end of power line carrier communication transceiver unit. The other ends of resistor R16 and resistor R5 are both connected to a preset power supply.

5. The automatic transceiver circuit based on RS485 and power line carrier communication according to claim 1, characterized in that, The RS485 transceiver unit includes a transceiver U5, and the transceiver U5 is model number SN75176; Both data transmission terminals of the transceiver U5 are electrically connected to an external RS485 bus, the mode switching terminal of the transceiver U5 is electrically connected to an automatic switching unit, and the digital receiving terminal of the transceiver U5 is electrically connected to an automatic switching unit.

6. The automatic transceiver circuit based on RS485 and power line carrier communication according to claim 5, characterized in that, The RS485 transceiver unit also includes resistors R1 and R11. One end of resistor R1 is electrically connected to one data transmission port of transceiver U5 and an external RS485 bus, respectively. The other end of resistor R1 is connected to a preset power supply. One end of resistor R11 is electrically connected to another data transmission port of transceiver U5 and an external RS485 bus, respectively. The other end of resistor R11 is grounded.

7. The automatic transceiver circuit based on RS485 and power line carrier communication according to claim 1, characterized in that, The power line carrier communication transceiver unit includes a transceiver U1, and the transceiver U1 is of model THVD8000; Both data transmission terminals of the transceiver U1 are electrically connected to an external power line carrier communication bus, the mode switching terminal of the transceiver U1 is electrically connected to an automatic switching unit, and the digital receiving terminal of the transceiver U1 is electrically connected to the automatic switching unit.

8. The automatic transceiver circuit based on RS485 and power line carrier communication according to claim 1, characterized in that, It also includes a power line carrier coupling unit, which is electrically connected to an external power line carrier communication bus through the power line carrier coupling unit.

9. The automatic transceiver circuit based on RS485 and power line carrier communication according to claim 8, characterized in that, The power line carrier coupling unit includes resistors R20, R25, and R45, and capacitors C3 and C5. One end of resistor R20 is electrically connected to one data transmission terminal of the power line carrier communication transceiver unit, one end of resistor R25 is electrically connected to another data transmission terminal of the power line carrier communication transceiver unit, the other end of resistor R20 is electrically connected to one end of resistor R45 and one end of capacitor C3, the other end of capacitor C3 is electrically connected to an external DC power supply and an external power line carrier communication bus, the other end of resistor R25 is electrically connected to the other end of resistor R45 and one end of capacitor C5, the other end of capacitor C5 is electrically connected to the external power line carrier communication bus and the other end of capacitor C5 is grounded.

10. The automatic transceiver circuit based on RS485 and power line carrier communication according to claim 9, characterized in that, The power line carrier coupling unit also includes capacitor C28, inductor L5 and inductor L6; One end of capacitor C28 is electrically connected to one end of inductor L6 and an external DC power supply. The other end of capacitor C28 is electrically connected to one end of inductor L5, and both the other end of capacitor C28 and one end of inductor L5 are grounded. The other end of inductor L6 is electrically connected to the other end of capacitor C3 and an external power line carrier communication bus. The other end of inductor L5 is electrically connected to the other end of capacitor C5 and an external power line carrier communication bus.

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