Long-distance PLC transmission communication device

Abstract

The invention discloses a long-distance PLC (Programmable Logic Controller) transmission communication device, which comprises an original network machine room, a two-wire POE (Power Over Ethernet) exchange system and telephone lines which are arranged before N years and lead to each floor or each building in different areas, the two-wire PLCPOE switch is connected with the network equipment through the long-distance PLC transmission interface module; the long-distance PLC transmission interface module comprises a combination hub interface CN3, lightning protection tubes T2 and T3 and a piezoresistor R11; due to the fact that the junction capacitance of the TVS tube is too large, the TVS tube may absorb or reflect part of signals, signal distortion or attenuation is caused, and particularly in high-speed communication, the influence is more obvious, so that the TVS protection tube is removed, and the T2 and T3 lightning protection tubes are added for lightning stroke, surge and EFT protection.

Description

Technical Field

[0001] The present invention relates to the technical field of long-distance PLC transmission communication for the renovation of old building corridor lines, and specifically provides a long-distance PLC transmission communication device. Background Art

[0002] With the rapid development of technology, household electrical appliances are becoming more and more intelligent. For buildings that have been constructed, telephone lines and TV lines have already been laid. However, our devices are all digital, high-definition, and high-speed network devices. When upgrading and renovating existing buildings, office buildings, and residential communities to use these modern devices, it takes a lot of time and money to find professionals to lay network cables and optical fibers. The previous buildings may not have reserved space in their designs, which brings great difficulties to subsequent wiring. It not only affects the aesthetics but also may pose potential safety hazards or inconvenience for maintenance. To solve the above problems, in existing products, digital network cables or optical fibers are pulled to the building network computer room, connected to a router, and then to a directional intelligent PLC POE switch. Using the original telephone lines or 220V power supply lines, the analog signals converted from digital signals are transmitted to each floor or each user. At the end-user side, the analog signal is then converted back into a digital signal, and the user can plug and play, providing excellent connectivity and communication functions for the user.

[0003] However, these telephone lines and power lines may often be laid outside the building wall, beside the strong electricity indoors, or beside the motors in the elevator shaft. Therefore, TVS tubes need to be placed at the 24-way interfaces of the PLC POE switch for protection. In AC or DC system lines, TVS tubes can effectively suppress the surge voltage generated by power switches or power grid fluctuations, eliminate the interference caused by bus switches, ensure the stability of data and control buses, prevent electrostatic discharge, and when the circuit is connected to inductive load devices, TVS tubes can suppress instantaneous pulse voltages and prevent integrated circuits from being damaged by instantaneous pulses. However, it is found in actual use that when using TVS tubes to protect interfaces and devices, the maximum transmission distance of a single interface is about 500 meters, which can meet the normal use of users. However, in actual applications, there are also PLC devices with a transmission distance of more than 1000 meters. When using existing products to test the input signals of terminal devices with a tester, as Figure 4 shown, it is found that the transmitted signal is distorted and the signal quality deteriorates. Summary of the Invention

[0004] To solve the defects existing in the prior art, the present invention provides a long-distance PLC transmission communication device.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] A long-distance PLC transmission communication device of the present invention includes an original network computer room, a 2-wire POE switching system, and telephone lines laid N years ago and leading to each floor or each different area building; the 2-wire POE switching system includes two connected two-wire PLC POE switches; the previous two-wire PLC POE switch converts the digital signal of the external network into an analog signal, adds the analog signal to the telephone line, and transmits the encrypted analog signal to the corresponding floor or building through the telephone line; and uses the latter two-wire PLC POE switch to convert the analog signal into a digital network signal; then transmits the digital network signal to the network device at the back end;

[0007] The two-wire PLC POE switch is connected to the network device through a long-distance PLC transmission interface module;

[0008] The long-distance PLC transmission interface module includes a socket interface CN3, lightning protection tubes T2 and T3, and a varistor R11;

[0009] The negative electrodes 1 and 2 pins of the connection socket interface CN3 are connected to the second pin of the lightning protection tube T2, and the first pin of the lightning protection tube T2 is connected to the metal shell ground PE. The 1.2 pins of the connection socket interface CN3 are simultaneously connected to the RJ11 network interfaces CN4, CN5, and CN6 and the negative pole of the interface signal line. The negative electrodes 1 and 2 pins of the connection socket interface CN3 are connected to the second tube of the varistor R11. The first pin of the varistor R11 is connected to the positive signal lines 3 and 4 pins of the connection socket interface CN3 and is simultaneously connected to the first pin of the lightning protection tube T3; the second pin of the lightning protection tube T3 is connected to the metal ground PE;

[0010] A resettable fuse group is connected between the positive signal lines 3 and 4 pins of the connection socket interface CN3 and the positive signal wires of the R11 network interfaces CN4, CN5, CN6, and 24 interfaces.

[0011] As a preferred technical solution of the present invention, the two-wire PLC POE switch includes a network cable access interface module, a main control CPU module, an ADC module, a DAC module, and a network voltage transformation module;

[0012] The network cable access interface module is connected to the main control CPU module. The main control CPU module is connected to the network voltage transformation module through the ADC module and the DAC module. The output end of the network voltage transformation module is connected with an output interface module.

[0013] As a preferred technical solution of the present invention, the ADC module includes bidirectional TVS tubes D401, D402, D403; resistors R401, R402, and R403; capacitors C401, C402, C403, C404, C404, C406, C407;

[0014] One end of the inductor L403 is connected to one end of the bidirectional TVS tubes D401 and D402, and at the same time is connected to the main control CPU module through the ADC_RXP network identifier. The other end of the bidirectional TVS tube D401 is grounded. The other end of the inductor L403 is connected to one end of the inductor L406, and at the same time is connected to one end of the capacitors C402 and C405. The other end of the capacitor C402 is connected to one end of the inductor L402. The other end of the inductor L402 is connected to the inductor L405, and at the same time is connected to one end of the capacitors C404 and C401.

[0015] The other end of the capacitor C401 is connected to one end of the inductor L401. The other end of the inductor L401 is connected to one end of the resistor R401, and at the same time is connected to one end of the resistor R402, one end of the inductor L404, and one end of the capacitor C403. And the other end of the inductor L401 is connected to the network voltage transformation module through the CPL_RXP network identifier.

[0016] The other end of the resistor R401 is grounded. The other end of the resistor R402 is connected to the other end of the inductor L404, the other end of the capacitor C403, one end of the inductor L407, and one end of the resistor R403. The other end of the inductor L407 is connected to the network voltage transformation module through the CPL_RXN network identifier.

[0017] The other end of the resistor R403 is grounded. The other end of the inductor L407 is connected to one end of the capacitor C406. The other end of the capacitor C406 is connected to one end of the inductor L405, one end of the L408, and at the same time is connected to one end of the capacitor C404.

[0018] The other end of the inductor L408 is connected to one end of the capacitor C407. The other end of the capacitor C407 is connected to one end of the inductor L406 and one end of the capacitor L409. At the same time, the other end of the capacitor C407 is also connected to one end of the capacitor C405. The other end of the inductor L409 is connected to one end of the bidirectional TVS tube D402 and one end of the bidirectional TVS tube D403. At the same time, the other end of the inductor L409 is connected to the 66th pin of the main control CPU U301 through the ADC_RXN network label. The other end of the TVS tube D403 is grounded.

[0019] As a preferred technical solution of the present invention, the DAC module includes a PLC transmitting chip U401, resistors R404, R405, R406, R407, R408, R409, R410, R411, R412; capacitors C411, C412, C413, C414, C415, C416, C417, C418; bidirectional TVS tubes D404, D405, D406.

[0020] One end of the capacitor C412 is connected to the main control CPU module through the DAC_TXN network identifier. The other end of the capacitor C412 is connected to one end of the resistor R408, one end of the resistor R405, and is also connected to the 3rd pin of the PLC transmitting chip U401. The other end of the resistor R408 is connected to one end of the resistor R410, one end of the resistor R407, one end of the capacitor C413, and one end of the resistor R409.

[0021] The other end of the resistor R407 is connected to the positive pole of the 12V power supply. One end of the capacitor C413 is grounded. The other end of the resistor R409 is grounded. One end of the capacitor C417 is connected to the main control CPU module through the DAC_TXP network identifier. The other end of the capacitor C417 is connected to one end of the resistor R410 and is also connected to the PLC transmitting chip U401.

[0022] The 1st, 5th, 6th, 12th, 4th, 15th, 17th, and 7th pins of the PLC transmitting chip U401 are grounded. The 2nd pin of the PLC transmitting chip U401 is connected to one end of the resistor R404 and one end of the resistor R405. The other end of the resistor R404 is connected to the 16th pin of the PLC transmitting chip U401 and one end of the resistor R406. The other end of the resistor R405 is connected to one end of the capacitor C416. The other end of the capacitor C416 is connected to the 11th pin of the PLC transmitting chip U401 and is also connected to one end of the resistor R413. The other end of the resistor R413 is connected to the 13th pin of the PLC transmitting chip U401 and one end of the resistor R411.

[0023] The 14th pin of the PLC transmitting chip U401 is connected to the 12V power supply and is also connected to one end of the capacitor C414 and one end of the capacitor C415. The other end of the capacitor C414 and the other end of the capacitor C415 are grounded. One end of the resistor R406 is connected to one end of the capacitor C411. The other end of the capacitor C411 is connected to one end of the bidirectional TVS tube D404 and one end of the bidirectional TVS tube D405. The other end of the capacitor C411 is also connected to the network voltage conversion module through the CPL_TXN network identifier.

[0024] The other end of the bidirectional TVS tube D404 is grounded. The other end of the resistor R411 is connected to one end of the capacitor C418. The other end of the capacitor C418 is connected to the other end of the bidirectional diode D405 and is also connected to one end of the bidirectional TVS tube D406. The other end of the capacitor C418 is also connected to the network voltage conversion module through the CPL_TXP network identifier. The other end of the bidirectional TVS tube D406 is grounded.

[0025] As a preferred technical solution of the present invention, the network voltage conversion module includes a network transformer T401, capacitors C420 and C421, resistors R414 and R416; a bidirectional diode D407 and a socket CN401;

[0026] The first pin of the network transformer T401 is connected to one end of the bidirectional diode D407 and at the same time to one end of the capacitor C420. The other end of the capacitor C420 is connected to one end of the resistor R414, and the other end of the resistor R414 is connected to the 3rd and 4th pins of the socket CN401. The fourth pin of the network transformer T401 is connected to the other end of the bidirectional diode D407 and at the same time to one end of the capacitor C421. The other end of the capacitor C421 is connected to one end of the resistor R416, and the other end of the resistor R416 is connected to the 1st and 2nd pins of the socket C401.

[0027] The beneficial effects of the present invention are:

[0028] 1. By removing the TVS protection tube in the original device in this long-distance PLC transmission communication device, since the video and audio transmitted between the PLC POE router and the terminal device are affected by the TVS tube, there is a certain relationship between the junction capacitance of the TVS tube itself and the signal transmission rate. Specifically, there is a certain connection between the junction capacitance value of the TVS tube and the communication rate. In a communication system, especially in a high-speed communication system such as PLC, the junction capacitance of the TVS tube will affect the transmission quality and speed of the signal. This is because the junction capacitance stores charges, and when the signal passes through, these stored charges will affect the transmission speed and efficiency of the signal. If the junction capacitance of the TVS tube is too large, it may absorb or reflect part of the signal, resulting in signal distortion or attenuation, especially in high-speed communication, this effect is more obvious. Therefore, when selecting a TVS tube, it is necessary to consider the matching between its junction capacitance value and the rate requirements of the communication system to ensure that the signal can be transmitted efficiently and accurately; with the current production process and materials, the junction capacitance of the TVS tube body will not be less than 1NF; the junction capacitance of the TVS tube will affect the transmission quality and speed of the signal. This is because the junction capacitance stores charges, and when the signal passes through, these stored charges will affect the transmission speed and efficiency of the signal. If the junction capacitance of the TVS tube is too large, it may absorb or reflect part of the signal, resulting in signal distortion or attenuation, especially in high-speed communication, this effect is more obvious. By removing the TVS protection tube and adding lightning protection tubes T2 and T3 for lightning strike, surge, and EFT protection.

[0029] 2. In this long-distance PLC transmission communication device, the ADC input passes through a third-order band-pass filter. The frequency range that can pass through is 2 MHz - 90 MHz frequency signals, removing other unnecessary frequency noises. The first-order filtering components are L403, L406, L409, and C405; the differential signal passes through C402 and C407 to the second-order filtering components L402, L405, L408, and C404; it passes through C401 and C406 to the third-order filtering components L401, L404, L407, and C403; among them, the bidirectional TVS diodes D401, D402, and D403 prevent the surge voltage on the differential signal and protect the analog input pins of the main control chip.

[0030] 3. In this long-distance PLC transmission communication device, the U401 chip is a power line single-ended differential line driver, which can communicate in PLC and EOC (Ethernet Over Cable) applications. The driver chip is designed to drive heavy-line loads while maintaining the required high linearity PLC / EOC link, converting the total transmit signal power of 15.5 dBm into a 75 Ohm line load. The driver achieves 40 dB average MTPR distortion across the entire spectrum up to 96 MHz. The supported frequency range is from 1.8 MHz to 96 MHz; it is designed for industrial applications; the AFE_RXEN control switch controls the transmission on and off of U401. R412 is the control signal current-limiting resistor, and its function is to prevent the control signal current from being too large and damaging the U401 chip; C419 is the control signal filtering capacitor, and their function is to prevent signal mutations and prevent misoperations; the digital signal sent by the main control passes through the C412 and C417 capacitors for filtering and then inputs to U401. U401 converts the digital signal into an analog signal amplified by the PLC protocol and transmits it. R406, R411, C411, and C418 are the output filtering circuits; the dual TVS diodes D404, D405, and D406 prevent common-mode and differential-mode surge voltages and protect the U401 chip.

[0031] 3. In this long-distance PLC transmission communication device, the network transformer T401 realizes the isolation and conversion of high-voltage signals and low-voltage signals; the high-voltage end and the low-voltage end are not grounded together, realizing the isolation of high-voltage signals and low-voltage signals without affecting the conversion. Pins 1 and 4 of the T401 network transformer are the high-voltage signal ends of the PLC signal; pins 6 and 7 of the T401 network transformer are the output pins of the DAC module, and pins 5 and 8 of T401 are the input pins of the ADC signal. Description of the Drawings

[0032] The drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation to the present invention.

[0033] In the drawings:

[0034] Figure 1 It is a system schematic diagram of a long-distance PLC transmission communication device of the present invention;

[0035] Figure 2 It is a structural schematic diagram of a two-wire PLCPOE switch of a long-distance PLC transmission communication device of the present invention;

[0036] Figure 3 It is a circuit structural schematic diagram of a long-distance PLC transmission interface module of a long-distance PLC transmission communication device of the present invention;

[0037] Figure 4 It is an effect diagram of signal distortion in an existing communication device;

[0038] Figure 5 It is a circuit schematic diagram of an ADC module of a long-distance PLC transmission communication device of the present invention;

[0039] Figure 6 It is a circuit schematic diagram of a DAC module of a long-distance PLC transmission communication device of the present invention;

[0040] Figure 7 It is a circuit schematic diagram of a network voltage transformation module of a long-distance PLC transmission communication device of the present invention;

[0041] Figure 8 It is a signal sampling schematic diagram of a long-distance PLC transmission communication device of the present invention.

[0042] In the figure: 1. Network computer room; 2. Two-wire PLCPOE switch; 201. Network cable access interface module; 202. Main control CPU module; 203. ADC module; 204. DAC module; 205. Network voltage transformation module; 3. Long-distance PLC transmission interface module. Specific embodiments

[0043] The following is a description of the preferred embodiments of the present invention with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not used to limit the present invention.

[0044] Embodiment: As Figure 1-8 shown, a long-distance PLC transmission communication device of the present invention includes an original network computer room 1, a 2-wire POE switching system, and telephone lines laid N years ago and leading to each floor or each different area building; the 2-wire POE switching system includes two connected two-wire PLCPOE switches 2;

[0045] The previous two-wire PLCPOE switch 2 converts the digital signal from the external network into an analog signal, adds the analog signal to the telephone line, and transmits the encrypted analog signal to the corresponding floor or building through the telephone line; and uses the subsequent two-wire PLCPOE switch 2 to convert the analog signal into a digital network signal; then transmits the digital network signal to the network equipment at the back end;

[0046] The two-wire PLCPOE switch 2 is connected to the network equipment through the long-distance PLC transmission interface module 3;

[0047] The long-distance PLC transmission interface module 3 includes a socket interface CN3, lightning protection tubes T2 and T3, and a varistor R11;

[0048] The negative electrodes 1 and 2 of the socket interface CN3 are connected to the second pin of the lightning protection tube T2, and the first pin of the lightning protection tube T2 is connected to the metal shell ground PE. The 1 and 2 pins of the socket interface CN3 are simultaneously connected to the RJ11 network interfaces CN4, CN5, and CN6 and the negative electrode of the interface signal line. The negative electrodes 1 and 2 of the socket interface CN3 are connected to the second pin of the varistor R11, and the first pin of the varistor R11 is connected to the positive signal lines 3 and 4 of the socket interface CN3 and is simultaneously connected to the first pin of the lightning protection tube T3; the second pin of the lightning protection tube T3 is connected to the metal ground PE;

[0049] A resettable fuse group is connected between the positive signal lines 3 and 4 of the socket interface CN3 and the positive signal wires of the R11 network interfaces CN4, CN5, CN6, and 24 interfaces. The video and audio transmitted between our PLC POE router and the terminal device are affected TVS tube There is a certain relationship between the junction capacitance of the TVS tube itself and the signal transmission rate. Specifically, there is a certain connection between the junction capacitance value of the TVS tube and the communication rate. In a communication system, especially in a high-speed communication system such as PLC, the junction capacitance of the TVS tube will affect the transmission quality and speed of the signal. This is because the junction capacitance stores charge, and when the signal passes through, these stored charges will affect the transmission speed and efficiency of the signal. If the junction capacitance of the TVS tube is too large, it may absorb or reflect part of the signal, resulting in signal distortion or attenuation, especially in high-speed communication, this effect is more obvious. Therefore, when selecting a TVS tube, it is necessary to consider the matching between its junction capacitance value and the rate requirements of the communication system to ensure that the signal can be transmitted efficiently and accurately.

[0050] The PLC POE switch is used in industrial scenarios. Therefore, it needs to pass the certification for surge, with a common mode of + / -1KV and a differential mode of + / -2KV. The operating voltage of the PLC power line is 48V DC. The TVS tube selected is of the BV-SMCJ48CA SMC package, with a power of over 1500W; the voltage is 48V, and the power is over 1500W. The junction capacitance of the TVS tube itself reaches over 1NF. In the SMC package, with the current production process and materials, the junction capacitance of the TVS tube body will not be less than 1NF; the junction capacitance of the TVS tube will affect the transmission quality and speed of the signal. This is because the junction capacitance stores charges, and when a signal passes through, these stored charges will affect the transmission speed and efficiency of the signal. If the junction capacitance of the TVS tube is too large, it may absorb or reflect part of the signal, resulting in signal distortion or attenuation, especially in high-speed communication, this effect is more obvious. Therefore, when the transmission distance of the PLC POW switch is greater than 500 meters, a requirement of over 1000 meters is needed. The D3, D4, and D5 TVS tubes in the existing interface board cannot meet the design requirements; these three protection tubes need to be removed. However, when removing the TVS protection tubes, lightning strike, surge, and EFT protection are still required. Add T2 and T3 lightning protection tubes to the interface board schematic diagram. The model is SMDC-75V, with a lightning strike resistance of 5KV, an AC discharge current of 5A, and the junction capacitance of the lightning protection tube is less than 0.5PF. Such a small junction capacitance does not affect the transmission quality and speed of the signal. It can protect our PLC equipment for a point-to-point transmission distance of up to 1000 meters.

[0051] The two-wire PLC POE switch 2 includes a network cable access interface module 201, a main control CPU module 202, an ADC module 203, a DAC module 204, and a network voltage transformation module 205;

[0052] The network cable access interface module 201 is connected to the main control CPU module 202. The main control CPU module 202 is connected to the network voltage transformation module 205 via the ADC module 203 and the DAC module 204. An output interface module 206 is connected to the output end of the network voltage transformation module 205.

[0053] Among them, the ADC module 203 includes bidirectional TVS tubes D401, D402, D403; resistors R401, R402, and R403; capacitors C401, C402, C403, C404, C404, C406, C407; inductors L401, L402, L403, L404, L405, L406, L407, L408;

[0054] One end of the inductor L403 is connected to one end of the bidirectional TVS diode D401 and the bidirectional TVS diode D402, and is simultaneously connected to the main control CPU module through the ADC_RXP network identifier. The other end of the bidirectional TVS diode D401 is grounded. The other end of the L403 inductor is connected to one end of the inductor L406, and is simultaneously connected to one end of the capacitor C402 and the capacitor C405. The other end of the capacitor C402 is connected to one end of the inductor L402. The other end of the inductor L402 is connected to the inductor L405, and is simultaneously connected to one end of the capacitor C404 and the capacitor C401.

[0055] The other end of the capacitor C401 is connected to one end of the inductor L401. The other end of the inductor L401 is connected to one end of the resistor R401, and is simultaneously connected to one end of the resistor R402, one end of the inductor L404, and one end of the capacitor C403. And the other end of the inductor L401 is connected to the network voltage transformation module 205 through the CPL_RXP network identifier.

[0056] The other end of the resistor R401 is grounded. The other end of the resistor R402 is connected to the other end of the inductor L404, the other end of the capacitor C403, one end of the inductor L407, and one end of the resistor R403. The other end of the inductor L407 is connected to the network voltage transformation module 205 through the CPL_RXN network identifier.

[0057] The other end of the resistor R403 is grounded. The other end of the inductor L407 is connected to one end of the capacitor C406. The other end of the capacitor C406 is connected to one end of the inductor L405, one end of the L408, and is simultaneously connected to one end of the capacitor C404.

[0058] The other end of the inductor L408 is connected to one end of the capacitor C407. The other end of the capacitor C407 is connected to one end of the inductor L406 and one end of the capacitor L409. And the other end of the capacitor C407 is also connected to one end of the capacitor C405. The other end of the inductor L409 is connected to one end of the bidirectional TVS diode D402 and one end of the bidirectional TVS diode D403. And the other end of the inductor L409 is connected to the 66th pin of the main control CPU U301 through the ADC_RXN network label. The other end of the TVS diode D403 is grounded. The ADC input passes through a third-order band-pass filter, and the passable frequency range is 2MHZ - 90MHZ frequency signals, removing other unnecessary frequency noises. The first-order filtering is L403, L406, L409, C405; the differential signal passes through C402, C407 to the second-order filtering L402, L405, L408, C404; passes through C401, C406 to the third-order filtering L401, L404, L407, C403; among them, the bidirectional TVS diodes D401, D402, D403 are used to prevent the surge voltage on the differential signal and protect the analog input pins of the main control chip.

[0059] The DAC module 204 includes a PLC transmitting chip U401, resistors R404, R405, R406, R407, R408, R409, R410, R411, R412; capacitors C411, C412, C413, C414, C415, C416, C417, C418; bidirectional TVS diodes D404, D405, D406;

[0060] One end of the capacitor C412 is connected to the main control CPU module 202 through the DAC_TXN network identifier. The other end of the capacitor C412 is connected to one end of the resistor R408 and one end of the resistor R405, and is also connected to the 3rd pin of the PLC transmitting chip U401. The other end of the resistor R408 is connected to one end of the resistor R410, one end of the resistor R407, one end of the capacitor C413, and one end of the resistor R409;

[0061] The other end of the resistor R407 is connected to the positive pole of the 12V power supply. One end of the capacitor C413 is grounded. The other end of the resistor R409 is grounded. One end of the capacitor C417 is connected to the main control CPU module 202 through the DAC_TXP network identifier. The other end of the capacitor C417 is connected to one end of the resistor R410 and is also connected to the PLC transmitting chip U401;

[0062] The 1st, 5th, 6th, 12th, 4th, 15th, 17th, and 7th pins of the PLC transmitting chip U401 are grounded. The 2nd pin of the PLC transmitting chip U401 is connected to one end of the resistor R404 and one end of the resistor R405. The other end of the resistor R404 is connected to the 16th pin of the PLC transmitting chip U401 and one end of the resistor R406. The other end of the resistor R405 is connected to one end of the capacitor C416. The other end of the capacitor C416 is connected to the 11th pin of the PLC transmitting chip U401 and is also connected to one end of the resistor R413. The other end of the resistor R413 is connected to the 13th pin of the PLC transmitting chip U401 and one end of the resistor R411;

[0063] The 14th pin of the PLC transmitting chip U401 is connected to the 12V power supply and is also connected to one end of the capacitor C414 and one end of the capacitor C415. The other end of the capacitor C414 and the other end of the capacitor C415 are grounded. One end of the resistor R406 is connected to one end of the capacitor C411. The other end of the capacitor C411 is connected to one end of the bidirectional TVS diode D404 and one end of the bidirectional TVS diode D405. The other end of the capacitor C411 is also connected to the network voltage conversion module 205 through the CPL_TXN network identifier;

[0064] The other end of the bidirectional TVS diode D404 is grounded. The other end of the resistor R411 is connected to one end of the capacitor C418. The other end of the capacitor C418 is connected to the other end of the bidirectional diode D405 and is also connected to one end of the bidirectional TVS diode D406. The other end of the capacitor C418 is simultaneously connected to the network voltage conversion module 205 through the CPL_TXP network identifier; the other end of the bidirectional TVS diode D406 is grounded. The U401 chip is a power line single-ended differential line driver, which can communicate in PLC and EOC (Ethernet Over Cable) applications. The driver chip is designed to drive heavy line loads while maintaining the required high linearity of the PLC / EOC link, converting the total transmitted signal power of 15.5 dBm into a 75 Ohm line load. The driver achieves 40 dB average MTPR distortion across the entire spectrum up to 96 MHz. The supported frequency range is from 1.8 MHz to 96 MHz; it is designed for industrial applications; the AFE_RXEN control switch controls the transmission on and off of U401. R412 is the control signal current-limiting resistor, which is used to prevent the control signal current from being too large and damaging the U401 chip; C419 is the control signal filtering capacitor, and their function is to prevent signal mutations and misoperations; the digital signal sent by the main control is filtered by the capacitors C412 and C417 and then input into U401. U401 converts the digital signal into an analog signal of the PLC protocol and amplifies and transmits it. R406, R411, C411, and C418 are the output filter circuits; the dual TVS diodes D404, D405, and D406 are used to prevent common-mode and differential-mode surge voltages and protect the U401 chip.

[0065] The network voltage conversion module 205 includes a network transformer T401, capacitors C420 and C421, resistors R414 and R416; a bidirectional diode D407 and a socket CN401; the network transformer T401 realizes the isolation and conversion of high-voltage signals and low-voltage signals; the high-voltage end and the low-voltage end are not grounded together, realizing the isolation of high-voltage signals and low-voltage signals without affecting the conversion. Pins 1 and 4 of the T401 network transformer are the high-voltage signal terminals of the PLC signal; pins 6 and 7 of the T401 network transformer are the output pins of the DAC module, and pins 5 and 8 of the T401 are the input pins of the ADC signal.

[0066] The first pin of the network transformer T401 is connected to one end of the bidirectional diode D407 and also to one end of the capacitor C420. The other end of the capacitor C420 is connected to one end of the resistor R414, and the other end of the resistor R414 is connected to the third and fourth pins of the socket CN401. The fourth pin of the network transformer T401 is connected to the other end of the bidirectional diode D407 and also to one end of the capacitor C421. The other end of the capacitor C421 is connected to one end of the resistor R416, and the other end of the resistor R416 is connected to the first and second pins of the socket C401. The invention adopts differential output. The differential circuit has a very high amplification ability for differential-mode signals because the differential-mode signals received by the two input terminals of the differential pair are directly amplified without being affected by the common-mode signals. It has a very good suppression ability for common-mode signals. When the common-mode part of the two input signals changes, the common-mode feedback network will adjust the bias of the differential pair so that the voltage at the output terminal remains stable. The input impedance is relatively high, which helps to reduce the load of the signal source, improve the stability of the circuit, and improve the transmission quality of the signal.

[0067] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A long-distance PLC transmission communication device, including the original network computer room (1), a 2-wire POE switching system, and telephone lines laid N years ago that lead to each floor or each building in different areas; the 2-wire POE switching system includes two connected two-wire PLC POE switches (2); characterized in that: The previous two-wire PLC POE switch (2) converts the digital signal of the external network into an analog signal, adds the analog signal to the telephone line, and transmits the encrypted analog signal to the corresponding floor or building through the telephone line; and uses the latter two-wire PLC POE switch (2) to convert the analog signal into a digital network signal; then transmits the digital network signal to the network device at the back end; The two-wire PLC POE switch (2) is connected to the network device through a long-distance PLC transmission interface module (3); The long-distance PLC transmission interface module (3) includes a socket interface CN3, lightning protection tubes T2 and T3, and a varistor R11; The negative electrodes 1 and 2 of the connection socket interface CN3 are connected to the second pin of the lightning protection tube T2, and the first pin of the lightning protection tube T2 is connected to the metal shell ground PE. The 1.2 pins of the connection socket interface CN3 are simultaneously connected to the RJ11 network interfaces CN4, CN5, and CN6 and the negative electrode of the interface signal line. The negative electrodes 1 and 2 of the connection socket interface CN3 are connected to the second pin of the varistor R11, and the first pin of the varistor R11 is connected to the positive signal lines 3 and 4 of the connection socket interface CN3 and is simultaneously connected to the first pin of the lightning protection tube T3; The second pin of the lightning protection tube T3 is connected to the metal ground PE; There is a resettable fuse group connected between the positive signal lines 3 and 4 of the connection socket interface CN3 and the positive signal wires of the R11 network interfaces CN4, CN5, CN6, and 24 interfaces.

2. The long-distance PLC transmission communication device according to claim 1, characterized in that, The two-wire PLC POE switch (2) includes a network cable access interface module (201), a main control CPU module (202), an ADC module (203), a DAC module (204), and a network voltage conversion module (205); The network cable access interface module (201) is connected to the main control CPU module (202), the main control CPU module (202) is connected to the network voltage conversion module (205) through the ADC module (203) and the DAC module (204), and the output end of the network voltage conversion module (205) is connected with an output interface module (206).

3. The long-distance PLC transmission and communication device according to claim 1, characterized in that, The ADC module (203) includes bidirectional TVS tubes D401, D402, D403; resistors R401, R402, and R403; capacitors C401, C402, C403, C404, C404, C406, C407; inductors L401, L402, L403, L404, L405, L406, L407, L408; One end of the inductor L403 is connected to one end of the bidirectional TVS diode D401 and the bidirectional TVS diode D402, and is simultaneously connected to the main control CPU module through the ADC_RXP network identifier. The other end of the bidirectional TVS diode D401 is grounded. The other end of the inductor L403 is connected to one end of the inductor L406, and is simultaneously connected to one end of the capacitor C402 and the capacitor C405. The other end of the capacitor C402 is connected to one end of the inductor L402. The other end of the inductor L402 is connected to the inductor L405, and is simultaneously connected to one end of the capacitor C404 and the capacitor C401. The other end of the capacitor C401 is connected to one end of the inductor L401. The other end of the inductor L401 is connected to one end of the resistor R401, and is simultaneously connected to one end of the resistor R402, one end of the inductor L404, and one end of the capacitor C403. And the other end of the inductor L401 is connected to the network transformer module (205) through the CPL_RXP network identifier. The other end of the resistor R401 is grounded. The other end of the resistor R402 is connected to the other end of the inductor L404, the other end of the capacitor C403, one end of the inductor L407, and one end of the resistor R403. The other end of the inductor L407 is connected to the network transformer module (205) through the CPL_RXN network identifier. The other end of the resistor R403 is grounded. The other end of the inductor L407 is connected to one end of the capacitor C406. The other end of the capacitor C406 is connected to one end of the inductor L405, one end of the L408, and is simultaneously connected to one end of the capacitor C404. The other end of the inductor L408 is connected to one end of the capacitor C407. The other end of the capacitor C407 is connected to one end of the inductor L406 and one end of the capacitor L409. And the other end of the capacitor C407 is also connected to one end of the capacitor C405. The other end of the inductor L409 is connected to one end of the bidirectional TVS diode D402 and one end of the bidirectional TVS diode D403. And the other end of the inductor L409 is connected to the 66th pin of the main control CPU U301 through the ADC_RXN network label. The other end of the TVS diode D403 is grounded.

4. A long-distance PLC transmission and communication device according to claim 1, characterized in that, The DAC module (204) includes the PLC transmitting chip U401, resistors R404, R405, R406, R407, R408, R409, R410, R411, R412; capacitors C411, C412, C413, C414, C415, C416, C417, C418; bidirectional TVS diodes D404, D405, D406. One end of the capacitor C412 is connected to the main control CPU module (202) through the DAC_TXN network identifier. The other end of the capacitor C412 is connected to one end of the resistor R408, one end of the resistor R405, and is simultaneously connected to the 3rd pin of the PLC transmitting chip U401. The other end of the resistor R408 is connected to one end of the resistor R410, one end of the resistor R407, one end of the capacitor C413, and one end of the resistor R409. The other end of the resistor R407 is connected to the positive pole of the 12V power supply, one end of the capacitor C413 is grounded, the other end of the resistor R409 is grounded, one end of the capacitor C417 is connected to the main control CPU module (202) through the DAC_TXP network identifier, the other end of the capacitor C417 is connected to one end of the resistor R410, and is also connected to the PLC transmitting chip U401 at the same time; The 1st, 5th, 6th, 12th, 4th, 15th, 17th, and 7th pins of the PLC transmitting chip U401 are grounded; the 2nd pin of the PLC transmitting chip U401 is connected to one end of the resistor R404 and one end of the resistor R405. The other end of the resistor R404 is connected to the 16th pin of the PLC transmitting chip U401 and one end of the resistor R406. The other end of the resistor R405 is connected to one end of the capacitor C416. The other end of the capacitor C416 is connected to the 11th pin of the PLC transmitting chip U401 and is also connected to one end of the resistor R413 at the same time. The other end of the resistor R413 is connected to the 13th pin of the PLC transmitting chip U401 and one end of the resistor R411; The 14th pin of the PLC transmitting chip U401 is connected to the 12V power supply and is also connected to one end of the capacitor C414 and one end of the capacitor C415. The other ends of the capacitor C414 and the capacitor C415 are grounded; one end of the resistor R406 is connected to one end of the capacitor C411. The other end of the capacitor C411 is connected to one end of the bidirectional TVS tube D404 and one end of the bidirectional TVS tube D405. At the same time, the other end of the capacitor C411 is also connected to the network voltage transformation module (205) through the CPL_TXN network identifier; The other end of the bidirectional TVS tube D404 is grounded. The other end of the resistor R411 is connected to one end of the capacitor C418. The other end of the capacitor C418 is connected to the other end of the bidirectional diode D405 and is also connected to one end of the bidirectional TVS tube D406. The other end of the capacitor C418 is also connected to the network voltage transformation module (205) through the CPL_TXP network identifier; the other end of the bidirectional TVS tube D406 is grounded.

5. A long-distance PLC transmission and communication device according to claim 2, characterized in that, The network voltage transformation module (205) includes a network transformer T401, capacitors C420 and C421, resistors R414 and R416; a bidirectional diode D407 and a socket CN401; The 1st pin of the network transformer T401 is connected to one end of the bidirectional diode D407 and is also connected to one end of the capacitor C420. The other end of the capacitor C420 is connected to one end of the resistor R414. The other end of the resistor R414 is connected to the 3rd and 4th pins of the socket CN401. The 4th pin of the network transformer T401 is connected to the other end of the bidirectional diode D407 and is also connected to one end of the capacitor C421. The other end of the capacitor C421 is connected to one end of the resistor R416. The other end of the resistor R416 is connected to the 1st and 2nd pins of the socket C401.

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