Integrated RS485 communication and power supply system based on Ethernet shielded twisted pair cable

Abstract

This invention provides an integrated RS485 communication and power supply system based on Ethernet shielded twisted-pair cables. It includes a master control device and N slave control devices. The master control device includes a first RS485 transceiver circuit and a power supply module. Each slave control device includes a second RS485 transceiver circuit and a DC-DC converter circuit. The DC-DC converter circuit is electrically connected to the second RS485 transceiver circuit. When N=1, the master control device is connected to the slave control devices via the first Ethernet shielded twisted-pair cable. When N≥2, the master control device and one of the slave control devices are connected via the first Ethernet shielded twisted-pair cable. The N slave control devices are sequentially chained together via second Ethernet shielded twisted-pair cables. This invention solves the technical problems of existing RS485 communication systems, which use separate power and communication cables, resulting in high wiring complexity, high cable costs, high labor costs, difficulties in later maintenance, and poor anti-interference capabilities.

Description

Technical Field

[0001] This utility model relates to the field of communication technology, and in particular to an integrated RS485 communication and power supply system based on Ethernet shielded twisted pair cable. Background Technology

[0002] Traditional RS485 communication systems use separate wiring for power and communication cables, requiring at least 4 to 5 independent cables. Furthermore, each terminal needs to be crimped and wired individually during wiring, which not only increases the complexity of the wiring, cable costs, and labor costs, but also hinders later inspection and maintenance, and has poor anti-interference performance. Utility Model Content

[0003] The purpose of this application is to provide an integrated RS485 communication and power supply system based on Ethernet shielded twisted pair, which solves the technical problems in the prior art where the traditional RS485 communication system uses separate wiring for power and communication cables, resulting in high wiring complexity, high cable cost, high wiring labor cost, difficulty in later maintenance, and poor anti-interference capability.

[0004] To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0005] An integrated RS485 communication and power supply system based on Ethernet shielded twisted pair cable includes a master control device and N slave control devices, where N≥1 and N is an integer;

[0006] The main control device includes a first RS485 transceiver circuit and a power supply module;

[0007] The slave device includes a second RS485 transceiver circuit and a DC-DC converter circuit, wherein the DC-DC converter circuit is electrically connected to the second RS485 transceiver circuit.

[0008] When N=1, the master control device is connected to the slave control device through a first Ethernet shielded twisted pair cable;

[0009] When N≥2, the master control device and one of the slave control devices are connected via a first Ethernet shielded twisted pair cable, and the N slave control devices are sequentially chained together via a second Ethernet shielded twisted pair cable.

[0010] In the RS485 communication and power supply integrated system based on Ethernet shielded twisted pair described in this application embodiment, the master control device is provided with a first RJ45 network port, and the slave control device is provided with a second RJ45 network port and a third RJ45 network port;

[0011] The first RS485 transceiver circuit and the power supply module are both electrically connected to the first RJ45 network port, and the second RS485 transceiver circuit, the DC-DC conversion circuit and the third RJ45 network port are all electrically connected to the second RJ45 network port.

[0012] The master control device and the slave control device are connected through the first RJ45 network port, the first Ethernet shielded twisted pair cable and the second RJ45 network port. The two ends of the second Ethernet shielded twisted pair cable are respectively connected to the third RJ45 network port of the slave control device in the front stage and the second RJ45 network port of the slave control device in the back stage.

[0013] In the RS485 communication and power supply integrated system based on Ethernet shielded twisted pair described in this application embodiment, the DC-DC conversion circuit includes a DC-DC step-down chip, a transient voltage suppression diode, a first input filter capacitor, a second input filter capacitor, a third input filter capacitor, an enable pull-up resistor, a bootstrap capacitor, a first inductor, a first feedback resistor, a second feedback resistor, a third feedback resistor, a compensation capacitor, a first output filter capacitor, and a second output filter capacitor.

[0014] One end of the transient voltage suppressor diode is connected to the VIN pin of the DC-DC step-down chip and the second RJ45 network port, and the other end is grounded. One end of both the first and second input filter capacitors is connected to the VIN pin of the DC-DC step-down chip, and the other end of each is grounded. A pull-up resistor is connected between the VIN and EN pins of the DC-DC step-down chip. One end of the third input filter capacitor is connected to the EN pin of the DC-DC step-down chip, and the other end is grounded. The two ends of the bootstrap capacitor are connected to the BOOT and SW pins of the DC-DC step-down chip. The first end of the first inductor is connected to the DC-DC step-down chip. The SW pin of the step-down chip is connected, and the second terminal is connected to the second RS485 transceiver circuit to provide a 3.3V DC voltage. One end of the first feedback resistor is connected to the second terminal of the first inductor, and the other end is connected to the second feedback resistor. The other end of the second feedback resistor is connected to the FB pin of the DC-DC step-down chip. One end of the third feedback resistor is connected to the FB pin of the DC-DC step-down chip, and the other end is grounded. One end of the compensation capacitor is connected to the second terminal of the first inductor, and the other end is grounded. One end of each of the first output filter capacitor and the second output filter capacitor is connected to the second terminal of the first inductor, and the other end of each is grounded.

[0015] In the RS485 communication and power supply integrated system based on Ethernet shielded twisted pair described in this application embodiment, the DC-DC conversion circuit further includes a reverse protection diode. The positive terminal of the reverse protection diode is connected to the transient voltage suppression diode, and the other end is connected to the VIN pin of the DC-DC step-down chip.

[0016] In the RS485 communication and power supply integrated system based on Ethernet shielded twisted pair described in this application embodiment, the DC-DC step-down chip is SGM61410XN6G / TR.

[0017] In the RS485 communication and power supply integrated system based on Ethernet shielded twisted pair described in this application embodiment, the first RS485 transceiver circuit and the second RS485 transceiver circuit have the same structure, both including an RS485 transceiver chip, a common mode inductor, a first pull-up resistor, a second pull-up resistor, a first pull-down resistor, a second pull-down resistor, an input filter circuit, a current limiting resistor, and a third output filter capacitor.

[0018] The third and fourth terminals of the common-mode inductor are connected to pins B and A of the RS485 transceiver chip, respectively. The first pull-up resistor is connected to pin A of the RS485 transceiver chip, and the other end is connected to a 3.3V DC voltage. One end of the first pull-down resistor is connected to pin B of the RS485 transceiver chip, and the other end is grounded. One end of the second pull-up resistor is connected to pin RO of the RS485 transceiver chip, and the other end is connected to a 3.3V DC voltage. One end of the second pull-down resistor is connected to pins RE and DE of the RS485 transceiver chip, and the other end is grounded. One end of the input filter circuit is connected to pin VCC of the RS485 transceiver chip, and the other end is connected to a 3.3V DC voltage. One end of the current-limiting resistor is connected to pin RO of the RS485 transceiver chip, and the other end is connected to the third output filter capacitor. The other end of the third output filter capacitor is grounded.

[0019] The first and second ends of the common-mode inductor of the first RS485 transceiver circuit are both connected to the first RJ45 network port, and the first and second ends of the common-mode inductor of the second RS485 transceiver circuit are both connected to the second RJ45 network port.

[0020] In the RS485 communication and power supply integrated system based on Ethernet shielded twisted pair described in this application embodiment, the RS485 transceiver chip is TPT75176H-SO1R.

[0021] In the RS485 communication and power supply integrated system based on Ethernet shielded twisted pair described in the embodiments of this application, the input filtering circuit includes a second inductor, a fourth input filtering capacitor, a fifth input filtering capacitor, and a sixth input filtering capacitor;

[0022] One end of the second inductor is connected to a 3.3V DC voltage, and the other end is connected to the VCC pin of the RS485 transceiver chip. One end of each of the fourth, fifth, and sixth input filter capacitors is connected to the VCC pin of the RS485 transceiver chip, and the other end of each is grounded.

[0023] In the RS485 communication and power supply integrated system based on Ethernet shielded twisted pair described in the embodiments of this application, both the first Ethernet shielded twisted pair and the second Ethernet shielded twisted pair are shielded twisted pairs that meet at least the CAT5E specification.

[0024] Compared with the prior art, the embodiments of this application have the following beneficial effects:

[0025] As can be seen from the above technical solutions, the RS485 communication and power supply integrated system based on Ethernet shielded twisted pair provided in this application embodiment transmits RS485 communication signals and DC power simultaneously by using a first Ethernet shielded twisted pair and a second Ethernet shielded twisted pair, enhancing anti-interference capabilities. Furthermore, it eliminates the need for separate wiring of communication and power lines, simplifying wiring and reducing cable and labor costs. The system connects master and slave control devices via RJ45 ports and Ethernet shielded twisted pairs, eliminating the need for crimping and wiring, thus reducing construction difficulty and further lowering labor costs. This solves the technical problems in existing technologies where traditional RS485 communication systems use separate wiring for power and communication cables, resulting in high wiring complexity, high cable costs, high labor costs, difficulties in later maintenance, and poor anti-interference capabilities. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. The drawings are not intended to be drawn to scale, and for clarity, not every component will be labeled in each drawing. The drawings described below are merely some embodiments of this application. Those skilled in the art can obtain other drawings based on these drawings without creative effort. Wherein:

[0027] Figure 1 This is a schematic diagram of the framework of an embodiment of this application.

[0028] Figure 2 This is a circuit diagram of the first / second RS485 transceiver circuit in the embodiments of this application.

[0029] Figure 3 This is a circuit diagram of the DC-DC conversion circuit in an embodiment of this application.

[0030] Explanation of reference numerals in the attached figures:

[0031] 10-Main control device, 11-Power supply module, 12-First RS485 transceiver circuit, 13-First RJ45 network port, 20-Slave control device, 21-Second RS485 transceiver circuit, 22-DC-DC conversion circuit, 23-Second RJ45 network port, 24-Third RJ45 network port, 30-First Ethernet shielded twisted pair cable, 40-Second Ethernet shielded twisted pair cable. Detailed Implementation

[0032] Traditional RS485 communication systems typically use separate wiring for power and communication cables, requiring at least 4 to 5 independent cables. Furthermore, each terminal needs to be crimped and wired individually during wiring, which not only increases the complexity of the wiring, cable costs, and labor costs, but also hinders later inspection and maintenance, and has poor anti-interference performance.

[0033] In view of this, this application provides an integrated RS485 communication and power supply system based on Ethernet shielded twisted pair cables. The concept is to simultaneously transmit RS485 communication signals and DC power using a first Ethernet shielded twisted pair cable and a second Ethernet shielded twisted pair cable, thereby enhancing anti-interference capabilities. Furthermore, it eliminates the need for separate wiring for communication and power lines, simplifying wiring and reducing cable and labor costs. The system connects master and slave control devices via RJ45 ports and Ethernet shielded twisted pair cables, eliminating the need for crimping and wiring, thus reducing construction difficulty and further lowering labor costs. This solves the technical problems in existing RS485 communication systems where separate power and communication cables result in high wiring complexity, high cable costs, high labor costs, difficulties in later maintenance, and poor anti-interference capabilities.

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0035] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0036] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0037] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0038] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0039] This application provides an integrated RS485 communication and power supply system based on Ethernet shielded twisted-pair cable, such as... Figures 1 to 3 As shown. An integrated RS485 communication and power supply system based on Ethernet shielded twisted pair cable includes a master control device 10 and N slave control devices 20, where N≥1 and N is an integer.

[0040] Due to power limitations, the number of slave devices 20 is at most 16, i.e., 1≤N≤16. It should be further noted that, for those skilled in the art, the specific number of slave devices 20 can be reasonably set according to the specific selection of the power supply module 11 and the output power.

[0041] The master control device 10 includes a first RS485 transceiver circuit 12, a power supply module 11, and a first RJ45 network port 13. The slave control device 20 includes a second RS485 transceiver circuit 21, a DC-DC converter circuit 22, a second RJ45 network port 23, and a third RJ45 network port 24. The first RS485 transceiver circuit 12 and the power supply module 11 are both electrically connected to the first RJ45 network port 13. The power supply module 11 is electrically connected to the first RS485 transceiver circuit 12. The DC-DC converter circuit 22 is electrically connected to the second RS485 transceiver circuit 21. The second RS485 transceiver circuit 21, the DC-DC converter circuit 22, and the third RJ45 network port 24 are all electrically connected to the second RJ45 network port 24. 5. Network port 23. When N=1, the master control device 10 is connected to the slave control device 20 through the first Ethernet shielded twisted pair cable 30. When N≥2, the master control device 10 and one of the slave control devices 20 are connected through the first Ethernet shielded twisted pair cable 30. The N slave control devices 20 are sequentially chained together through the second Ethernet shielded twisted pair cable 40. Specifically, the master control device 10 and the slave control device 20 are connected through the first RJ45 network port 13, the first Ethernet shielded twisted pair cable 30 and the second RJ45 network port 23. The two ends of the second Ethernet shielded twisted pair cable 40 are respectively connected to the third RJ45 network port 24 of the slave control device 20 in the previous stage and the second RJ45 network port 23 of the slave control device 20 in the subsequent stage.

[0042] The power supply module 11 is a conventional product, and its specific structure is not the focus of this application. It only needs to provide electrical isolation and a 24V DC voltage, so it will not be elaborated upon here. For example, the Mornsun VRB2424LD-20WR3 power supply module can achieve the function of the power supply module 11. The power supply module 11 provides a 24V DC voltage to the slave device 20 and a 3.3V DC voltage to the first RS485 transceiver circuit 12 through a DC-DC step-down converter. It should be further noted that the power supply module 11 also receives an external 24V DC voltage and, through its built-in... The isolation transformer transmits the 24V DC voltage required by the system, isolating interference between the internal and external 24V DC voltages. One set of wire pairs (e.g., orange-white, orange) of the first Ethernet shielded twisted pair 30 and the second Ethernet shielded twisted pair 40 is used to transmit RS485 differential signals, and the other set of wire pairs (e.g., green-white, green) is used to transmit DC power. Preferably, both the first Ethernet shielded twisted pair 30 and the second Ethernet shielded twisted pair 40 are at least shielded twisted pairs that meet the CAT5E specification. For example, they can be Cat5e shielded twisted pairs, Cat6e shielded twisted pairs, or Cat6A shielded twisted pairs, etc.

[0043] Specifically, the DC-DC converter circuit 22 includes a DC-DC step-down chip U1, a transient voltage suppressor diode TV1, a first input filter capacitor C1, a second input filter capacitor C2, a third input filter capacitor C3, an enable pull-up resistor R1, a bootstrap capacitor C4, a first inductor L1, a first feedback resistor R2, a second feedback resistor R3, a third feedback resistor R4, a compensation capacitor C5, a first output filter capacitor C6, a second output filter capacitor C7, and a reverse protection diode D1. One end of the transient voltage suppressor diode TV1 is connected to the DC-DC step-down chip. The VIN pin of chip U1 is connected to the second RJ45 network port 23, and the other end is grounded. One end of the first input filter capacitor C1 and the second input filter capacitor C2 are both connected to the VIN pin of the DC-DC step-down chip U1, and the other end of each is grounded. The enable terminal pull-up resistor R1 is connected between the VIN pin and the EN pin of the DC-DC step-down chip U1. One end of the third input filter capacitor C3 is connected to the EN pin of the DC-DC step-down chip U1, and the other end is grounded. The two ends of the bootstrap capacitor C4 are connected to the... The BOOT and SW pins of the DC-DC step-down chip U1 are connected. The first end of the first inductor L1 is connected to the SW pin of the DC-DC step-down chip U1, and the second end is connected to the second RS485 transceiver circuit 21 to provide a 3.3V DC voltage. One end of the first feedback resistor R2 is connected to the second end of the first inductor L1, and the other end is connected to the second feedback resistor R3. The other end of the second feedback resistor R3 is connected to the FB pin of the DC-DC step-down chip U1. One end of the third feedback resistor R4 is connected to the FB pin of the DC-DC step-down chip U1, and the other end is grounded. One end of the compensation capacitor C5 is connected to the second end of the first inductor L1, and the other end is connected to the FB pin of the DC-DC step-down chip U1. One end of the first output filter capacitor C6 and the second output filter capacitor C7 are each connected to the second end of the first inductor L1, and the other end of each is grounded. The positive terminal of the anti-reverse diode D1 is connected to the transient voltage suppression diode TV1, and the other end is connected to the VIN pin of the DC-DC step-down chip U1.

[0044] The DC-DC step-down chip U1 is model SGM61410XN6G / TR.

[0045] Specifically, the first RS485 transceiver circuit 12 and the second RS485 transceiver circuit 21 have the same structure, both including an RS485 transceiver chip U2, a common-mode inductor Z1, a first pull-up resistor R6, a second pull-up resistor R7, a first pull-down resistor R8, a second pull-down resistor R9, an input filter circuit, a current-limiting resistor R10, and a third output filter capacitor C8. The third and fourth terminals of the common-mode inductor Z1 are connected to pins B and A of the RS485 transceiver chip U2, respectively. The first pull-up resistor R6 is connected to pin A of the RS485 transceiver chip U2, and the other end is connected to a 3.3V DC voltage. One end of the first pull-down resistor R8 is connected to pin B of the RS485 transceiver chip U2, and the other end is grounded. One end of the second pull-up resistor R7 is connected to pin RO of the RS485 transceiver chip U2, and the other end is connected to a 3.3V DC voltage. One end of the second pull-down resistor R9 is connected to pins RE and DE of the RS485 transceiver chip U2, and the other end is grounded. One end of the input filter circuit is connected to pin VCC of the RS485 transceiver chip U2, and the other end is connected to a 3.3V DC voltage. One end of the current-limiting resistor R10 is connected to pin RO of the RS485 transceiver chip U2. One pin is connected, and the other end is connected to the third output filter capacitor C8. The other end of the third output filter capacitor C8 is grounded. The first and second ends of the common-mode inductor Z1 of the first RS485 transceiver circuit 12 are both connected to the first RJ45 network port 13. The first and second ends of the common-mode inductor Z1 of the second RS485 transceiver circuit 21 are both connected to the second RJ45 network port 23. The first RS485 transceiver circuit 12 receives 3.3V DC voltage from the power supply module 11, and the second RS485 transceiver circuit 21 receives 3.3V DC voltage from the DC-DC conversion circuit 22. The input filtering circuit includes a second inductor L2, a fourth input filter capacitor C9, a fifth input filter capacitor C10, and a sixth input filter capacitor C11. One end of the second inductor L2 is connected to a 3.3V DC voltage, and the other end is connected to the VCC pin of the RS485 transceiver chip U2. One end of each of the fourth input filter capacitor C9, the fifth input filter capacitor C10, and the sixth input filter capacitor C11 is connected to the VCC pin of the RS485 transceiver chip U2, and the other end of each is grounded. Preferably, a matching resistor R11 is connected between the third and fourth ends of the common-mode inductor Z1.

[0046] The RS485 transceiver chip U2 is model number TPT75176H-SO1R.

[0047] In summary, the RS485 communication and power supply integrated system based on Ethernet shielded twisted pair provided in this application embodiment transmits RS485 communication signals and DC power simultaneously using a first Ethernet shielded twisted pair and a second Ethernet shielded twisted pair, enhancing anti-interference capabilities. Furthermore, it eliminates the need for separate wiring for communication and power lines, simplifying wiring and reducing cable and labor costs. Connecting master and slave control devices via RJ45 ports and Ethernet shielded twisted pair eliminates the need for crimping and wiring, reducing construction difficulty and further lowering labor costs. This solves the technical problems of existing RS485 communication systems that use separate power and communication cables, resulting in high wiring complexity, high cable and labor costs, difficulties in later maintenance, and poor anti-interference capabilities.

[0048] The above provides a detailed description of the RS485 communication and power supply integrated system based on Ethernet shielded twisted pair provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An integrated RS485 communication and power supply system based on Ethernet shielded twisted-pair cable, characterized in that, It includes a master control device and N slave control devices, where N≥1 and N is an integer; The main control device includes a first RS485 transceiver circuit and a power supply module, wherein the power supply module is electrically connected to the first RS485 transceiver circuit. The slave device includes a second RS485 transceiver circuit and a DC-DC converter circuit, wherein the DC-DC converter circuit is electrically connected to the second RS485 transceiver circuit. When N=1, the master control device is connected to the slave control device through a first Ethernet shielded twisted pair cable; When N≥2, the master control device and one of the slave control devices are connected via a first Ethernet shielded twisted pair cable, and the N slave control devices are sequentially chained together via a second Ethernet shielded twisted pair cable.

2. The RS485 communication and power supply integrated system based on Ethernet shielded twisted pair according to claim 1, characterized in that, The master control device is provided with a first RJ45 network port, and the slave control device is provided with a second RJ45 network port and a third RJ45 network port; The first RS485 transceiver circuit and the power supply module are both electrically connected to the first RJ45 network port, and the second RS485 transceiver circuit, the DC-DC conversion circuit and the third RJ45 network port are all electrically connected to the second RJ45 network port. The master control device and the slave control device are connected through the first RJ45 network port, the first Ethernet shielded twisted pair cable and the second RJ45 network port. The two ends of the second Ethernet shielded twisted pair cable are respectively connected to the third RJ45 network port of the slave control device in the front stage and the second RJ45 network port of the slave control device in the back stage.

3. The RS485 communication and power supply integrated system based on Ethernet shielded twisted pair according to claim 2, characterized in that, The DC-DC conversion circuit includes a DC-DC step-down chip, a transient voltage suppression diode, a first input filter capacitor, a second input filter capacitor, a third input filter capacitor, an enable pull-up resistor, a bootstrap capacitor, a first inductor, a first feedback resistor, a second feedback resistor, a third feedback resistor, a compensation capacitor, a first output filter capacitor, and a second output filter capacitor. One end of the transient voltage suppressor diode is connected to the VIN pin of the DC-DC step-down chip and the second RJ45 network port, and the other end is grounded. One end of both the first and second input filter capacitors is connected to the VIN pin of the DC-DC step-down chip, and the other end of each is grounded. A pull-up resistor is connected between the VIN and EN pins of the DC-DC step-down chip. One end of the third input filter capacitor is connected to the EN pin of the DC-DC step-down chip, and the other end is grounded. The two ends of the bootstrap capacitor are connected to the BOOT and SW pins of the DC-DC step-down chip. The first end of the first inductor is connected to the DC-DC step-down chip. The SW pin of the step-down chip is connected, and the second terminal is connected to the second RS485 transceiver circuit to provide a 3.3V DC voltage. One end of the first feedback resistor is connected to the second terminal of the first inductor, and the other end is connected to the second feedback resistor. The other end of the second feedback resistor is connected to the FB pin of the DC-DC step-down chip. One end of the third feedback resistor is connected to the FB pin of the DC-DC step-down chip, and the other end is grounded. One end of the compensation capacitor is connected to the second terminal of the first inductor, and the other end is grounded. One end of each of the first output filter capacitor and the second output filter capacitor is connected to the second terminal of the first inductor, and the other end of each is grounded.

4. The RS485 communication and power supply integrated system based on Ethernet shielded twisted pair according to claim 3, characterized in that, The DC-DC conversion circuit also includes a reverse protection diode, the positive terminal of which is connected to the transient voltage suppression diode, and the other end of which is connected to the VIN pin of the DC-DC step-down chip.

5. The RS485 communication and power supply integrated system based on Ethernet shielded twisted pair according to claim 3, characterized in that, The DC-DC step-down chip is SGM61410XN6G / TR.

6. The RS485 communication and power supply integrated system based on Ethernet shielded twisted pair according to claim 2, characterized in that, The first RS485 transceiver circuit and the second RS485 transceiver circuit have the same structure, both including an RS485 transceiver chip, a common mode inductor, a first pull-up resistor, a second pull-up resistor, a first pull-down resistor, a second pull-down resistor, an input filter circuit, a current limiting resistor, and a third output filter capacitor. The third and fourth terminals of the common-mode inductor are connected to pins B and A of the RS485 transceiver chip, respectively. The first pull-up resistor is connected to pin A of the RS485 transceiver chip, and the other end is connected to a 3.3V DC voltage. One end of the first pull-down resistor is connected to pin B of the RS485 transceiver chip, and the other end is grounded. One end of the second pull-up resistor is connected to pin RO of the RS485 transceiver chip, and the other end is connected to a 3.3V DC voltage. One end of the second pull-down resistor is connected to pins RE and DE of the RS485 transceiver chip, and the other end is grounded. One end of the input filter circuit is connected to pin VCC of the RS485 transceiver chip, and the other end is connected to a 3.3V DC voltage. One end of the current-limiting resistor is connected to pin RO of the RS485 transceiver chip, and the other end is connected to the third output filter capacitor. The other end of the third output filter capacitor is grounded. The first and second ends of the common-mode inductor of the first RS485 transceiver circuit are both connected to the first RJ45 network port, and the first and second ends of the common-mode inductor of the second RS485 transceiver circuit are both connected to the second RJ45 network port.

7. The RS485 communication and power supply integrated system based on Ethernet shielded twisted pair according to claim 6, characterized in that, The RS485 transceiver chip is TPT75176H-SO1R.

8. The RS485 communication and power supply integrated system based on Ethernet shielded twisted pair according to claim 6, characterized in that, The input filtering circuit includes a second inductor, a fourth input filtering capacitor, a fifth input filtering capacitor, and a sixth input filtering capacitor; One end of the second inductor is connected to a 3.3V DC voltage, and the other end is connected to the VCC pin of the RS485 transceiver chip. One end of each of the fourth, fifth, and sixth input filter capacitors is connected to the VCC pin of the RS485 transceiver chip, and the other end of each is grounded.

9. The RS485 communication and power supply integrated system based on Ethernet shielded twisted pair according to claim 1, characterized in that, Both the first Ethernet shielded twisted pair and the second Ethernet shielded twisted pair are shielded twisted pairs that meet at least the CAT5E specification.

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