485 isolation device based on photoelectric isolation circuit

Abstract

The utility model provides a 485 isolation device based on a photoelectric isolation circuit, and belongs to the technical field of 485 communication. The problem that when an existing 485 isolator is used underground, communication reliability is poor is solved. Comprising an intrinsic safety shell, a guide rail terminal is arranged on the back face of the intrinsic safety shell, and a wiring terminal is arranged on the front face of the intrinsic safety shell and connected with field equipment and a process control system / control system. A control circuit board is arranged in the intrinsic safety shell, an isolation circuit and an intrinsic safety power supply circuit are integrated on the control circuit board, the intrinsic safety power supply circuit supplies power to the isolation circuit, the isolation circuit comprises a first RS-485 chip, a first voltage reduction chip, a photoelectric coupling circuit, a second voltage reduction chip and a second RS-485 chip which are connected in sequence, and the photoelectric coupling circuit is connected with the first RS-485 chip. Wherein the input end of the first RS-485 chip is connected with a first communication end, the output end of the second RS-485 chip is connected with a second communication end, and the photoelectric coupling circuit is composed of a first photoelectric coupler and a second photoelectric coupler which are connected in parallel; the down-hole 485 communication device is applied to down-hole 485 communication.

Description

Technical Field

[0001] The utility model provides a 485 isolation device based on a photoelectric isolation circuit, belonging to the technical field of 485 isolators. Background Art

[0002] Mining-grade 485 isolators are widely used in industrial mining environments, addressing the isolation and interference mitigation requirements of RS-485 communications. Mining environments are often subject to high levels of electromagnetic interference, vibration, and temperature fluctuations, necessitating reliable communication solutions to ensure stable data transmission.

[0003] The RS-485 communication interface is a physical layer bus design standard commonly used in industry and instrumentation, offering advantages such as multi-node communication, long-distance transmission, and strong anti-interference capabilities. However, in mining environments, due to the presence of power equipment, high-voltage lines, and other factors, communication signals are susceptible to electromagnetic interference, resulting in data transmission errors or loss.

[0004] To address these issues, mining-grade 485 isolators were developed. By employing specialized circuit design and technology, they achieve high-strength electrical isolation in 485 communications, effectively isolating noise and interference between the signal and power supply. This ensures data stability and reliability during transmission.

[0005] Mining-grade 485 isolators also feature a wide operating temperature range, typically adapting to ambient temperatures ranging from -40°C to +85°C. They are also vibration-resistant, enabling them to operate normally in harsh vibration environments. Furthermore, mining-grade 485 isolators are typically corrosion- and dust-resistant, adapting to the corrosion and dust issues present in mining environments.

[0006] Mine-grade 485 isolators have a wide range of applications. They can be used in mine monitoring systems to monitor parameters such as temperature, humidity, and gas concentration in real time to ensure safe operation. They can also be used in safety systems such as fire alarms and video surveillance systems to ensure personnel safety. In the field of automated control, mine-grade 485 isolators are also a common communication device used to enable data transmission and control between various devices.

[0007] In short, mining 485 isolator technology plays an important role in the mining industry. It ensures stable data transmission and system reliability by providing electrical isolation and anti-interference capabilities, providing a safe and efficient communication solution for the mining industry.

[0008] However, the current mining 485 isolators generally only achieve signal isolation through photoelectric isolation or electromagnetic isolation, and do not achieve effective isolation between the signal and the power supply, resulting in poor communication reliability when used underground. Utility Model Content

[0009] In order to solve the problem of poor communication reliability of existing 485 isolators when used underground, the utility model proposes a 485 isolation device based on a photoelectric isolation circuit. The purpose is to achieve high-strength electrical isolation in the 485 isolator through hardware improvement or improvement of the combined connection of hardware modules and / or circuits to ensure communication reliability.

[0010] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: a 485 isolation device based on a photoelectric isolation circuit, comprising an intrinsically safe housing, a guide rail terminal being provided on the back of the intrinsically safe housing, and a wiring terminal being provided on the front of the housing, the wiring terminal comprising a first communication terminal and a second communication terminal, which can be used as an input terminal and an output terminal to connect a field device and a process control system / control system respectively;

[0011] A control circuit board is provided inside the intrinsically safe housing, and an isolation circuit and an intrinsically safe power supply circuit are integrated on the control circuit board. The intrinsically safe power supply circuit supplies power to the isolation circuit. The isolation circuit includes a first RS-485 chip, a first step-down chip, a photoelectric coupling circuit, a second step-down chip and a second RS-485 chip connected in sequence, wherein the input end of the first RS-485 chip is connected to the first communication end, and the output end of the second RS-485 chip is connected to the second communication end, and the photoelectric coupling circuit is composed of a first photoelectric coupler and a second photoelectric coupler connected in parallel; the driver input end GND pins of the first RS-485 chip and the second RS-485 chip are both grounded, and the receiver output end RO of the first RS-485 chip controls the transceiver enable of the second RS-485 chip via the second photoelectric coupler, and the receiver output end RO of the second RS-485 chip controls the transceiver enable of the first RS-485 chip via the first photoelectric coupler;

[0012] The intrinsically safe power supply circuit includes a current limiting circuit and a voltage step-down circuit. The output signal of the current limiting circuit is connected to the driver end of the second RS-485 chip. The voltage step-down circuit reduces the input 12-36V DC voltage to the 5V voltage required by the isolation circuit.

[0013] The connection structure of the isolation circuit is as follows:

[0014] The RO pin of the first RS-485 chip is connected in series with the current-limiting resistor R1 and then connected to the Vf- pin of the second photocoupler. The RE and DE pins of the first RS-485 chip are short-circuited and connected to the SW pin of the first buck chip and one end of the capacitor C9. The other end of the capacitor C9 is connected to one end of the capacitor C7 and one end of the capacitor C8 and then to ground. The DI pin of the first RS-485 chip is connected to the FB pin of the first buck chip, the VO pin of the first photocoupler, and one end of the resistor R11. The other end of the resistor R11 is connected to one end of the capacitor C10. The other end of the capacitor C10 is connected to the GND pin of the first buck chip and then to the GNDB ground wire. The IN pin of the first buck chip is connected to the VCCB circuit. Source; the receiver A input terminal of the first RS-485 chip is connected in parallel to one end of the pull-up resistor R15 and one end of the resistor R14, the other end of the resistor R15 is connected to the VCCB power supply, the other end of the resistor R14 is connected in parallel to the cathode of the diodes DR1 and DR2, and pin 2 of the first communication terminal, the anodes of the diodes DR1 and DR2 are connected in parallel to one end of the resistor R13 and then to pin 1 of the first communication terminal, the other end of the resistor R13 is connected in parallel to one end of the pull-down resistor R12 and the receiver B input terminal of the first RS-485 chip, and the other end of the resistor R12 is connected to the GNDB ground wire; the VCC pin of the first RS-485 chip is connected to the VCCB power supply, and the GND pin of the first RS-485 chip 1 is connected to the GNDB ground wire;

[0015] The VE pin of the first photocoupler is connected in parallel to the VCC pin and then to the Vf+ pin of the second photocoupler, and both are connected to the VCCB power supply. The Vf- pin of the first photocoupler is connected in series with the pull-up resistor R8 and then to the RO pin of the second RS-485 chip. The Vf+ pin of the first photocoupler is connected in parallel to the VCC pin, VE pin, one end of the resistor R9, and one end of the capacitor C6, and then to the VCC power supply. The other end of the resistor R9 is connected in parallel to the VO pin of the second photocoupler, the FB pin of the second step-down chip, and the DI pin of the second RS-485 chip. The other end of the capacitor C6 is connected in parallel to the VO pin of the second photocoupler, the FB pin of the second step-down chip, and the DI pin of the second RS-485 chip. One end is connected in parallel to the GND pin of the second step-down chip, one end of capacitor C5 is connected to the GNDA ground wire, the other end of capacitor C5 is connected in parallel to the RE pin and DE pin of the second RS-485 chip, and then to the SW pin of the second step-down chip; the IN pin of the second step-down chip is connected in parallel to the +Vin pin of the power module, one end of capacitor C4, and one end of capacitor C3, the other end of capacitor C4 is connected in parallel to the other end of capacitor C3, and then to the -Vin pin of the power module, the -Vout pin of the power module is connected to the GNDB ground wire, and the +Vout pin of the power module is connected in parallel to the other end of capacitor C7 and the other end of capacitor C8;

[0016] The receiver B1 of the second RS-485 chip 6 is connected in parallel to one end of the resistor R7 and one end of the resistor R5, the other end of the resistor R7 is grounded, the other end of the resistor R5 is connected in parallel to the anode of the diode DR3 and pin 1 of the second communication port 8, the receiver A1 of the second RS-485 chip 6 is connected in parallel to one end of the resistor R6 and one end of the resistor R4, the other end of the resistor R6 is connected to the VCC power supply, the other end of the resistor R4 is connected in parallel to the anode of the diode DR4 and pin 2 of the second communication port 8, and the cathodes of the diodes DR3 and DR4 are both grounded.

[0017] The models of the first RS-485 chip and the second RS-485 chip are SP485E.

[0018] The models of the first photoelectric coupler and the second photoelectric coupler are HCPL-0601.

[0019] The models of the first buck chip and the second buck chip are LM2577.

[0020] The model of the power module is B0505S-1W.

[0021] The control circuit board adopts a PCB board, and the electrical clearance at the intrinsically safe plug-in on the PCB board is greater than 2mm.

[0022] The PCB board is made of FR-4 epoxy resin material.

[0023] The beneficial effects of the present invention over the prior art are as follows: the 485 isolation device based on the photoelectric isolation circuit provided by the present invention realizes the isolation and transmission of input and output electrical signals by setting two parallel photoelectric couplers, has a high-strength electrical isolation function, can effectively isolate the noise and interference between the signal and the power supply, protects the intrinsically safe circuit in the hazardous area by current limiting and voltage limiting, realizes electromagnetic isolation between the potential explosive gas environment and the safe area in the system, and provides a stable and reliable communication environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below with reference to the accompanying drawings:

[0025] Figure 1 This is a schematic diagram of the structure of the device of the utility model Figure 1 ;

[0026] Figure 2 The structure of the device of the utility model is shown as follows Figure 2 ;

[0027] Figure 3 This is a schematic diagram of the circuit structure of the device of the utility model;

[0028] Figure 4This is a schematic diagram of the isolation circuit of the device of the utility model;

[0029] Figure 5 This is a schematic diagram of the power supply circuit of the device of the utility model;

[0030] Figure 6 This is a schematic diagram of the front structure of the PCB board in the device of the utility model;

[0031] Figure 7 This is a schematic diagram of the reverse structure of the PCB board in the device of the utility model;

[0032] In the figure: 100 is the intrinsically safe housing, 200 is the wiring terminal, 300 is the guide rail terminal, 1 is the first RS-485 chip, 2 is the first step-down chip, 3 is the first photoelectric coupler, 4 is the second photoelectric coupler, 5 is the first communication terminal, 6 is the second RS-485 chip, 7 is the second step-down chip, 8 is the second communication terminal, 9 is the current limiting circuit, and 10 is the step-down circuit. DETAILED DESCRIPTION

[0033] like Figures 1 to 7 As shown, this utility model provides a 485 isolation device based on a photoelectric isolation circuit, suitable for signal transmission between field devices and process control systems / control systems. It can be used to connect field devices installed in potentially explosive gas environments, protecting intrinsically safe circuits in hazardous areas through current and voltage limiting, and achieving electromagnetic isolation between the potentially explosive gas environment and the safe area of the system.

[0034] The isolation device of the present invention includes an intrinsically safe housing 100. A guide rail terminal 300 is provided on the rear surface of the intrinsically safe housing 100, allowing the device to be mounted on a standard 35mm guide rail. A wiring terminal 200 is provided on the front surface of the housing 100, allowing the device to be installed between a field device and a process control system / control system. The wiring terminal 200 is provided with a first communication terminal 5 and a second communication terminal 8, which can serve as an input and output, respectively, connecting the field device and the process control system / control system via a 485 communication line.

[0035] A control circuit board is provided inside the intrinsically safe housing 100. The control circuit board adopts a PCB board. The circuit board thickness of the PCB board is ≥1.5mm, the minimum line width of the conductor is ≥0.3mm, the CTI is >175V, the printed circuit board size is: 80×74 (mm), the line spacing is greater than 1mm, the line thickness is ≥0.35um, and the electrical clearance at the intrinsically safe connector is greater than 2mm. The material of the PCB board is FR-4 epoxy resin, and the copper cladding has a thickness of 0.35mm on both sides. After welding is completed, the welding surface is sprayed with insulating varnish twice.

[0036] The PCB board integrates an isolation circuit and an intrinsically safe power supply circuit. The isolation circuit includes a first RS-485 chip 1, a first step-down chip 2, a photoelectric coupling circuit, a second step-down chip 7, and a second RS-485 chip 6 connected in sequence. The input end of the first RS-485 chip 1 is connected to the first communication terminal 5, and the output end of the second RS-485 chip 6 is connected to the second communication terminal 8. The photoelectric coupling circuit consists of a first photoelectric coupler 3 and a second photoelectric coupler 4 connected in parallel.

[0037] The RO pin of the first RS-485 chip 1 is connected in series with the current-limiting resistor R1 and then connected to the Vf- pin of the second photocoupler 4. The RE and DE pins of the first RS-485 chip 1 are short-circuited and connected to the SW pin of the first buck chip 2 and one end of the capacitor C9. The other end of the capacitor C9 is connected in parallel to one end of the capacitor C7 and one end of the capacitor C8 and then to ground. The DI pin of the first RS-485 chip 1 is connected in parallel to the FB pin of the first buck chip 2, the VO pin of the first photocoupler 3, and one end of the resistor R11. The other end of the resistor R11 is connected to one end of the capacitor C10. The other end of the capacitor C10 is connected in parallel to the GND pin of the first buck chip 2 and then to the GNDB ground wire. The IN pin of the first buck chip 2 is connected to VCCB. Power supply; the receiver A input terminal of the first RS-485 chip 1 is connected in parallel to one end of the pull-up resistor R15 and one end of the resistor R14, the other end of the resistor R15 is connected to the VCCB power supply, the other end of the resistor R14 is connected in parallel to the cathodes of the diodes DR1 and DR2 and pin 2 of the first communication terminal 5, the anodes of the diodes DR1 and DR2 are connected in parallel to one end of the resistor R13 and then to pin 1 of the first communication terminal 5, the other end of the resistor R13 is connected in parallel to one end of the pull-down resistor R12 and the receiver B input terminal of the first RS-485 chip 1, and the other end of the pull-down resistor R12 is connected to the GNDB ground wire; the VCC pin of the first RS-485 chip 1 is connected to the VCCB power supply, and the GND pin of the first RS-485 chip 1 is connected to the GNDB ground wire.

[0038] The VE pin of the first photocoupler 3 is connected in parallel to the VCC pin and then to the Vf+ pin of the second photocoupler 4, and both are connected to the VCCB power supply. The Vf- pin of the first photocoupler 3 is connected in series with the pull-up resistor R8 and then to the RO pin of the second RS-485 chip 6. The Vf+ pin of the first photocoupler 3 is connected in parallel to the VCC pin, the VE pin, one end of the resistor R9, and one end of the capacitor C6 of the second photocoupler 4 and then to the VCC power supply. The other end of the resistor R9 is connected in parallel to the VO pin of the second photocoupler 4, the FB pin of the second step-down chip 7, and the DI pin of the second RS-485 chip 6. The capacitor C The other end of 6 is connected in parallel to the GND pin of the second step-down chip 7, and one end of the capacitor C5 is connected to the GNDA ground wire. The other end of the capacitor C5 is connected in parallel to the RE pin and DE pin of the second RS-485 chip 6 and then to the SW pin of the second step-down chip 7; the IN pin of the second step-down chip 7 is connected in parallel to the +Vin pin of the power module, one end of the capacitor C4, and one end of the capacitor C3. The other end of the capacitor C4 is connected in parallel to the other end of the capacitor C3 and then to the -Vin pin of the power module. The -Vout pin of the power module is connected to the GNDB ground wire. The +Vout pin of the power module is connected in parallel to the other end of the capacitor C7 and the other end of the capacitor C8. The receiver B1 of the second RS-485 chip 6 is connected in parallel to one end of the resistor R7 and one end of the resistor R5, the other end of the resistor R7 is grounded, the other end of the resistor R5 is connected in parallel to the anode of the diode DR3 and pin 1 of the second communication port 8, the receiver A1 of the second RS-485 chip 6 is connected in parallel to one end of the resistor R6 and one end of the resistor R4, the other end of the resistor R6 is connected to the VCC power supply, the other end of the resistor R4 is connected in parallel to the anode of the diode DR4 and pin 2 of the second communication port 8, and the cathodes of the diodes DR3 and DR4 are both grounded.

[0039] The driver input GND pins of the first RS-485 chip 1 and the second RS-485 chip 6 are grounded, and the receiver output RO controls the transmitting and receiving enable of the RS-485 chip on the other side via a photoelectric coupler.

[0040] The first photocoupler 3 and the second photocoupler 4 are of model HCPL-0601; they are mainly used to realize the isolation and transmission of input and output electrical signals in the circuit, and can transmit electrical signals between different circuit systems. At the same time, they can effectively isolate interference and noise between circuits, thereby improving the stability and reliability of the circuit.

[0041] The first RS-485 chip 1 and the second RS-485 chip 6 are both SP485E. They function as transceivers within the circuit, including one driver and one receiver. They also feature fail-safe circuitry. Their low-slew-rate drivers reduce EMI and reflections caused by improperly terminated cables, enabling error-free data transmission at speeds up to 500 kbps. They also include +4 kV ESD protection.

[0042] The intrinsically safe power supply circuit includes a current limiting circuit and a voltage step-down circuit. Figure 3 The power supply block diagram of the 485 isolator circuit of the present invention is shown. Frame 9 shows the current-limiting circuit. Resistors R4 and R6 act as current-limiting resistors to prevent excessive input current. The input signal, after passing through the current-limiting resistors, is connected to pins 6 and 7 of the second RS-485 chip 6. Frame 10 shows the step-down circuit, which reduces the input voltage within the 12V-36V range to the 5V required by the circuit and also serves as a voltage limiter.

[0043] This utility model isolates and outputs RS485 digital communication signals from the hazardous area to the safe area, while also providing intrinsically safe power to instruments in the hazardous area. Serial communication and networking are enabled via a dedicated communication interface. This utility model protects the intrinsically safe circuits in the hazardous area through current and voltage limiting, achieving electromagnetic isolation between the potentially explosive gas environment and the safe area.

[0044] The first communication terminal 5 of the utility model is a signal input terminal, the input A / B signal is an RS485 digital communication signal, the transmission control mode is half-duplex, the second communication terminal 8 is a signal output terminal, the output A1 / B1 signal is an RS485 digital communication signal, the transmission delay is ≤5μs, and the signal transmission rate is ≤56kbps; the power supply (V+, V-) of the device of the utility model is: 18VDC-60V DC.

[0045] Through special circuit design and technology, the utility model provides an RS485 isolator with simple circuit structure and high reliability. It has high-strength electrical isolation function, can effectively isolate noise and interference between signals and power supply, and provides a stable and reliable communication environment for underground field equipment and control systems.

[0046] Regarding the specific structure of the present invention, it should be noted that the connection relationship between the various component modules adopted in the present invention is definite and feasible. Except for the special instructions in the embodiments, the specific connection relationship can bring about corresponding technical effects and solve the technical problems raised by the present invention without relying on the execution of the corresponding software program. The components, modules, models of specific components appearing in the present invention, the connection methods between each other, and the conventional usage methods and expected technical effects brought about by the above-mentioned technical features, except for the specific instructions, all belong to the disclosed contents in patents, journal articles, technical manuals, technical dictionaries, and textbooks that can be obtained by technical personnel in this field before the application date, or belong to the existing technologies such as conventional technology and common knowledge in this field, and there is no need to elaborate, so that the technical solution provided in this case is clear, complete, and feasible, and the corresponding physical products can be reproduced or obtained based on this technical means.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A 485 isolation device based on a photoelectric isolation circuit, comprising an intrinsically safe housing, characterized in that: The back of the intrinsically safe housing is provided with a guide rail terminal, and the front of the intrinsically safe housing is provided with a wiring terminal, the wiring terminal includes a first communication terminal and a second communication terminal, which can be used as an input terminal and an output terminal to connect the field device and the control system respectively; A control circuit board is provided inside the intrinsically safe housing, and an isolation circuit and an intrinsically safe power supply circuit are integrated on the control circuit board. The intrinsically safe power supply circuit supplies power to the isolation circuit. The isolation circuit includes a first RS-485 chip, a first step-down chip, a photoelectric coupling circuit, a second step-down chip and a second RS-485 chip connected in sequence, wherein the input end of the first RS-485 chip is connected to the first communication end, and the output end of the second RS-485 chip is connected to the second communication end, and the photoelectric coupling circuit is composed of a first photoelectric coupler and a second photoelectric coupler connected in parallel; the driver input end GND pins of the first RS-485 chip and the second RS-485 chip are both grounded, and the receiver output end RO of the first RS-485 chip controls the transceiver enable of the second RS-485 chip via the second photoelectric coupler, and the receiver output end RO of the second RS-485 chip controls the transceiver enable of the first RS-485 chip via the first photoelectric coupler; The intrinsically safe power supply circuit includes a current limiting circuit and a voltage step-down circuit. The output signal of the current limiting circuit is connected to the driver end of the second RS-485 chip. The voltage step-down circuit reduces the input 12-36V DC voltage to the 5V voltage required by the isolation circuit.

2. The 485 isolation device based on the photoelectric isolation circuit according to claim 1, characterized in that: The connection structure of the isolation circuit is as follows: The RO pin of the first RS-485 chip is connected in series with the current-limiting resistor R1 and then connected to the Vf- pin of the second photocoupler. The RE and DE pins of the first RS-485 chip are short-circuited and connected to the SW pin of the first buck chip and one end of the capacitor C9. The other end of the capacitor C9 is connected to one end of the capacitor C7 and one end of the capacitor C8 and then to ground. The DI pin of the first RS-485 chip is connected to the FB pin of the first buck chip, the VO pin of the first photocoupler, and one end of the resistor R11. The other end of the resistor R11 is connected to one end of the capacitor C10. The other end of the capacitor C10 is connected to the GND pin of the first buck chip and then to the GNDB ground wire. The IN pin of the first buck chip is connected to the VCCB circuit. Source; the receiver A input terminal of the first RS-485 chip is connected in parallel to one end of the pull-up resistor R15 and one end of the resistor R14, the other end of the resistor R15 is connected to the VCCB power supply, the other end of the resistor R14 is connected in parallel to the cathode of the diodes DR1 and DR2, and pin 2 of the first communication terminal, the anodes of the diodes DR1 and DR2 are connected in parallel to one end of the resistor R13 and then to pin 1 of the first communication terminal, the other end of the resistor R13 is connected in parallel to one end of the pull-down resistor R12 and the receiver B input terminal of the first RS-485 chip, and the other end of the resistor R12 is connected to the GNDB ground wire; the VCC pin of the first RS-485 chip is connected to the VCCB power supply, and the GND pin of the first RS-485 chip 1 is connected to the GNDB ground wire; The VE pin of the first photocoupler is connected in parallel to the VCC pin and then to the Vf+ pin of the second photocoupler, and both are connected to the VCCB power supply. The Vf- pin of the first photocoupler is connected in series with the pull-up resistor R8 and then to the RO pin of the second RS-485 chip. The Vf+ pin of the first photocoupler is connected in parallel to the VCC pin, VE pin, one end of the resistor R9, and one end of the capacitor C6, and then to the VCC power supply. The other end of the resistor R9 is connected in parallel to the VO pin of the second photocoupler, the FB pin of the second step-down chip, and the DI pin of the second RS-485 chip. The other end of the capacitor C6 is connected in parallel to the VO pin of the second photocoupler, the FB pin of the second step-down chip, and the DI pin of the second RS-485 chip. One end is connected in parallel to the GND pin of the second step-down chip, one end of capacitor C5 is connected to the GNDA ground wire, the other end of capacitor C5 is connected in parallel to the RE pin and DE pin of the second RS-485 chip, and then to the SW pin of the second step-down chip; the IN pin of the second step-down chip is connected in parallel to the +Vin pin of the power module, one end of capacitor C4, and one end of capacitor C3, the other end of capacitor C4 is connected in parallel to the other end of capacitor C3, and then to the -Vin pin of the power module, the -Vout pin of the power module is connected to the GNDB ground wire, and the +Vout pin of the power module is connected in parallel to the other end of capacitor C7 and the other end of capacitor C8; The receiver B1 of the second RS-485 chip 6 is connected in parallel to one end of the resistor R7 and one end of the resistor R5, the other end of the resistor R7 is grounded, the other end of the resistor R5 is connected in parallel to the anode of the diode DR3 and pin 1 of the second communication port, the receiver A1 of the second RS-485 chip 6 is connected in parallel to one end of the resistor R6 and one end of the resistor R4, the other end of the resistor R6 is connected to the VCC power supply, the other end of the resistor R4 is connected in parallel to the anode of the diode DR4 and pin 2 of the second communication port, and the cathodes of the diodes DR3 and DR4 are both grounded.

3. The 485 isolation device based on the photoelectric isolation circuit according to claim 2, characterized in that: The models of the first RS-485 chip and the second RS-485 chip are SP485E.

4. The 485 isolation device based on the photoelectric isolation circuit according to claim 2, characterized in that: The models of the first photoelectric coupler and the second photoelectric coupler are HCPL-0601.

5. The 485 isolation device based on the photoelectric isolation circuit according to claim 2, characterized in that: The models of the first buck chip and the second buck chip are LM2577.

6. The 485 isolation device based on the photoelectric isolation circuit according to claim 2, characterized in that: The model of the power module is B0505S-1W.

7. A 485 isolation device based on a photoelectric isolation circuit according to any one of claims 1 to 6, characterized in that: The control circuit board adopts a PCB board, and the electrical clearance at the intrinsically safe plug-in on the PCB board is greater than 2mm.

8. The 485 isolation device based on the photoelectric isolation circuit according to claim 7, characterized in that: The PCB board is made of FR-4 epoxy resin material.

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