High-protection-performance RS485 circuit capable of remotely controlling circuit resistor access

Abstract

The invention provides a high-protection-performance RS485 circuit capable of remotely controlling circuit resistor access. The high-protection-performance RS485 circuit comprises an MCU module, a power module, a signal isolation circuit module, an RS485 chip peripheral circuit module, an RS485 protection circuit module and an external port module. The MCU controls the working state of the circuit, the signal isolation module isolates signals between the MCU and the RS485 chip, the RS485 chip peripheral circuit realizes signal transceiving, the protection circuit protects a signal line from interference, and the external port module is connected with an external communication network. According to the invention, the access of the terminating resistor and the current-limiting resistor can be remotely controlled, the anti-interference performance and the protection capability of the RS485 circuit are enhanced, the strict requirements of the power industry on the safety regulation and EMC test are met, and the communication stability and reliability are improved.

Description

Technical Field

[0001] The present invention relates to the field of serial communication circuits, and more specifically, to a high-protection RS485 circuit capable of remotely controlling circuit resistance access. Background Art

[0002] The RS485 protocol has been widely used in industrial automation, communication, agriculture, smart home and environmental monitoring due to its advantages of long-distance communication capability, high anti-interference, multi-point access capability and easy integration and maintenance. However, there are some common problems in the existing RS485 circuit design. For the 120R termination resistor, common design methods include direct loading on the circuit, connecting to the circuit through a shorting cap, and some improvement methods, such as using a control relay, a triode or a MOS tube to control the access of the termination resistor. These methods either lead to a decrease in signal quality, or require manual operation and easily introduce static electricity to damage the chip, or have problems such as large space occupation, reduced driving ability or increased cost. At the same time, there are also problems with the access of the current limiting resistor. Failure to access may cause component damage or circuit failure, while access may weaken the driving ability of RS485 and reduce the number of mounted devices. In addition, the existing RS485 circuit has only partial protection in terms of electromagnetic compatibility, such as adding TVS and GDT on the AB line, but in the test requirements of the power industry, these designs are still insufficient in terms of safety protection level and electromagnetic compatibility interference filtering.

[0003] In the process of implementing the embodiments of the present invention, the inventors found that there are at least the following problems or defects in the prior art: the existing RS485 circuit design lacks flexibility in the access of remote control termination resistors and current limiting resistors, and at the same time fails to meet the high standards of the power industry in terms of protection performance, resulting in insufficient stability and reliability in harsh environments. Summary of the invention

[0004] The present invention provides a high protection performance RS485 circuit capable of remotely controlling circuit resistance access, comprising: The MCU module is used to control the working state of the entire circuit, and its output is connected to the input end of the signal isolation circuit module, and the input end receives the output signal from the signal isolation circuit module; The power module provides a stable power supply for the entire circuit, and its output end is respectively connected to the power input end of the MCU module, the signal isolation circuit module, the RS485 chip peripheral circuit module, the RS485 protection circuit module and the external port module; A signal isolation circuit module is used to isolate the signal between the MCU module and the RS485 chip peripheral circuit module, wherein the input end is connected to the output end of the MCU module, and the output end is connected to the input end of the RS485 chip peripheral circuit module; The RS485 chip peripheral circuit module is used to realize the transmission and reception of RS485 signals, and its input end is connected to the output end of the signal isolation circuit module, and the output end is connected to the input end of the RS485 protection circuit module; RS485 protection circuit module, used to protect RS485 signal line from static electricity, surge and other interference, its input end is connected to the output end of RS485 chip peripheral circuit module, and its output end is connected to the input end of external port module; An external port module is used to connect to an external RS485 communication network, an input end of which is connected to an output end of the RS485 protection circuit module, and an output end of which is connected to the external RS485 communication network; The MCU module controls the optocoupler relay through the SEL signal to remotely control the access of the 120R termination resistor. When the SEL signal activates the optocoupler relay, the output end of the optocoupler relay is turned on, so that the 120R termination resistor is connected to the RS485 line; conversely, when the SEL signal does not activate the optocoupler relay, the output end of the optocoupler relay is cut off and the 120R termination resistor is disconnected.

[0005] Furthermore, the RS485 protection circuit module includes: Switch U1, with its pin 1 connected to pin 6 of RS485 chip U24, and its pin 2 connected to pin 7 of U24; Common mode inductor T4, pin 2 thereof is connected to one end of resistor R773, the other end of R773 is connected to pin 4 of switch U1, pin 1 of T4 is connected to one end of resistor R772, the other end of R772 is connected to pin 5 of switch U1; The digital isolation chip U22, whose pin 7 is connected to the pin 3 of the switch U1; Magnetic beads FB88 and FB89 are connected to pins 2 and 1 of external terminal J31 respectively; The optocoupler relay has its pin 1 connected to pin 1 of the MCU, pin 2 is grounded, pin 3 is connected to one end of resistor R165, the other end of R165 is connected to pin 2 of the common-mode inductor T4, and pin 4 is connected to pin 1 of the common-mode inductor T4.

[0006] Furthermore, the RS485 chip peripheral circuit module includes: The RS485 chip U24, whose pin 1 is connected to the pin 9 of the digital isolation chip U22 and one end of the resistor R162, and the other end of R162 is connected to VCC_ISO1; Resistor R38 and diode D63 are connected to one end of capacitor C595, and the other end of C595 is connected to GND_ISO1; Inverter U78, its pin 2 is connected to the other end of resistor R38, pin 3 is grounded, pin 5 is connected to VCC_ISO1, pin 4 is connected to pins 2 and 3 of RS485 chip U24, one end of resistor R163 and one end of capacitor C596, the other end of R163 is connected to VCC_ISO1, and the other end of C596 is connected to GND_ISO1.

[0007] Furthermore, the signal isolation circuit module includes: Pin 2 of the MCU is connected to one end of the pull-up resistor R151 and pin 2 of the isolation chip U22, and the other end of R151 is connected to VCC; Pin 3 of the MCU is connected to one end of the pull-up resistor R155 and pin 3 of the digital isolation chip U22, and the other end of R155 is connected to VCC; Pin 1 of the digital isolation chip U22 is connected to VCC, pin 5 is grounded, pin 10 is connected to VCC_ISO1, and pin 6 is connected to GND_ISO1; Common-mode inductor T24, pin 2 of which is connected to one end of capacitor C676, the other end of C676 and pin 1 of T24 are connected to GND, pin 3 of T24 is connected to one end of capacitor C162 and pin 2 of isolated power supply U23, the other end of C162 and pin 1 of U23 are connected to GND.

[0008] Furthermore, the external port module includes: The external terminal J31 has its pin 2 connected to the magnetic bead FB88, and its pin 1 connected to the magnetic bead FB89.

[0009] Furthermore, the RS485 protection circuit module also includes: One end of the air discharge tube GDT50 is connected to PGND_ISO1, and the other end is connected to PE; one end of the capacitor C657 is connected to PGND_ISO1, and the other end is connected to PE, wherein PE refers to the ground.

[0010] Furthermore, the RS485 chip peripheral circuit module also includes: Capacitor C167, one end of which is connected to VCC_ISO1, and the other end of which is connected to GND_ISO1.

[0011] Furthermore, the isolation circuit part also includes: Resistor R160 and capacitor C164 are connected to pin 4 of the isolated power supply U23, and pin 3 of U23 and the other end of C164 are connected to GND_ISO1.

[0012] Furthermore, the MCU module controls the optocoupler relay through the 120R_SEL signal to achieve remote control of the access of the 120R termination resistor.

[0013] Furthermore, the switch U1 controls whether the X_A ​​and X_B signals are connected to the current limiting resistors R772 and R773 through the R_SEL+ signal, thereby realizing remote control switching of the current limiting resistors.

[0014] According to the above-mentioned embodiments of the present invention, at least the following beneficial effects are achieved: the present invention can realize the access of the remote control circuit resistor by integrating the MCU module, the signal isolation circuit module, the RS485 chip peripheral circuit module, the RS485 protection circuit module and the external port module, thereby improving the flexibility and controllability of the circuit. The MCU module controls the working state of the entire circuit, thereby ensuring the stability and reliability of the circuit. The signal isolation circuit module effectively isolates the signal between the MCU module and the RS485 chip peripheral circuit module, thereby reducing signal interference and enhancing the anti-interference ability of the circuit. The RS485 protection circuit module protects the RS485 signal line from interference such as static electricity and surge, thereby improving the safety and stability of the circuit. The external port module is connected to the external RS485 communication network, thereby enabling the circuit to flexibly communicate with external devices, thereby expanding the scope of application of the circuit.

[0015] In addition, the RS485 protection circuit module of the present invention includes components such as switching switch, common mode inductor, digital isolation chip, magnetic beads and optical coupler relay, and these designs can effectively protect RS485 signal line, reduce the impact of external interference on circuit. Optical coupler relay is controlled by MCU module, and the access of remote control 120R termination resistor can be realized, and the static electricity problem that manual operation may introduce is avoided, and the convenience and safety of operation are improved. Meanwhile, the switching switch controls whether X_A and X_B signals access current limiting resistor by R_SEL+ signal, and the remote control switching of current limiting resistor is realized, and it can be flexibly adjusted according to the actual working state of the circuit, and the performance of the circuit is optimized, and the stability and communication quality of signal transmission are ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood by reading the detailed description below with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, in which: Figure 1 A schematic diagram of a high-protection RS485 circuit capable of remotely controlling circuit resistance access provided by an embodiment of the present invention; Figure 2 A schematic diagram of the structure of an RS485 protection circuit module circuit provided by an embodiment of the present invention; Figure 3 A schematic diagram of the structure of an RS485 chip peripheral circuit module provided by an embodiment of the present invention; Figure 4 A schematic diagram of the structure of a signal isolation circuit module provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0017] The principles and spirit of the present invention will be described below with reference to several exemplary embodiments. It should be understood that these embodiments are provided only to enable those skilled in the art to better understand and implement the present invention, and are not intended to limit the scope of the present invention in any way. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0018] Those skilled in the art know that the embodiments of the present invention can be implemented as a system, device, apparatus, method or computer program product. Therefore, the present invention can be specifically implemented in the following forms, namely: complete hardware, complete software (including firmware, resident software, microcode, etc.), or a combination of hardware and software.

[0019] It should be noted that any number of elements in the drawings is for illustration rather than limitation, and any naming is only for distinction and does not have any limiting meaning.

[0020] Reference below Figure 1 , Figure 1 This is a schematic diagram of a high-protection RS485 circuit that can be remotely controlled with a resistor connected to the circuit according to an embodiment of the present invention. Figure 1 As shown, a high protection performance RS485 circuit capable of remotely controlling circuit resistance access includes: The MCU module is used to control the working state of the entire circuit, and its output is connected to the input end of the signal isolation circuit module, and the input end receives the output signal from the signal isolation circuit module; The power module provides a stable power supply for the entire circuit, and its output end is respectively connected to the power input end of the MCU module, the signal isolation circuit module, the RS485 chip peripheral circuit module, the RS485 protection circuit module and the external port module; A signal isolation circuit module is used to isolate the signal between the MCU module and the RS485 chip peripheral circuit module, wherein the input end is connected to the output end of the MCU module, and the output end is connected to the input end of the RS485 chip peripheral circuit module; The RS485 chip peripheral circuit module is used to realize the transmission and reception of RS485 signals, and its input end is connected to the output end of the signal isolation circuit module, and the output end is connected to the input end of the RS485 protection circuit module; RS485 protection circuit module, used to protect RS485 signal line from static electricity, surge and other interference, its input end is connected to the output end of RS485 chip peripheral circuit module, and its output end is connected to the input end of external port module; The external port module is used to connect to an external RS485 communication network, with its input end connected to the output end of the RS485 protection circuit module, and its output end connected to the external RS485 communication network.

[0021] It should be noted that this embodiment describes a high protection performance RS485 circuit that can be remotely controlled to access the circuit resistor, and the circuit includes an MCU module, a power module, a signal isolation circuit module, an RS485 chip peripheral circuit module, an RS485 protection circuit module, and an external port module. The MCU module is the abbreviation of a micro control unit, which is responsible for controlling the working state of the entire circuit, and the signal isolation circuit module is used to isolate the signal between the MCU module and the RS485 chip peripheral circuit module to improve the anti-interference ability of the circuit.

[0022] Specifically, the MCU module is connected to the input end of the signal isolation circuit module through its output end, and the output end of the signal isolation circuit module is connected to the input end of the RS485 chip peripheral circuit module. The power supply module provides a stable power supply for the entire circuit, and its output end is connected to the power input end of each of the above modules.

[0023] More specifically, the RS485 chip peripheral circuit module is responsible for transmitting and receiving RS485 signals, and its output end is connected to the input end of the RS485 protection circuit module. The RS485 protection circuit module is used to protect the RS485 signal line from interference such as static electricity and surges, and its output end is connected to the input end of the external port module, while the external port module is used to connect to an external RS485 communication network, and its output end is connected to the external RS485 communication network.

[0024] Preferably, the MCU module can remotely control the optocoupler relay through a specific control signal to achieve remote control of the access to the 120R termination resistor. This design allows the access to the termination resistor to be controlled by software or remote instructions without direct contact with the circuit, thereby improving the flexibility and safety of the circuit.

[0025] Furthermore, the switch in the RS485 protection circuit module can control whether the X_A ​​and X_B signals are connected to the current limiting resistors R772 and R773 through the R_SEL+ signal, thereby realizing remote control switching of the current limiting resistors. This design can flexibly adjust the connection of the current limiting resistors according to the actual working state of the circuit, optimize the performance of the circuit, and ensure the stability of signal transmission and communication quality.

[0026] like Figure 2As shown, in some embodiments, a high protection performance RS485 circuit capable of remotely controlling circuit resistance access, the RS485 protection circuit module includes: Switch U1, with its pin 1 connected to pin 6 of RS485 chip U24, and its pin 2 connected to pin 7 of U24; Common mode inductor T4, pin 2 thereof is connected to one end of resistor R773, the other end of R773 is connected to pin 4 of switch U1, pin 1 of T4 is connected to one end of resistor R772, the other end of R772 is connected to pin 5 of switch U1; The digital isolation chip U22, whose pin 7 is connected to the pin 3 of the switch U1; Magnetic beads FB88 and FB89 are connected to pins 2 and 1 of external terminal J31 respectively; The optocoupler relay has its pin 1 connected to pin 1 of the MCU, pin 2 is grounded, pin 3 is connected to one end of resistor R165, the other end of R165 is connected to pin 2 of the common-mode inductor T4, and pin 4 is connected to pin 1 of the common-mode inductor T4.

[0027] It should be noted that this embodiment describes in detail the specific composition of the RS485 protection circuit module, which includes a switching switch U1, a common mode inductor T4, a digital isolation chip U2, magnetic beads FB88 and FB89, and an optocoupler relay. These components work together to protect the RS485 signal line from interference such as static electricity and surges. Among them, the switching switch U1 is an electronic switch used to control the selection of the signal path; the common mode inductor T4 is used to suppress common mode noise; the digital isolation chip U2 is used to isolate digital signals and improve the safety of the circuit; the magnetic beads FB88 and FB89 are used to suppress high-frequency noise; and the optocoupler relay controls the transmission of signals through photoelectric isolation.

[0028] Specifically, pin 1 of the switch U1 in the RS485 protection circuit module is connected to pin 6 of the RS485 chip U24, and pin 2 is connected to pin 7 of U24; pin 2 of the common mode inductor T4 is connected to one end of the resistor R773, the other end of R773 is connected to pin 3 of T4, pin 4 of T4 is connected to one end of the resistor R772, and the other end of R772 is connected to pin 1 of T4; pin 7 of the digital isolation chip U2 is connected to pin 3 of the switch U1; magnetic beads FB88 and FB89 are connected to pins 2 and 1 of the external terminal J31 respectively; pin 1 of the optocoupler relay is connected to pin 1 of the MCU, pin 2 is grounded, pin 3 is connected to one end of the resistor R165, the other end of R165 is connected to pin 2 of the common mode inductor T4, and pin 4 is connected to pin 1 of the common mode inductor T4. These connections ensure the stability and security of the signal during transmission, while providing effective protection against external interference.

[0029] Preferably, the design of the RS485 protection circuit module can be further refined. For example, the selection of the common-mode inductor T4 can be determined according to the operating frequency of the circuit and the noise frequency to be suppressed to ensure the best noise suppression effect. The digital isolation chip U2 can be selected according to its isolation voltage level and data transmission rate to meet the isolation and communication requirements of the circuit. The material and size of the magnetic beads FB88 and FB89 can be selected according to their noise suppression characteristics to maximize their suppression effect on high-frequency noise. The selection of the optocoupler relay can consider its isolation voltage level and response speed to ensure the reliability and rapidity of signal transmission.

[0030] Furthermore, other types of protection components, such as transient voltage suppressor diodes (TVS) or gas discharge tubes (GDTs), can also be considered as additional protection measures to further improve the protection capabilities of the circuit.

[0031] like Figure 3 As shown, in some embodiments, a high protection performance RS485 circuit capable of remotely controlling circuit resistance access, the RS485 chip peripheral circuit module includes: The RS485 chip U24, whose pin 1 is connected to the pin 9 of the digital isolation chip U22 and one end of the resistor R162, and the other end of R162 is connected to VCC_ISO1; Resistor R38 and diode D63 are connected to one end of capacitor C595, and the other end of C595 is connected to GND_ISO1; Inverter U78, its pin 2 is connected to the other end of resistor R38, pin 3 is grounded, pin 5 is connected to VCC_ISO1, pin 4 is connected to pins 2 and 3 of RS485 chip U24, one end of resistor R163 and one end of capacitor C596, the other end of R163 is connected to VCC_ISO1, and the other end of C596 is connected to GND_ISO1.

[0032] It should be noted that the present embodiment has elaborated the composition and function of RS485 chip peripheral circuit module, and this module includes RS485 chip U24, digital isolation chip U22, resistor R162, R163, R164, R165, R38, diode D63, capacitor C595, C596, C167 and inverter U78. These components work together to realize the sending and receiving of RS485 signal, and ensure the stability of signal and the safety of circuit. Among them, RS485 chip is the core component realizing serial communication, digital isolation chip is used to isolate digital signal to improve safety, resistor and capacitor are used for matching and filtering of signal, and inverter is used for logical inversion of signal.

[0033] Specifically, pin 1 of RS485 chip U24 is connected to pin 9 of digital isolation chip U22 and one end of resistor R162, and the other end of R162 is connected to VCC_ISO1; resistor R38 and diode D63 are connected to one end of capacitor C595, and the other end of C595 is connected to GND_ISO1; pin 2 of inverter U78 is connected to the other end of resistor R38, pin 3 is grounded, pin 5 is connected to VCC_ISO1, and pin 4 is connected to pins 2 and 3 of RS485 chip U24, one end of resistor R163 and one end of capacitor C596, the other end of R163 is connected to VCC_ISO1, and the other end of C596 is connected to GND_ISO1. These connections ensure that the RS485 chip can correctly receive and send signals, and at the same time improve the integrity of the signal and the anti-interference ability of the circuit through isolation and matching circuits.

[0034] Preferably, the design of the RS485 chip peripheral circuit module can be optimized according to specific application requirements. For example, the values ​​of resistors R162, R163, R164, and R165 can be adjusted according to the strength of the signal and the transmission distance to achieve the best signal matching. The values ​​of capacitors C595, C596, and C167 can be selected according to the noise frequency to be filtered out to ensure the clarity of the signal. Inverter U78 can be selected according to the signal type and logic requirements to be processed to ensure the correct processing of the signal.

[0035] Furthermore, you can also consider adding more protection components, such as transient voltage suppressor diodes (TVS) or gas discharge tubes (GDT) to further improve the protection capabilities of the circuit. These components can be connected in parallel on the signal line to protect the circuit from electrostatic discharge or voltage surges.

[0036] like Figure 4 As shown, in some embodiments, a high protection performance RS485 circuit capable of remotely controlling circuit resistance access, the signal isolation circuit module includes: Pin 2 of the MCU is connected to one end of the pull-up resistor R151 and pin 2 of the isolation chip U22, and the other end of R151 is connected to VCC; Pin 3 of the MCU is connected to one end of the pull-up resistor R155 and pin 3 of the digital isolation chip U22, and the other end of R155 is connected to VCC; Pin 1 of the digital isolation chip U22 is connected to VCC, pin 5 is grounded, pin 10 is connected to VCC_ISO1, and pin 6 is connected to GND_ISO1; Common-mode inductor T24, pin 2 of which is connected to one end of capacitor C676, the other end of C676 and pin 1 of T24 are connected to GND, pin 3 of T24 is connected to one end of capacitor C162 and pin 2 of isolated power supply U23, the other end of C162 and pin 1 of U23 are connected to GND.

[0037] It should be noted that this embodiment describes the specific composition and function of the signal isolation circuit module, which includes the pins of the MCU, pull-up resistors R151 and R155, the digital isolation chip U22, and the common mode inductor T24. The function of the signal isolation circuit module is to isolate the signal between the MCU module and the RS485 chip peripheral circuit module to improve the anti-interference ability of the circuit. The MCU (microcontroller unit) is the core component that controls the working state of the entire circuit, and the digital isolation chip U22 is used to isolate digital signals to prevent interference between circuits.

[0038] Specifically, pin 2 of the MCU is connected to one end of the pull-up resistor R151 and pin 2 of the isolation chip U22, and the other end of R151 is connected to VCC; pin 3 of the MCU is connected to one end of the pull-up resistor R155 and pin 3 of the digital isolation chip U22, and the other end of R155 is connected to VCC; pin 1 of the digital isolation chip U22 is connected to VCC, pin 5 is grounded, pin 10 is connected to VCC_ISO1, and pin 6 is connected to GND_ISO1; pin 2 of the common mode inductor T24 is connected to one end of the capacitor C676, and the other end of C676 and pin 1 of T24 are connected to GND, pin 3 of T24 is connected to one end of the capacitor C162 and pin 2 of the isolation power supply U23, and the other end of C162 and pin 1 of U23 are connected to GND. These connections ensure that the signal can be effectively transmitted while being isolated, and provide effective protection against external interference.

[0039] Preferably, the design of the signal isolation circuit module can be optimized according to specific application requirements. For example, the values ​​of the pull-up resistors R151 and R155 can be adjusted according to the input / output characteristics of the MCU and the signal transmission distance to ensure the stability and reliability of the signal. The selection of the digital isolation chip U22 can be determined according to its isolation voltage level and data transmission rate to meet the isolation and communication requirements of the circuit. The selection of the common-mode inductor T24 can be selected according to its characteristics of suppressing common-mode noise to maximize its suppression effect on common-mode interference.

[0040] Further, other types of isolation technologies, such as optical isolation or magnetic isolation, can also be considered as alternatives to further improve the isolation effect and anti-interference ability of the circuit. The values ​​of capacitors C676 and C162 can be selected according to the noise frequency that needs to be filtered out to ensure signal clarity and circuit stability.

[0041] In some embodiments, the external port module includes: The external terminal J31 has its pin 2 connected to the magnetic bead FB88, and its pin 1 connected to the magnetic bead FB89.

[0042] It should be noted that this embodiment describes the specific composition of the external port module, which includes an external terminal J31 and magnetic beads FB88 and FB89 connected thereto. The function of the external port module is to connect to an external RS485 communication network and provide a communication interface between the circuit and external devices. The external terminal J31 is an interface on the circuit board for connecting an external cable, while the magnetic beads FB88 and FB89 are used to suppress high-frequency noise and protect the circuit from electromagnetic interference.

[0043] Specifically, pin 2 of the external terminal J31 is connected to the magnetic bead FB88, and pin 1 is connected to the magnetic bead FB89. The magnetic beads here are electronic components made of ferrite materials, which are mainly used to suppress unwanted high-frequency signals. They reduce interference on the signal line by absorbing or reflecting high-frequency noise. As a bridge between the circuit and the external communication network, the design of the external terminal J31 needs to take into account factors such as mechanical strength, electrical performance, and environmental adaptability. The specific parameter settings of the magnetic beads FB88 and FB89, such as the DC resistance and magnetic permeability of the magnetic beads, will be determined according to the operating frequency of the circuit and the noise frequency that needs to be suppressed.

[0044] Preferably, the design of the external port module can be refined according to the specific application environment and protection requirements. For example, the external terminal J31 can be designed with a higher protection level, such as IP67 level, to prevent the intrusion of dust and water. The selection of magnetic beads FB88 and FB89 can consider their operating temperature range and maximum current carrying capacity to ensure normal operation even in extreme environments.

[0045] Further, you can consider adding additional protection components, such as transient voltage suppression diodes (TVS) or gas discharge tubes (GDT) to provide a higher level of surge protection. These components can be connected in parallel on the signal line to protect the circuit from electrostatic discharge or voltage surges. When designing, you can also consider using shielded cables and shielded interfaces to further reduce the impact of external electromagnetic interference on the circuit.

[0046] In some embodiments, the RS485 protection circuit module further includes: One end of the air discharge tube GDT50 is connected to PGND_ISO1, and the other end is connected to PE; one end of the capacitor C657 is connected to PGND_ISO1, and the other end is connected to PE, wherein PE refers to the ground.

[0047] It should be noted that this implementation describes in detail the configuration of the newly added air discharge tube GDT50 and capacitor C657 in the RS485 protection circuit module. These components are used to enhance the safety performance and anti-interference ability of the circuit. The air discharge tube (GDT) is a device that protects the circuit from high-energy transient voltage shocks, while the capacitor C657 is used to smooth voltage fluctuations. PGND_ISO1 refers to the isolation ground or protection ground, which is a point in the circuit for safe grounding.

[0048] Specifically, one end of the air discharge tube GDT50 is connected to PGND_ISO1, and the other end is connected to PE. One end of the capacitor C657 is connected to PGND_ISO1, and the other end is connected to PE (protective ground). Here, PGND_ISO1 is the ground wire of the isolation circuit, which is used to ensure that the safety requirements of the circuit are met. PE is the protective ground, which is used to connect the protection elements in the circuit to ensure that the current can be safely conducted in the event of a fault. The specific parameters of the air discharge tube GDT50, such as its breakdown voltage and pulse current tolerance, need to be set according to the operating voltage of the circuit and the expected surge current. The value of capacitor C657 needs to be determined based on its role in smoothing voltage fluctuations in the circuit.

[0049] Preferably, the design of the RS485 protection circuit module can be further refined. For example, the selection of the air discharge tube GDT50 can take into account its response time to ensure that it can be quickly turned on when a surge occurs, thereby protecting the circuit. The withstand voltage and capacity of the capacitor C657 need to be selected according to the operating voltage and current of the circuit to ensure that it will not be damaged when absorbing transient energy.

[0050] Furthermore, other types of protection components, such as metal oxide varistors (MOVs) or transient voltage suppressor diodes (TVSs), can be considered as a supplement or alternative to the air discharge tube GDT50 to provide more comprehensive protection. These components can be connected in parallel in the circuit to ensure effective protection at different levels of surge voltage. When designing, you can also consider adding a fuse or circuit breaker to cut off the power supply in extreme cases to further protect the circuit.

[0051] In some embodiments, the RS485 chip peripheral circuit module further includes: Capacitor C167, one end of which is connected to VCC_ISO1, and the other end of which is connected to GND_ISO1.

[0052] It should be noted that this embodiment describes the configuration of the newly added capacitor C167 in the RS485 chip peripheral circuit module, which is used to improve the power supply stability and anti-interference ability of the circuit. Capacitor C167 is an electronic component that can store and release electrical energy, which helps to filter out high-frequency noise and transient voltage fluctuations on the power line. VCC_ISO1 refers to the positive voltage terminal of the isolated power supply and is a key node in the circuit that provides power.

[0053] Specifically, one end of capacitor C167 is connected to VCC_ISO1, and the other end is connected to GND_ISO1. Here, VCC_ISO1 is the positive voltage terminal of the isolated power supply, and GND_ISO1 is the ground line of the isolated power supply. This connection method constitutes a power decoupling network, which helps to stabilize the power supply voltage and reduce noise on the power supply line.

[0054] More specifically, the parameters of capacitor C167, such as capacitance and withstand voltage, need to be set according to the operating frequency of the circuit and the power supply stability requirements. Usually, the selection of the capacitance value will take into account its effect in power supply filtering and decoupling, while the withstand voltage needs to be higher than the maximum operating voltage of the circuit to ensure that the capacitor will not be damaged under normal operating conditions.

[0055] Preferably, the design of the RS485 chip peripheral circuit module can be further refined. For example, the capacitance value of capacitor C167 can be selected to be at the μF (microfarad) level to provide sufficient energy storage capacity to cope with transient load changes. The withstand voltage value can be selected to be 16V or 25V, depending on the maximum voltage of VCC_ISO1.

[0056] Furthermore, different types of capacitors can be considered, such as ceramic capacitors or electrolytic capacitors, based on their characteristics in terms of temperature stability, volume, and cost. Ceramic capacitors generally have better temperature stability and high-frequency characteristics, while electrolytic capacitors offer larger capacitance values ​​and lower costs. When designing, you can also consider adding multiple capacitors with different capacitance values ​​in parallel to achieve a wider bandwidth noise suppression effect.

[0057] In some embodiments, the isolation circuit portion further includes: Resistor R160 and capacitor C164 are connected to pin 4 of the isolated power supply U23, and pin 3 of U23 and the other end of C164 are connected to GND_ISO1.

[0058] It should be noted that this embodiment describes the composition of the isolation circuit part, which includes a resistor R160 and a capacitor C164, which are connected to pin 4 of the isolation power supply U23, and pin 3 of U23 and the other end of C164 are connected to GND_ISO1. The isolation power supply U23 is a circuit component used to provide electrical isolation between different circuit parts to enhance safety and anti-interference capabilities. GND_ISO1 is the ground wire of the isolation circuit, which is used to ensure the grounding safety of the circuit.

[0059] Specifically, the connection method of resistor R160 and capacitor C164 is to provide a stable electrical connection between the input of the isolated power supply U23 and the ground, while reducing noise and interference. Resistor R160 plays a current limiting role to protect the back-end circuit from being damaged by excessive current; capacitor C164 is used to filter out high-frequency noise that may be conducted through the power line.

[0060] More specifically, the parameters of these components, such as resistance and capacitance values, need to be set according to the operating voltage, current and anti-interference requirements of the isolated power supply. Typically, the value of resistor R160 is determined according to the input current and safety standards of the circuit, while the value of capacitor C164 needs to be selected according to its effect in filtering and decoupling.

[0061] Preferably, the design of the isolation circuit part can be further refined. For example, the resistor R160 can be selected to have an appropriate value to ensure that the performance of the circuit is not affected under normal working conditions, while being able to limit excessive current under abnormal conditions. The capacitance value of the capacitor C164 can be selected to be at the nF (nanofarad) level to provide sufficient energy storage capacity to cope with transient load changes.

[0062] Further, different types of capacitors can be considered, such as ceramic capacitors or film capacitors, selected based on their characteristics in terms of temperature stability, volume, and cost. Ceramic capacitors generally have better temperature stability and high-frequency characteristics, while film capacitors offer larger capacitance values ​​and lower equivalent series resistance (ESR).

[0063] Furthermore, when designing, it is also possible to consider adding multiple capacitors with different capacitance values ​​in parallel to achieve a wider bandwidth noise suppression effect. At the same time, it is also possible to consider adding a fuse or circuit breaker to cut off the power supply in extreme cases to further protect the circuit.

[0064] In some embodiments, the MCU module controls the optocoupler relay through the 120R_SEL signal to achieve remote control of the access of the 120R termination resistor.

[0065] It should be noted that this embodiment describes that the MCU module controls the optocoupler relay through the 120R_SEL signal to achieve remote control of the access of the 120R termination resistor. The optocoupler relay is a device that uses the photoelectric effect to achieve signal isolation. It can electrically isolate the control end and the controlled end, thereby improving the safety and anti-interference ability of the system. The 120R termination resistor refers to a 120 ohm resistor connected at the end of the RS485 communication line to reduce signal reflection and improve signal quality.

[0066] Specifically, the 120R_SEL signal output by the MCU module is used to control the state of the optocoupler relay. The on and off states of the optocoupler relay determine whether the 120R termination resistor is connected to the circuit. When the 120R_SEL signal activates the optocoupler relay, the output end of the optocoupler relay is turned on, so that the 120R termination resistor is connected to the RS485 line; conversely, when the 120R_SEL signal does not activate the optocoupler relay, the output end of the optocoupler relay is cut off and the 120R termination resistor is disconnected. This control method can realize remote control of the termination resistor without physical contact with the circuit, which improves the convenience and safety of operation. The specific parameter settings of the MCU module, such as the level output capability of the I / O port, need to match the input characteristics of the optocoupler relay.

[0067] Preferably, the interface design between the MCU module and the optocoupler relay can be further refined. For example, the I / O port of the MCU module can be configured as push-pull output or open-drain output to adapt to different optocoupler relay input requirements. Push-pull output can provide stronger driving capability, while open-drain output requires an external pull-up resistor. The selection of optocoupler relays can consider their isolation voltage level, response speed, and maximum current carrying capacity to ensure stable operation under various working conditions.

[0068] Furthermore, a current limiting resistor can be added between the MCU module and the optocoupler relay to protect the MCU's I / O port from damage by excessive current. The value of the current limiting resistor can be determined based on the maximum output current of the MCU's I / O port and the minimum input current requirement of the optocoupler relay.

[0069] Furthermore, during design, one can also consider using software programming to achieve precise control of the 120R_SEL signal, such as adjusting the on-time of the optocoupler relay through a PWM (pulse width modulation) signal to achieve finer control.

[0070] In some embodiments, the switch U1 controls whether the X_A ​​and X_B signals are connected to the current limiting resistors R772 and R773 through the R_SEL+ signal, thereby realizing remote control switching of the current limiting resistors.

[0071] It should be noted that this embodiment describes that the switching switch U1 controls whether the X_A ​​and X_B signals are connected to the current limiting resistors R772 and R773 through the R_SEL+ signal to achieve remote control switching of the current limiting resistors. The switching switch U1 is an electronic switch used to switch the signal path in the circuit, and the current limiting resistors R772 and R773 are used to limit the current passing through the RS485 line to protect the circuit from damage caused by excessive current. The R_SEL+ signal is a control signal used to control the state of the switching switch U1.

[0072] Specifically, the control end of the switching switch U1 receives the R_SEL+ signal. When the R_SEL+ signal is at a high level, the switching switch U1 connects the X_A ​​and X_B signals to the current limiting resistors R772 and R773, thereby limiting the current passing through the RS485 line; when the R_SEL+ signal is at a low level, the switching switch U1 connects the X_A ​​and X_B signals directly to the RS485 line, bypassing the current limiting resistor. This design allows the current limiting resistor to be removed when the RS485 line sends data, increasing the driving capability, and adding the current limiting resistor when receiving data to absorb overvoltage energy and protect the circuit. The specific parameters of the current limiting resistors R772 and R773, such as the resistance value, need to be set according to the maximum allowable current of the RS485 line and the protection requirements of the circuit.

[0073] Preferably, the operation steps of the switching switch U1 and the current limiting resistors R772 and R773 can be further refined. For example, the switching switch U1 can be selected as an analog switch or a digital switch, which is determined according to the type and speed of the signal it can process. The analog switch is suitable for switching analog signals, while the digital switch is suitable for switching digital signals. The resistance values ​​of the current limiting resistors R772 and R773 can be selected according to the maximum data transmission rate of the RS485 line and the protection level of the circuit to ensure that sufficient protection is provided without affecting the signal transmission quality.

[0074] Furthermore, it is possible to consider adding a buffer or driver between the switch U1 and the current limiting resistor to improve the signal driving capability, especially in the case of long-distance transmission or multi-device connection. The selection of the buffer or driver should consider its input and output level compatibility, as well as the current driving capability it can provide.

[0075] Furthermore, during design, it is also possible to consider using software programming to achieve precise control of the R_SEL+ signal, such as optimizing the signal transmission and reception process by setting different levels or time delays.

[0076] The above-mentioned various embodiments of the present invention have the following beneficial effects: the RS485 circuit with high protection performance described in the present invention is designed to allow the access of the remote control circuit resistor, thereby improving the flexibility and adaptability of the circuit. The circuit includes an MCU module, a power module, a signal isolation circuit module, an RS485 chip peripheral circuit module, an RS485 protection circuit module and an external port module, and the integration of these modules can ensure the stability and reliability of the circuit under various working conditions. The control function of the MCU module, the isolation effect of the signal isolation circuit module, the signal transceiver capability of the RS485 chip peripheral circuit module, the protection mechanism of the RS485 protection circuit module and the external communication connection capability of the external port module jointly improve the anti-interference and protection level of the circuit, so that it can adapt to various complex industrial environments and the requirements of the power industry.

[0077] In addition, the RS485 protection circuit module includes the configuration of switching switches, common-mode inductors, digital isolation chips, magnetic beads, optocoupler relays and other components. These designs can effectively protect the RS485 signal line from interference such as static electricity and surges. In particular, the MCU module controls the optocoupler relay to achieve remote control access to the 120R termination resistor, and the switching switch controls whether the X_A ​​and X_B signals are connected to the current limiting resistor through the R_SEL+ signal, realizing remote control switching of the current limiting resistor. These functions can optimize the performance of the circuit, ensure the stability of signal transmission and communication quality, and also reduce the need for manual operation and reduce the risk of circuit damage caused by improper operation.

[0078] Furthermore, the storage medium of the embodiment of the present application stores program instructions that can implement all the above methods, wherein the program instructions can be stored in the above storage medium in the form of a software product, including several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) or a processor to execute all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, or terminal devices such as a computer, a server, a mobile phone, and a tablet.

[0079] The above descriptions are only some preferred embodiments of the present invention and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present invention is not limited to the technical solutions formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the embodiments of the present invention.

Claims

1. A high protection performance RS485 circuit capable of remotely controlling circuit resistance access, characterized in that: include: The MCU module is used to control the working state of the entire circuit, and its output is connected to the input end of the signal isolation circuit module, and the input end receives the output signal from the signal isolation circuit module; The power module provides a stable power supply for the entire circuit, and its output end is respectively connected to the power input end of the MCU module, the signal isolation circuit module, the RS485 chip peripheral circuit module, the RS485 protection circuit module and the external port module; A signal isolation circuit module is used to isolate the signal between the MCU module and the RS485 chip peripheral circuit module, wherein the input end is connected to the output end of the MCU module, and the output end is connected to the input end of the RS485 chip peripheral circuit module; The RS485 chip peripheral circuit module is used to realize the transmission and reception of RS485 signals, and its input end is connected to the output end of the signal isolation circuit module, and the output end is connected to the input end of the RS485 protection circuit module; RS485 protection circuit module, used to protect RS485 signal line from static electricity, surge and other interference, its input end is connected to the output end of RS485 chip peripheral circuit module, and its output end is connected to the input end of external port module; An external port module is used to connect to an external RS485 communication network, an input end of which is connected to an output end of the RS485 protection circuit module, and an output end of which is connected to the external RS485 communication network; The MCU module controls the optocoupler relay through the SEL signal to achieve remote control of the access of the 120R terminal resistor. When the SEL signal activates the optocoupler relay, the output end of the optocoupler relay is turned on, so that the 120R terminal resistor is connected to the RS485 line; On the contrary, when the SEL signal does not activate the optocoupler relay, the output end of the optocoupler relay is cut off and the 120R terminating resistor is disconnected.

2. A high protection performance RS485 circuit capable of remotely controlling circuit resistance access according to claim 1, characterized in that: The RS485 protection circuit module includes: Switch U1, with its pin 1 connected to pin 6 of RS485 chip U24, and its pin 2 connected to pin 7 of U24; Common mode inductor T4, pin 2 thereof is connected to one end of resistor R773, the other end of R773 is connected to pin 4 of switch U1, pin 1 of T4 is connected to one end of resistor R772, the other end of R772 is connected to pin 5 of switch U1; The digital isolation chip U22, whose pin 7 is connected to the pin 3 of the switch U1; Magnetic beads FB88 and FB89 are connected to pins 2 and 1 of external terminal J31 respectively; The optocoupler relay has its pin 1 connected to pin 1 of the MCU, pin 2 is grounded, pin 3 is connected to one end of resistor R165, the other end of R165 is connected to pin 2 of the common-mode inductor T4, and pin 4 is connected to pin 1 of the common-mode inductor T4.

3. A high protection performance RS485 circuit capable of remotely controlling circuit resistance access according to claim 1, characterized in that: The RS485 chip peripheral circuit module includes: The RS485 chip U24, whose pin 1 is connected to the pin 9 of the digital isolation chip U22 and one end of the resistor R162, and the other end of R162 is connected to VCC_ISO1; Resistor R38 and diode D63 are connected to one end of capacitor C595, and the other end of C595 is connected to GND_ISO1; Inverter U78, its pin 2 is connected to the other end of resistor R38, pin 3 is grounded, pin 5 is connected to VCC_ISO1, pin 4 is connected to pins 2 and 3 of RS485 chip U24, one end of resistor R163 and one end of capacitor C596, the other end of R163 is connected to VCC_ISO1, and the other end of C596 is connected to GND_ISO1.

4. A high protection performance RS485 circuit capable of remotely controlling circuit resistance access according to claim 1, characterized in that: The signal isolation circuit module comprises: Pin 2 of the MCU is connected to one end of the pull-up resistor R151 and pin 2 of the isolation chip U22, and the other end of R151 is connected to VCC; Pin 3 of the MCU is connected to one end of the pull-up resistor R155 and pin 3 of the digital isolation chip U22, and the other end of R155 is connected to VCC; Pin 1 of the digital isolation chip U22 is connected to VCC, pin 5 is grounded, pin 10 is connected to VCC_ISO1, and pin 6 is connected to GND_ISO1; Common-mode inductor T24, pin 2 of which is connected to one end of capacitor C676, the other end of C676 and pin 1 of T24 are connected to GND, pin 3 of T24 is connected to one end of capacitor C162 and pin 2 of isolated power supply U23, the other end of C162 and pin 1 of U23 are connected to GND.

5. A high protection performance RS485 circuit capable of remotely controlling circuit resistance access according to claim 1, characterized in that: The external port module comprises: The external terminal J31 has its pin 2 connected to the magnetic bead FB88, and its pin 1 connected to the magnetic bead FB89.

6. A high protection performance RS485 circuit capable of remotely controlling circuit resistance access according to claim 2, characterized in that: The RS485 protection circuit module also includes: One end of the air discharge tube GDT50 is connected to PGND_ISO1, and the other end is connected to PE; one end of the capacitor C657 is connected to PGND_ISO1, and the other end is connected to PE, wherein PE refers to the ground.

7. A high protection performance RS485 circuit capable of remotely controlling circuit resistance access according to claim 3, characterized in that: The RS485 chip peripheral circuit module also includes: Capacitor C167, one end of which is connected to VCC_ISO1, and the other end of which is connected to GND_ISO1.

8. A high protection performance RS485 circuit capable of remotely controlling circuit resistance access according to claim 4, characterized in that: The isolation circuit part also includes: Resistor R160 and capacitor C164 are connected to pin 4 of the isolated power supply U23, and pin 3 of U23 and the other end of C164 are connected to GND_ISO1.

9. A high protection performance RS485 circuit capable of remotely controlling circuit resistance access according to claim 1, characterized in that: The MCU module controls the optocoupler relay through the 120R_SEL signal to achieve remote control of the access of the 120R termination resistor.

10. The high protection performance RS485 circuit capable of remotely controlling circuit resistance access according to claim 1, characterized in that: The switch U1 controls whether the X_A ​​and X_B signals are connected to the current limiting resistors R772 and R773 through the R_SEL+ signal, thereby realizing remote control switching of the current limiting resistors.

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