Protection circuit, device and system for serial port communication

Abstract

The utility model relates to a protection circuit, device and system for serial port communication, belongs to the field of circuits, and aims to solve the problem that existing communication equipment is easy to damage when receiving surge-containing signals. The serial port communication protection circuit comprises an RS485 serial port, a serial port conversion chip, an anti-thunder surge circuit and a filter circuit, the anti-thunder surge circuit and the filter circuit are both located between the RS485 serial port and the serial port conversion chip and are connected in sequence, the anti-thunder surge circuit is provided with a TVS tube, the TVS tube is used for carrying out communication anti-thunder surge on the serial port conversion chip, one end of the filter circuit is grounded, and the other end of the filter circuit is grounded. And the other end of the filter circuit is connected with the RS485 serial port. The utility model further provides a serial port communication protection device and system. A TVS tube of the lightning surge protection circuit is used for carrying out lightning surge protection on communication of the serial port conversion chip, and a filter circuit is used for filtering, so that the risk of serial port communication damage is reduced, and the serial port communication quality is improved.

Description

Technical Field

[0001] The present application relates to the field of circuits, and in particular, to a protection circuit, device and system for serial communication. Background Art

[0002] When transmitting serial communication signals through a transmission line, if there is a magnetic field, lightning strike, etc. in the area where the transmission line is located, the serial communication signals transmitted through the transmission line are prone to carry surge current, high voltage or static electricity. Since the serial communication interface in the communication equipment is usually not equipped with a protection function, the communication equipment may fail when receiving serial communication signals carrying surge current, high voltage or static electricity. Utility Model Content

[0003] The purpose of the present application is to provide a serial communication protection circuit, device and system to solve the problem that communication equipment is easily damaged when receiving serial communication signals containing surge, high voltage and high current.

[0004] In order to solve the above problems, the present application adopts the following technical solutions:

[0005] A first aspect of the present application provides a protection circuit for serial port communication, comprising: an RS485 serial port, a serial port conversion chip, a lightning surge protection circuit and a filtering circuit, wherein the lightning surge protection circuit and the filtering circuit are both located between the RS485 serial port and the serial port conversion chip and are connected in sequence, wherein the lightning surge protection circuit is provided with a TVS tube, and the TVS tube is used to protect the serial port conversion chip communication from lightning surges, one end of the filtering circuit is grounded, and the other end of the filtering circuit is connected to the RS485 serial port.

[0006] The filter circuit can effectively remove electromagnetic interference in the communication line, ensure the correct transmission of data, reduce the bit error rate, and improve communication stability. The TVS tube in the lightning surge protection circuit can quickly respond to and absorb the overvoltage caused by lightning strikes or power grid surges, protecting the serial port conversion chip from damage. Since the lightning surge protection circuit and the filter circuit are connected in sequence between the RS485 serial port and the serial port conversion chip, the failure rate caused by external electromagnetic interference and voltage surges is effectively reduced.

[0007] Furthermore, two TVS tubes are provided in the lightning surge protection circuit, one TVS tube is used to perform line surge protection on the negative end of the RS485 serial port, and the other TVS tube is used to perform line surge protection on the positive end of the RS485 serial port, and the other ends of the two TVS tubes are grounded.

[0008] The two TVS tubes protect the positive and negative ends of the RS485 serial port respectively, which can effectively absorb the forward and reverse surge voltages in the line and respond to the surge voltage in the line more quickly, which helps to reduce equipment failures caused by surge voltage and improve the overall reliability of the equipment.

[0009] Further, the filter circuit includes two capacitors, one of which is used for anti-interference filtering of the negative end of the RS485 serial port, and the other capacitor is used for anti-interference filtering of the positive end of the RS485 serial port, and the other ends of the two capacitors are grounded. The two capacitors perform anti-interference filtering on the positive and negative ends of the RS485 serial port, respectively, effectively removing high-frequency noise and electromagnetic interference in the signal, improving the quality of the RS485 serial port signal, reducing the bit error rate caused by electromagnetic interference, and improving the accuracy of data transmission.

[0010] Furthermore, the serial communication protection circuit also includes a first impedance matching circuit, which is located between the serial port conversion chip and the RS485 serial port, and the serial port conversion chip, the first impedance matching circuit, the lightning surge protection circuit and the RS485 serial port are arranged in sequence.

[0011] Since the first impedance matching circuit is located between the serial port conversion chip and the RS485 serial port, it helps to enhance the transmission distance of the signal, so that the communication can maintain stability and reliability at a longer distance, ensure impedance matching of the signal during transmission, and reduce signal reflection and loss.

[0012] Furthermore, the first impedance matching circuit includes a first resistor, one end of the TVS tube is electrically connected to the first resistor, and the other end of the TVS tube is grounded. By setting the first resistor, the impedance between the serial port conversion chip and the RS485 serial port is matched, signal reflection and loss are reduced, the signal transmission distance is increased, the bit error caused by signal reflection is reduced, and the accuracy of data transmission is improved.

[0013] Furthermore, the serial port conversion chip is provided with a matching module, and the matching module is used to set different voltage signals for the pins of the serial port conversion chip to adapt to the conversion between different communication models.

[0014] Since the matching module can set different voltage signals for the pins of the serial port conversion chip to adapt to the conversion between different communication models, the circuit can be flexibly adapted to various communication models, thereby improving the compatibility of the circuit.

[0015] Furthermore, the serial communication protection circuit also includes a second impedance matching circuit, which is connected to the serial port conversion chip. The second impedance matching circuit optimizes signal quality, so that the matching module sets different voltage signals for the pins of the serial port conversion chip more stably.

[0016] Furthermore, the second impedance matching circuit includes two second resistors, one end of the two second resistors is electrically connected to the power supply, and the other end of the two second resistors is electrically connected to the two pins of the serial port conversion chip. Due to the second resistors, the second impedance matching circuit reduces signal reflection, optimizes signal quality, effectively protects the signal, and reduces signal loss.

[0017] A second aspect of the present application provides a serial communication protection device, comprising: a shell having a receiving cavity formed therein, and any one of the serial communication protection circuits described above, disposed in the shell.

[0018] A third aspect of the present application provides a serial communication protection system, and the serial communication protection system includes the above-mentioned device.

[0019] Compared with the prior art, the beneficial effect of the present application is that: since the lightning surge protection circuit and the filtering circuit are connected in sequence between the RS485 serial port and the serial port conversion chip, the filtering circuit removes electromagnetic interference in the communication line, and the TVS tube in the lightning surge protection circuit can absorb the overvoltage generated by lightning strikes or power grid surges, protecting the serial port conversion chip from damage, thereby reducing the risk of serial port communication damage and improving the quality of serial port communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A circuit diagram of a serial port conversion chip provided in an embodiment of the present application;

[0021] Figure 2 A structural block diagram of a serial communication protection circuit provided in an embodiment of the present application;

[0022] Figure 3 A circuit diagram of a first impedance matching circuit provided in an embodiment of the present application;

[0023] Figure 4 A circuit diagram of a lightning surge protection circuit provided in an embodiment of the present application;

[0024] Figure 5 A circuit diagram of a filter circuit provided in an embodiment of the present application; and

[0025] Figure 6 A circuit diagram of a second impedance matching circuit provided in an embodiment of the present application.

[0026] Description of reference numerals:

[0027] 1. RS484 serial port; 2. Serial port conversion chip; 3. Lightning surge protection circuit; 4. Filter circuit; 5. First impedance matching circuit; 6. Second impedance matching circuit; R10, first resistor; R11, second resistor; C1, first capacitor. DETAILED DESCRIPTION

[0028] The specific implementation methods of the present application are described in detail below with reference to the accompanying drawings.

[0029] It should be noted that, in the absence of conflict, the embodiments and technical features in the embodiments of the present application can be combined with each other, and the detailed description in the specific implementation method should be understood as an explanation of the purpose of the present application and should not be regarded as an improper limitation on the present application.

[0030] It should be understood that the orientation or position relationship is based on the orientation or position relationship shown in the drawings. These orientation terms are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application.

[0031] Figure 1 A circuit diagram of a serial port conversion chip provided in an embodiment of the present application, Figure 2 A structural block diagram of a serial communication protection circuit provided in an embodiment of the present application, Figure 3 A circuit diagram of a first impedance matching circuit provided in an embodiment of the present application, Figure 4 A circuit diagram of a lightning surge protection circuit provided in an embodiment of the present application, Figure 5 A circuit diagram of a filter circuit provided in an embodiment of the present application. Figure 1 to Figure 5 As shown, an embodiment of the present application provides a protection circuit for serial communication, including: an RS485 serial port 1, a serial port conversion chip 2, a lightning surge protection circuit 3 and a filter circuit 4, wherein the lightning surge protection circuit 3 and the filter circuit 4 are both located between the RS485 serial port 1 and the serial port conversion chip 2, and are connected in sequence, wherein the lightning surge protection circuit 3 is provided with a TVS tube, which is used to protect the serial port conversion chip 2 from lightning surges, one end of the filter circuit 4 is grounded, and the other end of the filter circuit 4 is connected to the RS485 serial port 1.

[0032] Specifically, the serial port conversion chip 2 is connected between the RS485 serial port 1 and the lightning surge protection circuit 3, and is used to convert serial signals into parallel signals for data transmission between multiple devices. The lightning surge protection circuit 3 is provided with a TVS tube, which is used to protect the serial port conversion chip 2 from lightning surges and protect the chip from damage caused by lightning breakdown and voltage surges. The filter circuit 4 filters out high-frequency noise and interference signals in the communication line to ensure the stability of signal transmission. One end of the filter circuit 4 is grounded to improve the safety of the circuit. The serial port conversion chip 2 is provided with pins DCD1_485- and pins RXD1_485+, and the RS485 serial port 1 corresponds to the connection pins DCD1_485- and pins RXD1_485+. The lightning surge protection circuit 3 is provided with DCD1_485-_R and RXD1_485+_R connection terminals, and the DCD1_485-_R and RXD1_485+_R connection terminals of the lightning surge protection circuit 3 correspond to the connection pins DCD1_485-_R and RXD1_485+_R connected to the RS485 serial port 1, respectively. Similarly, the DCD1_485-_R and RXD1_485+_R connection terminals of the filter circuit 4 correspond to the connection pins DCD1_485-_R and RXD1_485+_R connected to the RS485 serial port 1, respectively (see Figure 3-Figure 5 ).

[0033] When the serial communication signal is transmitted through the RS485 serial port 1, the signal first passes through the lightning protection surge circuit 3, and the TVS tube quickly clamps the signal to limit the voltage rise rate, protecting the serial port conversion chip 2 from lightning breakdown and voltage surge damage. After the signal is protected by the lightning protection surge circuit 3, it continues to be transmitted to the filter circuit 4, which filters the signal to filter out high-frequency noise and interference signals, and the filtered signal is transmitted to the serial port conversion chip 2. The serial port conversion chip 2 converts the serial signal into a parallel signal to facilitate data transmission between multiple devices. The signal processed by the serial port conversion chip 2 continues to be transmitted to the target device to complete the serial communication process.

[0034] The filter circuit can effectively remove electromagnetic interference in the communication line, ensure the correct transmission of data, reduce the bit error rate, and improve communication stability. The TVS tube in the lightning surge protection circuit can quickly respond to and absorb the overvoltage caused by lightning strikes or power grid surges, protecting the serial port conversion chip from damage. Since the lightning surge protection circuit and the filter circuit are connected in sequence between the RS485 serial port and the serial port conversion chip, the failure rate caused by external electromagnetic interference and voltage surges is effectively reduced.

[0035] In some embodiments, two TVS tubes are provided in the lightning surge protection circuit 3, one TVS tube is used to perform line surge protection on the negative end of the RS485 serial port 1, and the other TVS tube is used to perform line surge protection on the positive end of the RS485 serial port 1, and the other ends of the two TVS tubes are grounded.

[0036] Specifically, the RS485 serial port 1 is used for serial communication, and includes a positive terminal RXD1_485+_R and a negative terminal DCD1_485-_R, which are used to transmit differential signals. The lightning surge protection circuit 3 is provided with two TVS tubes, the first TVS tube is connected to the negative terminal DCD1_485-_R of the RS485 serial port 1, and is used to perform line surge protection on the negative terminal. The second TVS tube is connected to the positive terminal RXD1_485+_R of the RS485 serial port 1, and is used to perform line surge protection on the positive terminal, and the other ends of the two TVS tubes are grounded.

[0037] When the serial communication signal is transmitted through the RS485 serial port 1, the positive end RXD1_485+_R and the negative end DCD1_485-_R of the signal will pass through the TVS tube in the lightning surge protection circuit 3. When lightning breakdown or other voltage surges occur, the TVS tube at the negative end will quickly conduct and guide the overvoltage to the ground wire, thereby protecting the negative end of the RS485 serial port 1 from damage. At the same time, the TVS tube at the positive end will also conduct and guide the overvoltage to the ground wire, protecting the positive end RXD1_485+_R of the RS485 serial port 1 from damage. The signal protected by the two TVS tubes in the lightning surge protection circuit 3 continues to be transmitted to the serial port conversion chip 2. The two TVS tubes protect the positive and negative ends of the RS485 serial port respectively, which can effectively absorb the forward and reverse surge voltages in the line, respond to the surge voltage in the line more quickly, help reduce equipment failures caused by surge voltages, and improve the overall reliability of the equipment.

[0038] In some embodiments, the filter circuit 4 includes two capacitors C1, one capacitor C1 is used for anti-interference filtering of the negative end DCD1_485-_R of the RS485 serial port 1, and the other capacitor C1 is used for anti-interference filtering of the positive end of the RS485 serial port 1, and the other ends of the two capacitors C1 are grounded.

[0039] Specifically, the filter circuit 4 includes two capacitors C1, the first capacitor C1 is connected to the DCD1_485-_R of the RS485 serial port 1, and is used for anti-interference filtering of DCD1_485-_R. The second capacitor C1 is connected to the RXD1_485+_R of the RS485 serial port 1, and is used for anti-interference filtering of RXD1_485+_R. The other ends of the two capacitors C1 are grounded. The capacitor C1 performs anti-interference filtering on the signal, filters out high-frequency noise and interference signals, and ensures the stability and reliability of signal transmission, wherein the capacitor C1 at the negative end filters out interference affecting the negative end, and the capacitor C1 at the positive end filters out interference affecting the positive end, and the signal filtered by the two capacitors C1 in the filter circuit 4 continues to be transmitted to the serial port conversion chip 2.

[0040] The two capacitors perform anti-interference filtering on the positive and negative ends of the RS485 serial port respectively, effectively removing high-frequency noise and electromagnetic interference in the signal, improving the quality of the RS485 serial port signal, reducing the bit error rate caused by electromagnetic interference, and improving the accuracy of data transmission.

[0041] like Figure 3 As shown, in some embodiments, the protection circuit of the serial communication also includes a first impedance matching circuit 5, which is located between the serial port conversion chip 2 and the RS485 serial port 1, and the serial port conversion chip 2, the first impedance matching circuit 5, the lightning surge protection circuit 3 and the RS485 serial port 1 are arranged in sequence.

[0042] Specifically, the lightning surge protection circuit 3 is connected between the RS485 serial port 1 and the first impedance matching circuit 5, and is used to transmit data between multiple devices to improve the data transmission effect. The first impedance matching circuit 5 is located between the serial port conversion chip 2 and the RS485 serial port 1, and is used to match the impedance between the serial port conversion chip 2 and the RS485 serial port 1 to ensure the effective transmission of the signal and reduce signal reflection. When the serial port communication signal is transmitted through the serial port conversion chip 2, the signal passes through the first impedance matching circuit 5, and the first impedance matching circuit 5 ensures that the impedance of the signal matches the impedance of the RS485 serial port 1, thereby reducing signal reflection and loss. The signal processed by the first impedance matching circuit 5 continues to be transmitted to the lightning surge protection circuit 3. The lightning surge protection circuit 3 protects the signal to prevent lightning breakdown and voltage surges from damaging the RS485 serial port 1.

[0043] Since the first impedance matching circuit is located between the serial port conversion chip and the RS485 serial port, it helps to enhance the transmission distance of the signal, so that the communication can maintain stability and reliability at a longer distance, ensure impedance matching of the signal during transmission, and reduce signal reflection and loss.

[0044] In some embodiments, the first impedance matching circuit 5 includes a first resistor R10, one end of the TVS tube is electrically connected to the first resistor R10, and the other end of the TVS tube is grounded.

[0045] Specifically, the first impedance matching circuit 5 is located between the serial port conversion chip 2 and the RS485 serial port 1. The first resistor R10 of the first impedance matching circuit 5 is used to adjust the impedance of the circuit to match the impedance between the serial port conversion chip 2 and the RS485 serial port 1. One end of the TVS tube is electrically connected to the first resistor R10, and the other end of the TVS tube is grounded. When the serial communication signal is transmitted through the serial port conversion chip 2, the signal passes through the first resistor R10. The first resistor R10 performs impedance adjustment on the signal to ensure that the impedance of the signal matches the impedance of the RS485 serial port 1. One end of the TVS tube is electrically connected to the first resistor R10, and the other end is grounded. The TVS tube is quickly turned on when a voltage surge occurs, directing the overvoltage to the ground wire, protecting the circuit from damage caused by lightning breakdown and voltage surges, and the signal protected by the TVS tube continues to be transmitted to the target device.

[0046] By setting the first resistor R10, the impedance between the serial port conversion chip 2 and the RS485 serial port 1 is matched, signal reflection and loss are reduced, the signal transmission distance is increased, the bit error caused by signal reflection is reduced, and the accuracy of data transmission is improved.

[0047] In some embodiments, the serial port conversion chip 2 is provided with a matching module, and the matching module is used to set different voltage signals for the pins of the serial port conversion chip 1 to adapt to the conversion between different communication models.

[0048] Specifically, the matching module is used to set different voltage signals for the pins of the serial port conversion chip 2 to adapt to the conversion between different communication models so as to transmit data between multiple devices. When the serial port communication signal is transmitted through the RS485 serial port 1, the signal passes through the matching module, and the matching module sets different voltage signals for the pins of the serial port conversion chip 2 according to the requirements of different communication models. After the matching module adjusts the voltage signal, the serial signal is converted into a parallel signal so as to transmit data between multiple devices. The signal processed by the serial port conversion chip 2 continues to be transmitted to the target device to complete the serial port communication process.

[0049] Different values ​​are set for MODE_1, MODE_2, and SD through the pins of the serial port conversion chip 2 to achieve matching of different transmission modes. For example, when SD is 0, MODE_1 is 0, and MODE_2 is 0, the transmission mode is RS422 serial port signal transmission; when SD is 0, MODE_1 is 0, and MODE_2 is 1, the transmission mode is RS232 serial port signal transmission; when SD is 0 and MODE_1 is 1, the transmission mode is RS485 serial port signal transmission; when SD is 1, the transmission mode is Shutdown Mode.

[0050] Since the matching module can set different voltage signals for the pins of the serial port conversion chip to adapt to the conversion between different communication models, the circuit can be flexibly adapted to various communication models, thereby improving the compatibility of the circuit.

[0051] like Figure 6 As shown, in some embodiments, the protection circuit for serial port communication further includes a second impedance matching circuit 6 , and the second impedance matching circuit 6 is connected to the serial port conversion chip 2 .

[0052] Specifically, the second impedance matching circuit 6 is connected to the serial port conversion chip 2, and is used to limit the input voltage VCC3, so that the pin of the serial port conversion chip 2 obtains the required voltage value, and the matching module can be smoothly set to different 1 or 0, thereby realizing the matching setting of different modes. Through the second impedance matching circuit 6, the signal quality is optimized, so that the matching module sets different voltage signals for the pin of the serial port conversion chip 2 more stably.

[0053] In some embodiments, the second impedance matching circuit 6 includes two second resistors R11 , one end of the two second resistors R11 is electrically connected to a power source, and the other end of the two second resistors R11 is electrically connected to two pins of the serial port conversion chip 2 .

[0054] Specifically, one end of the two second resistors R11 is electrically connected to the power supply VCC3, and the other end of the two second resistors R11 is electrically connected to the two pins GP80 and GP81 of the serial port conversion chip 2. The two second resistors R11 in the second impedance matching circuit 6 match the impedance of the signal so that an accurate and stable voltage signal is obtained when it is transmitted to the pin of the serial port conversion chip 2. Due to the second resistor R11, the second impedance matching circuit 6 reduces signal reflection, optimizes signal quality, effectively protects the signal, and reduces signal loss.

[0055] It should be noted that the resistance value of the second resistor R11 can be adjusted according to the requirements of different serial port conversion chips 2. For example, the second resistor R11 is set to 10 kΩ, and the corresponding pins of the serial port conversion chip 2 obtain 0 and 1 signals.

[0056] The embodiment of the present application further provides a serial communication protection device including: a shell having a receiving cavity formed therein, and the above-mentioned serial communication protection circuit, which is arranged in the shell.

[0057] An embodiment of the present application further provides a serial communication protection system, and the serial communication protection system includes the above-mentioned serial communication protection device.

[0058] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the same. Although the present application has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to replace some of the technical features therein by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions claimed to be protected by the present application.

Claims

1. A protection circuit for serial communication, characterized in that: include: RS485 serial port, serial port conversion chip, lightning surge protection circuit and filtering circuit, the lightning surge protection circuit and the filtering circuit are both located between the RS485 serial port and the serial port conversion chip, and are connected in sequence, wherein the lightning surge protection circuit is provided with a TVS tube, the TVS tube is used to protect the serial port conversion chip communication from lightning surges, one end of the filtering circuit is grounded, and the other end of the filtering circuit is connected to the RS485 serial port.

2. A serial communication protection circuit according to claim 1, characterized in that: Two TVS tubes are arranged in the lightning surge protection circuit, one TVS tube is used for line surge protection of the negative end of the RS485 serial port, and the other TVS tube is used for line surge protection of the positive end of the RS485 serial port, and the other ends of the two TVS tubes are grounded.

3. A serial communication protection circuit according to claim 1, characterized in that: The filter circuit includes two capacitors, one of which is used for anti-interference filtering of the negative end of the RS485 serial port, and the other of which is used for anti-interference filtering of the positive end of the RS485 serial port, and the other ends of the two capacitors are grounded.

4. A serial communication protection circuit according to claim 1, characterized in that: The serial communication protection circuit also includes a first impedance matching circuit, which is located between the serial port conversion chip and the RS485 serial port, and the serial port conversion chip, the first impedance matching circuit, the lightning surge protection circuit and the RS485 serial port are arranged in sequence.

5. A serial communication protection circuit according to claim 4, characterized in that: The first impedance matching circuit includes a first resistor, one end of the TVS tube is electrically connected to the first resistor, and the other end of the TVS tube is grounded.

6. A serial communication protection circuit according to claim 1, characterized in that: The serial port conversion chip is provided with a matching module, and the matching module is used to set different voltage signals for the pins of the serial port conversion chip to adapt to the conversion between different communication models.

7. A serial communication protection circuit according to claim 6, characterized in that: The serial port communication protection circuit further includes a second impedance matching circuit, and the second impedance matching circuit is connected to the serial port conversion chip.

8. A serial communication protection circuit according to claim 7, characterized in that: The second impedance matching circuit includes two second resistors, one end of the two second resistors is electrically connected to a power supply, and the other end of the two second resistors is electrically connected to two pins of the serial port conversion chip respectively.

9. A protection device for serial communication, characterized in that: include: A shell having an accommodating cavity formed therein, and a serial communication protection circuit as described in any one of claims 1 to 8, are arranged in the shell.

10. A serial communication protection system, characterized in that: The serial communication protection system includes the device described in claim 9.

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