Special multifunctional RS485 deconcentrator for grain depot

Abstract

The utility model relates to the technical field of multifunctional RS485 deconcentrators, in particular to a multifunctional RS485 deconcentrator special for a grain depot. The system comprises a microcontroller module, a communication interface module and an overvoltage protection module. According to the utility model, instructions sent by an upper computer are received through the microcontroller module, and the direction of data transmission is automatically distinguished and controlled by using an automatic transceiving circuit in the communication interface module, so that the microcontroller automatically regulates and controls each path to be in a data receiving state or a data sending state; the overvoltage protection module is used for connecting PTC resistors on signal lines of the input end and the output end of the RS485 interface in series, and a TVS tube is connected between the signal lines and the ground, so that short-circuit current is limited, voltage is suppressed, the short-circuit current and the voltage are isolated in an open-circuit fault scene, and the stability and the reliability of the whole system are maintained.

Description

TECHNICAL FIELD

[0001] The utility model relates to multi -functional RS485 brancher technical field, concretely relates to a multi -functional RS485 brancher special for grain depot. BACKGROUND

[0002] A large number of equipment, such as temperature sensor, humidity sensor, ventilation equipment, monitoring camera etc. are often needed to be connected in the grain depot, RS485 brancher can expand one signal into multiple signals, increase the number of connectable equipment on the bus, meet the demand of multiple equipment access in the grain depot.

[0003] Since multi -functional RS485 brancher expands one signal into multiple signals, if each signal is controlled by microcontroller to be in receiving data state or sending data state, not only a lot of time will be wasted, but also data confusion and conflict will be caused during data transmission, in order to automatically identify and control data transmission direction, ensure the correct transmission of data on the bus, avoid data conflict and confusion, therefore, we propose a multi -functional RS485 brancher special for grain depot. UTILITY MODEL CONTENTS

[0004] The utility model discloses a multi -functional RS485 brancher special for grain depot, to solve the problem in the background art.

[0005] In order to achieve the above object, the utility model provides a multi -functional RS485 brancher special for grain depot, including microcontroller module, communication interface module and overvoltage protection module;

[0006] The microcontroller module receives the instruction sent by the host computer, and parses it according to the instruction format, extracts the instruction code, and converts the instruction code into a level signal and transmits it to the communication interface module;

[0007] The communication interface module receives the level signal transmitted by the microcontroller module, converts the level signal into a differential signal by using the RS485 interface chip, and transmits it to the RS485 bus, and automatically identifies and controls the direction of data transmission by the automatic transceiver circuit composed of the SP3485 chip;

[0008] The overvoltage protection module uses PTC resistance and TVS tube to limit short-circuit current when the communication interface module switches data receiving and sending, and suppresses voltage.

[0009] As a further improvement of the technical scheme, the communication interface module includes an interface chip unit and an automatic control unit.

[0010] The interface chip unit converts the level signal from the microcontroller into RS485 differential signal and sends the differential signal to the bus, and converts the received RS485 differential signal on the bus into a level signal for the microcontroller to process.

[0011] The automatic control unit transmits and intelligently controls data to the RS485 bus through the SP3485 chip according to the differential signal converted by the interface chip unit.

[0012] As a further improvement of the technical solution, the interface chip unit sends data to the SP3485 chip through the TXD pin of the single-chip microcomputer, and receives data from the SP3485 chip through the RXD pin of the single-chip microcomputer.

[0013] As a further improvement of the technical solution, the automatic control unit includes an automatic transceiver circuit, wherein the automatic transceiver circuit includes a transistor Q, an SP3485 chip, a bidirectional voltage stabilizing diode D1, a bidirectional voltage stabilizing diode D2, and a bidirectional voltage stabilizing diode D3.

[0014] One end of the resistor R1 is connected to the base of the transistor Q, the other end of the resistor R1 is connected to the TXD pin of the single-chip microcomputer, the collector of the transistor Q is connected to the resistor R2 and the pins 2 and 3 of the SP3485 chip, one end of the resistor R3 is connected to the pin 1 of the SP3485 chip, the other end of the resistor R3 is connected to the RXD pin of the single-chip microcomputer, the pin 4 of the SP3485 chip is connected to the emitter of the transistor Q and the ground, the pin 6 of the SP3485 chip is connected to the resistor R5 and the voltage VCC, the pin 7 of the SP3485 chip is connected to the resistor R4 and the ground, the pin 8 of the SP3485 chip is connected to the voltage VCC and the capacitor C1, the other end of the capacitor C1 is connected to the ground, the pin 6 of the SP3485 chip is connected to the bidirectional voltage stabilizing diode D2 and the bidirectional voltage stabilizing diode D3, the pin 7 of the SP3485 chip is connected to the bidirectional voltage stabilizing diode D1 and the bidirectional voltage stabilizing diode D2, the other ends of the bidirectional voltage stabilizing diode D1 and the bidirectional voltage stabilizing diode D3 are connected to the ground.

[0015] As a further improvement of the technical solution, the pins 6 and 7 of the SP3485 chip in the automatic transceiver circuit are connected in parallel to the bidirectional voltage stabilizing diode D2, the bidirectional voltage stabilizing diode D1, and the bidirectional voltage stabilizing diode D3.

[0016] As a further improvement of the technical solution, the overvoltage protection module is connected in series with a PTC resistor on the signal lines of the input end and the output end of the RS485 interface, and a TVS tube is connected between the signal lines and the ground.

[0017] Compared with the prior art, the utility model has the advantages of:

[0018] The special multifunctional RS485 branch distributor for the grain depot receives the instruction sent by the upper computer through the microcontroller module, analyzes the instruction according to the instruction format, extracts the instruction code, converts the instruction code into a level signal, automatically identifies and controls the direction of data transmission by using the automatic transceiver circuit in the communication interface module, realizes that the microcontroller automatically controls each path to be in a receiving data state or a sending data state, saves time, and can avoid data confusion and conflict;

[0019] The overvoltage protection module connects a PTC resistor in series on the signal lines of the input end and the output end of the RS485 interface, and connects a TVS tube between the signal lines and the ground, limits the short-circuit current, suppresses the voltage, and plays a role in isolation under the open circuit fault scene, thereby maintaining the stability and reliability of the whole system. BRIEF DESCRIPTION OF DRAWINGS

[0020] Fig. 1 It is a whole flow schematic diagram of the utility model;

[0021] Fig. 2 It is a whole detail flow schematic diagram of the utility model;

[0022] Fig. 3 It is an automatic transceiver circuit diagram of the utility model.

[0023] The meanings of various reference numerals in the drawing are as follows:

[0024] 100, microcontroller module; 200, communication interface module; 210, interface chip unit; 220, automatic control unit; 300, overvoltage protection module. DETAILED DESCRIPTION

[0025] The technical scheme in the embodiments of the utility model will be clearly and completely described in combination with the drawings in the utility model, apparently, the described embodiments are only a part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the utility model.

[0026] A large number of devices need to be connected in the grain depot, such as temperature sensors, humidity sensors, ventilation equipment, monitoring cameras and the like, and the RS485 branch distributor can expand one signal into multiple signals, increase the number of devices connectable on the bus, and meet the needs of multiple device access in the grain depot.

[0027] Please refer to Figs. 1-3 The utility model provides a kind of special multifunctional RS485 branch distributor for grain depot, including microcontroller module 100, communication interface module 200 and overvoltage protection module 300;

[0028] The microcontroller module 100 receives the instruction sent by the host computer, parses the instruction according to the instruction format, extracts the instruction code, and converts the instruction code into a level signal and transmits the level signal to the communication interface module 200;

[0029] The communication interface module 200 receives the level signal transmitted by the microcontroller module 100, converts the level signal into a differential signal by using an RS485 interface chip, transmits the differential signal to an RS485 bus, and automatically identifies and controls the direction of data transmission through an automatic transceiver circuit composed of an SP3485 chip.

[0030] The overvoltage protection module 300 uses PTC resistance and TVS tube to limit short-circuit current and suppress voltage when the communication interface module 200 switches between data receiving and sending.

[0031] As shown in Fig. 2 , the communication interface module 200 includes an interface chip unit 210 and an automatic control unit 220;

[0032] The interface chip unit 210 converts the level signal from the microcontroller into an RS485 differential signal and transmits the RS485 differential signal to the bus, and simultaneously converts the RS485 differential signal received from the bus into a level signal for the microcontroller to process;

[0033] The automatic control unit 220 transmits and intelligently controls data to the RS485 bus through an SP3485 chip according to the differential signal converted by the interface chip unit 210;

[0034] When the microcontroller needs to send data to the RS485 bus, it will output a TTL level signal. The TTL level signal first enters the TTL input pin of the level conversion chip. Inside the chip, the differential driver converts the input TTL level signal into an RS485 differential signal that meets the RS485 standard. The converted RS485 differential signal is sent to the RS485 bus through the RS485 output pin of the chip.

[0035] The RS485 differential signal sent by the device on the RS485 bus enters the chip through the RS485 input pin of the level conversion chip. Inside the chip, the differential receiver processes the input RS485 differential signal and converts it into a TTL level signal. The converted TTL level signal is transmitted to the RXD pin of the microcontroller through the TTL output pin of the chip for the microcontroller to process.

[0036] In order to better enable the SP3485 chip to send and receive data, the interface chip unit 210 sends data to the SP3485 chip through the TXD pin of the single-chip microcomputer and receives data from the SP3485 chip through the RXD pin of the single-chip microcomputer.

[0037] When the single-chip microcomputer needs to communicate with external equipment, the data to be sent is output in the form of a digital signal from the TXD pin. For example, in UART (universal asynchronous receiver-transmitter) communication, the TXD pin sends data out one bit at a time in a serial manner according to the set baud rate, data bits, stop bits, and other parameters. The RXD pin is responsible for receiving data sent from external equipment and converting it into a digital signal that the single-chip microcomputer can process. In UART communication, the RXD pin samples and receives the serial data input from the outside according to the set baud rate and other parameters, and restores it to the original data byte. The TXD pin and the RXD pin of the single-chip microcomputer enable the transmission of data and the reception of data, respectively, to facilitate the identification of received data and transmitted data by the SP3485 chip.

[0038] In order to better control the direction of data transmission, the automatic control unit 220 includes an automatic transceiver circuit, wherein the automatic transceiver circuit includes a transistor Q, an SP3485 chip, a bidirectional voltage stabilizing diode D1, a bidirectional voltage stabilizing diode D2, and a bidirectional voltage stabilizing diode D3.

[0039] One end of the resistor R1 is connected to the base of the transistor Q, the other end of the resistor R1 is connected to the TXD pin of the single-chip microcomputer, the collector of the transistor Q is connected to the resistor R2 and the 2 pin and the 3 pin of the SP3485 chip, one end of the resistor R3 is connected to the 1 pin of the SP3485 chip, the other end of the resistor R3 is connected to the RXD pin of the single-chip microcomputer, the 6 pin of the SP3485 chip is connected to the emitter of the transistor Q and to ground, the 6 pin of the SP3485 chip is connected to the resistor R5 and to the voltage VCC, the 7 pin of the SP3485 chip is connected to the resistor R4 and to ground, the 8 pin of the SP3485 chip is connected to the voltage VCC and to the capacitor C1, the other end of the capacitor C1 is connected to ground, the 6 pin of the SP3485 chip is connected to the bidirectional voltage stabilizing diode D2 and to the bidirectional voltage stabilizing diode D3, the 7 pin of the SP3485 chip is connected to the bidirectional voltage stabilizing diode D1 and to the bidirectional voltage stabilizing diode D2, the other end of the bidirectional voltage stabilizing diode D1 and the bidirectional voltage stabilizing diode D3 is connected to ground.

[0040] In the circuit, when the TXD pin of the single-chip microcomputer sends 0, the transistor Q is not conductive, the 3 pin of the SP3485 chip is at high level, the SP3485 chip enters the sending mode, since the 4 pin of the SP3485 chip is grounded, therefore the 6 pin and the 7 pin of the SP3485 chip will transmit 0, when the TXD sends 1, the transistor Q is conductive, the 2 pin of the SP3485 chip is at low level, the SP3485 chip switches to the receiving mode, at this time, the 6 pin and the 7 pin of the SP3485 chip will show high resistance state, the 6 pin and the 7 pin of the SP3485 chip are respectively pulled up and pulled down through the resistance R5 and the resistance R4, the voltage difference between the 6 pin and the 7 pin of the SP3485 chip is the power supply voltage, at this time, the 6 pin and the 7 pin of the SP3485 chip depend on the resistance R5 and the resistance R4 to maintain output 1, in the process of receiving data, the TXD pin usually keeps high level, at this time, the transistor Q is conductive, the 2 pin of the SP3485 chip is at low level, the SP3485 chip is in the receiving mode, then the 1 pin of the SP3485 chip will transmit the data received on the 6 pin and the 7 pin to the RXD pin of the single-chip microcomputer, realizing automatic sending and receiving of data.

[0041] In order to be able to over-voltage protection to the automatic sending and receiving circuit, wherein the 6 pin and the 7 pin of the SP3485 chip in the automatic sending and receiving circuit are connected with the bidirectional voltage stabilizing diode D2, the bidirectional voltage stabilizing diode D1 and the bidirectional voltage stabilizing diode D3 in parallel;

[0042] The bidirectional voltage stabilizing diode has the characteristics that after reverse breakdown within a certain voltage range, the voltage can be stabilized at a specific value, when the voltage on the bus exceeds the stabilized value, the bidirectional voltage stabilizing diode will quickly conduct, clamping the excessively high voltage within a safe range, thereby protecting the SP3485 chip and the subsequent circuit from damage by transient high voltage, in the RS485 network, multiple devices are connected together through the bus, when a device fails or is disturbed to output an abnormally high voltage, the bidirectional voltage stabilizing diode can limit the abnormal voltage within the device, avoiding its influence on other normal devices through the bus, playing a role in protecting the stable operation of the entire communication network;

[0043] In the RS485 communication, due to factors such as distributed capacitance between the transmission line and the ground, common mode voltage may be generated, when the common mode voltage exceeds a certain range, it will affect the communication quality and even damage the equipment, the bidirectional voltage stabilizing diode can clamp the common mode voltage within a certain range, so as to keep it stable, thereby reducing the influence of common mode interference on communication.

[0044] In order to better limit the short-circuit current and suppress the voltage, wherein the over-voltage protection module 300 is connected with a PTC resistance in series on the signal lines of the input end and the output end of the RS485 interface, and a TVS tube is connected between the signal lines and the ground;

[0045] PTC resistor, i.e. positive temperature coefficient thermistor, has a unique characteristic of resistance change with temperature. Under normal working temperature and current, PTC resistor presents a low resistance, which has little influence on the transmission of circuit signal. However, when a short circuit fault occurs at the port, the current flowing through the PTC resistor increases sharply, which causes the temperature of the PTC resistor to rise rapidly due to the Joule heating effect. With the temperature rising, the resistance of the PTC resistor increases rapidly according to the positive temperature coefficient rule, and sometimes the resistance can increase by several orders of magnitude, thereby effectively limiting the further increase of the short circuit current and avoiding serious consequences such as overheating damage and component burnout of the subsequent circuit caused by the excessive short circuit current.

[0046] If a short circuit occurs at a port of the RS485 splitter due to line damage, equipment failure or other reasons, the original normal current path is abnormally short-circuited, and the current becomes very large at this moment. At this moment, the PTC resistor connected in series with the signal line of the port can play a role, and the resistance of the PTC resistor rises rapidly, so that the total resistance of the entire short circuit loop increases. According to Ohm's law, the current will be limited in a relatively safe range under the condition that the supply voltage remains unchanged, thereby protecting the RS485 chip, microcontroller and other circuit elements connected behind to prevent them from being damaged by the excessive current impact.

[0047] TVS tube, i.e. transient voltage suppression diode, has the core characteristics of extremely fast response speed and strong surge absorption capacity. Under normal working voltage, the TVS tube is in the off state, which is equivalent to an open circuit. When an abnormal overvoltage occurs at the port, the voltage across the TVS tube exceeds its avalanche breakdown voltage or clamping voltage, and the TVS tube will quickly enter the avalanche breakdown state or the conduction state, thereby reducing the impedance of the TVS tube to a very low level, clamping the excessive voltage in a safe voltage range, so that the voltage borne by the subsequent circuit will not exceed the voltage withstand limit, thereby protecting the circuit elements from damage caused by the excessive voltage.

[0048] Although the short circuit current is the main problem when a short circuit fault occurs, abnormal voltage fluctuations may also occur at the moment of short circuit. The induced electromotive force generated by the inductive element in the line when the current changes suddenly may cause voltage spikes. At this moment, the TVS tube can quickly respond to clamp these abnormal high voltages, preventing them from damaging the subsequent circuit. In cooperation with the PTC resistor, the response capability to short circuit faults is further improved, and the safety of the circuit is ensured.

[0049] In summary, the working principle of the present scheme is as follows:

[0050] The special multifunctional RS485 branch distributor for the grain depot receives the instruction sent by the upper computer through the microcontroller module 100, analyzes the instruction according to the instruction format, extracts the instruction code, converts the instruction code into a level signal, automatically identifies and controls the direction of data transmission by using the automatic transceiver circuit in the communication interface module 200, realizes the automatic regulation and control of the microcontroller for each road in the receiving data state or the sending data state, not only saves time, but also can avoid data confusion and conflict, the overvoltage protection module 300 is connected with a PTC resistance in series on the signal line of the input end and the output end of the RS485 interface, and a TVS tube is connected between the signal line and the ground, the short-circuit current is limited, the voltage is suppressed, in the open circuit fault scene, the isolation effect is jointly played, the stability and reliability of the whole system are maintained.

[0051] The basic principle, main features and advantages of the utility model are shown and described above. It should be understood by those skilled in the art that the utility model is not limited by the above-mentioned embodiments, the above-mentioned embodiments and the description in the specification are only preferred examples of the utility model, and are not used to limit the utility model, various changes and improvements of the utility model can be made without departing from the spirit and scope of the utility model, and these changes and improvements all fall within the scope of the utility model claimed. The protection scope of the utility model is defined by the appended claims and their equivalents.

Claims

1. A multi-functional RS485 distributor for grain depot, characterized in that: The application relates to a microcontroller module (100), a communication interface module (200) and an overvoltage protection module (300). The microcontroller module (100) receives instructions sent by an upper computer, parses the instructions according to an instruction format, extracts instruction codes, and converts the instruction codes into level signals which are transmitted to the communication interface module (200). The communication interface module (200) receives the level signals transmitted by the microcontroller module (100), converts the level signals into differential signals by using an RS485 interface chip, and transmits the differential signals to an RS485 bus; the automatic transceiving circuit composed of the SP3485 chip automatically identifies and controls the direction of data transmission. The overvoltage protection module (300) uses PTC resistance and a TVS tube to limit short-circuit current and suppress voltage when the communication interface module (200) switches between data receiving and sending.

2. The multi-functional RS485 distributor for grain depot according to claim 1, characterized in that: The communication interface module (200) comprises an interface chip unit (210) and an automatic control unit (220). The interface chip unit (210) converts the level signals from the microcontroller into RS485 differential signals and transmits the differential signals to the bus, and converts the received RS485 differential signals on the bus into level signals for the microcontroller. The automatic control unit (220) transmits and intelligently controls data to the RS485 bus by using the SP3485 chip according to the differential signals converted by the interface chip unit (210).

3. The multi-functional RS485 distributor for grain depot according to claim 2, characterized in that: The interface chip unit (210) transmits data to the SP3485 chip through the TXD pin of the single-chip microcomputer and receives data from the SP3485 chip through the RXD pin of the single-chip microcomputer.

4. The multi-functional RS485 distributor for grain depot according to claim 2, characterized in that: The automatic control unit (220) comprises an automatic transceiving circuit, wherein the automatic transceiving circuit comprises a transistor Q, an SP3485 chip, a bidirectional voltage stabilizing diode D1, a bidirectional voltage stabilizing diode D2 and a bidirectional voltage stabilizing diode D3. One end of the resistor R1 is connected to the base of the transistor Q, the other end of the resistor R1 is connected to the TXD pin of the single-chip microcomputer, the collector of the transistor Q is connected to the resistor R2 and the 2th and 3th pins of the SP3485 chip, one end of the resistor R3 is connected to the 1th pin of the SP3485 chip, the other end of the resistor R3 is connected to the RXD pin of the single-chip microcomputer, the 4th pin of the SP3485 chip is connected to the emitter of the transistor Q and the ground, the 6th pin of the SP3485 chip is connected to the resistor R5 and the voltage VCC, the 7th pin of the SP3485 chip is connected to the resistor R4 and the ground, the 8th pin of the SP3485 chip is connected to the voltage VCC and the capacitor C1, the other end of the capacitor C1 is connected to the ground, the 6th pin of the SP3485 chip is connected to the bidirectional voltage stabilizing diode D2 and the bidirectional voltage stabilizing diode D3, the 7th pin of the SP3485 chip is connected to the bidirectional voltage stabilizing diode D1 and the bidirectional voltage stabilizing diode D2, the other ends of the bidirectional voltage stabilizing diode D1 and the bidirectional voltage stabilizing diode D3 are connected to the ground.

5. The multi-functional RS485 distributor for grain depot according to claim 4, characterized in that: The 6th and 7th pins of the SP3485 chip in the automatic transceiving circuit are connected in parallel to the bidirectional voltage stabilizing diode D2, the bidirectional voltage stabilizing diode D1 and the bidirectional voltage stabilizing diode D3.

6. The multi-functional RS485 distributor for grain depot according to claim 1, characterized in that: The overvoltage protection module (300) connects a PTC resistor in series on the signal line of the input and output of RS485 interface, and connects a TVS tube between the signal line and the ground.

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