CN216930013U

CN216930013U - RS485 self-receiving and transmitting communication device and system

Info

Publication number: CN216930013U
Application number: CN202220610774.6U
Authority: CN
Inventors: 胡广建; 李清石; 刘强
Original assignee: Shandong Inspur Science Research Institute Co Ltd
Current assignee: Shandong Inspur Science Research Institute Co Ltd
Priority date: 2022-03-21
Filing date: 2022-03-21
Publication date: 2022-07-08
Anticipated expiration: 2032-03-21

Abstract

The application provides an RS485 is from receiving and dispatching communication device and system, wherein, this RS485 includes from receiving and dispatching communication device: the signal isolation module is used for receiving and/or sending asynchronous communication signals, and the RS485 self-transceiving module. The first optical coupling unit, the second optical coupling unit and the third optical coupling unit of the signal isolation module are respectively connected with the controller to receive asynchronous communication signals from the controller, and the asynchronous communication signals are electrically isolated or RS485 signals subjected to electrical isolation are sent to the controller from the input signals of the transceiver module. The RS485 self-receiving and sending module is respectively connected with the first optical coupling unit, the second optical coupling unit and the third optical coupling unit of the signal isolation module so as to generate self-receiving and sending control signals through the electrically isolated asynchronous communication signals of the first optical coupling unit.

Description

RS485 self-receiving and transmitting communication device and system

Technical Field

The application relates to the technical field of communication, in particular to an RS485 self-transceiving communication device and system.

Background

The RS485 bus is a standard defined to balance the electrical characteristics of drivers and receivers in digital multipoint systems, which is defined by the telecommunications industry association and the electronics industry consortium. RS485 employs balanced transmission and differential reception, and thus has the capability of suppressing common mode interference. The bus transceiver has high sensitivity and can detect the voltage as low as 200mv, so that the transmission signal can be recovered beyond kilometer.

Due to the facts that the RS485 can transmit long-distance information, is high in anti-interference capacity and the like, the RS485 converter is generally used in the fields of security communication and the like. However, when the RS485 signal is converted from the line signal, the interference of the signal is easily generated, and generally, the line has a history of high voltage (lightning strike and leakage), so that the RS485 converter of the individual device of the system has a problem, and the global reception is affected.

SUMMERY OF THE UTILITY MODEL

The embodiment of the application provides an RS485 self-receiving and transmitting communication device and system, which are used for reducing or eliminating the influence on global reception when a signal conversion circuit of the RS485 is connected in series with high voltage, and preventing the communication of the RS485 from being interfered.

In one aspect, an embodiment of the present application provides an RS485 self-transceiving communication device, where the RS485 self-transceiving communication device includes: the signal isolation module is used for receiving and/or sending asynchronous communication signals, and the RS485 self-transceiving module.

The first optical coupling unit, the second optical coupling unit and the third optical coupling unit of the signal isolation module are respectively connected with the controller to receive asynchronous communication signals from the controller, and the asynchronous communication signals are electrically isolated or RS485 signals subjected to electrical isolation are sent to the controller from the input signals of the transceiver module. The RS485 self-receiving and sending module is respectively connected with the first optical coupling unit, the second optical coupling unit and the third optical coupling unit of the signal isolation module so as to generate self-receiving and sending control signals through the electrically isolated asynchronous communication signals of the first optical coupling unit.

In one implementation manner of the present application, the RS485 self-transceiving communication device further includes: and (5) isolating the power supply module. The first end of the isolation power supply module is connected with the first power supply input end of the second optical coupling unit. The second end of the isolation power supply module is respectively connected with the power supply input end of the first optical coupling unit, the second power supply input end of the second optical coupling unit, the power supply input end of the third optical coupling unit and the power supply input end of the RS485 self-receiving and transmitting module.

In one implementation manner of the present application, the RS485 self-transceiving communication device further includes: and a protection module. The protection module comprises at least three transient suppression diodes TVS which are respectively connected with the RS485 self-receiving and transmitting module.

In one implementation manner of the present application, the first optical coupling unit includes: the circuit comprises a first resistor, a second resistor and a first optical coupler. One end of the first resistor is connected with the controller, and the other end of the first resistor is connected with the anode of the first optocoupler. One end of the second resistor is used as a power input end of the first optical coupling unit and is connected with the isolation power supply module. The other end of the second resistor is respectively connected with a collector of the first optocoupler and the RS485 self-transceiving module.

In one implementation manner of the present application, the second optical coupling unit includes: the circuit comprises a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a second optocoupler and a first capacitor. One end of the third resistor is connected with the controller and the fourth resistor respectively, and the other end of the third resistor is connected with the negative electrode of the second optocoupler. One end of the fifth resistor is used as a first power input end of the second optocoupler unit and is connected with the isolation power module and the fourth resistor respectively. The other end of the fifth resistor is connected with the anode of the second optocoupler. One end of the sixth resistor is used as a second power input end of the second optical coupling unit and is connected with the isolation power module. The other end of the sixth resistor is connected with a collector of the second optocoupler and one end of the seventh resistor respectively. The other end of the seventh resistor is connected with one end of the first capacitor and the RS485 self-transceiving module respectively. The other end of the first capacitor is connected with an emitting electrode of the second optocoupler.

In one implementation manner of the present application, the third optical coupling unit includes: eighth resistance, ninth resistance, tenth resistance, third opto-coupler. One end of the eighth resistor is connected with one end of the controller and one end of the ninth resistor respectively, and the other end of the eighth resistor is connected with a collector of the third optocoupler. The other end of the ninth resistor is used as a first input end in the power input end of the third optocoupler unit and is connected with the isolation power supply module. One end of the tenth resistor is connected with the anode of the third optical coupler, and the other end of the tenth resistor is used as a second input end in the power input end of the third optical coupler unit and connected with the isolation power module. And the negative electrode of the third optocoupler is connected with the RS485 self-transceiving module.

In one implementation of the present application, the RS485 self-transceiver module includes: the circuit comprises a transceiving chip, an eleventh resistor, a twelfth resistor and a communication port. The first end of the transceiver chip is connected with the first optical coupling unit, the second end of the transceiver chip is connected with the second optical coupling unit, and the third end of the transceiver chip is connected with the third optical coupling unit. And the fourth end of the transceiving chip is used as a first input end in the power input end of the RS485 self-transceiving module and is connected with the isolation power module. And the fifth end of the transceiver chip is respectively connected with the eleventh resistor and the first end of the communication port. And the sixth end of the transceiver chip is respectively connected with one end of the twelfth resistor and the second end of the communication port. The other end of the twelfth resistor is used as a second input end in the power input end of the RS485 self-receiving and transmitting module and is connected with the isolation power module.

In one implementation of the present application, an isolated power supply module includes: the power supply comprises a power supply chip, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor and an eighth capacitor. One end of the second capacitor is used as the first end of the isolation power supply module and is respectively connected with one end of the third capacitor and the first end of the power supply chip. The other end of the second capacitor is connected with the other end of the third capacitor and the second end of the power supply chip respectively. One end of the fourth capacitor is used as the second end of the isolation power supply module and is respectively connected with the third end of the power supply chip, one end of the fifth capacitor, one end of the sixth capacitor, one end of the seventh capacitor and one end of the eighth capacitor. The other end of the fourth capacitor is connected with the fourth end of the power chip, the other end of the fifth capacitor, the other end of the sixth capacitor, the other end of the seventh capacitor and the other end of the eighth capacitor respectively.

In one implementation of the present application, a protection module includes: the first TVS, the second TVS and the third TVS. One end of the first TVS is connected with the first end of the communication port of the RS485 self-transceiving module and one end of the second TVS respectively. The other end of the second TVS is connected with the second end of the communication port of the RS485 self-transceiving module and one end of the third TVS respectively.

On the other hand, the embodiment of the application also provides an RS485 self-receiving and transmitting communication system, and the RS485 self-receiving and transmitting communication system comprises a controller, an RS485 self-receiving and transmitting communication device connected with the controller, and a plurality of communication terminals connected with the RS485 self-receiving and transmitting communication device. Wherein, RS485 includes from receiving and dispatching communication device: the signal isolation module is used for receiving and/or sending asynchronous communication signals, and the RS485 self-transceiving module.

This application can realize carrying out the opto-coupler isolation to the signal that comes from the controller through above-mentioned scheme, then carry out the receiving and dispatching control certainly of RS485 signal, and then when reducing or eliminating RS 485's signal switching circuit and concatenating high voltage, give the influence that global reception brought, prevent that RS 485's communication from receiving the interference.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

fig. 1 is a schematic structural diagram of an RS485 self-transceiving communication device in an embodiment of the present application;

fig. 2 is a schematic circuit diagram of a first optical coupling unit in an RS485 self-transmitting/receiving communication device in an embodiment of the present application;

fig. 3 is a schematic circuit diagram of a second optical coupling unit in an RS485 self-transceiving communication device in an embodiment of the present application;

fig. 4 is a schematic circuit diagram of a third optical coupling unit in an RS485 self-transceiving communication device in an embodiment of the present application;

fig. 5 is a schematic circuit diagram of an RS485 self-transceiver module in an RS485 self-transceiver communication device according to an embodiment of the present disclosure;

fig. 6 is a schematic circuit diagram of an isolated power supply module in an RS485 self-transceiver communication device according to an embodiment of the present disclosure;

fig. 7 is a schematic structural diagram of an RS485 self-transceiving communication system in an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be described in detail and completely with reference to the following specific embodiments of the present application and the accompanying drawings. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The embodiment of the application provides an RS485 receives and dispatches communication device and system certainly, when reducing or eliminating RS 485's signal conversion circuit and concatenating high voltage, give the influence that global reception brought, prevent that RS 485's communication from receiving the interference.

Various embodiments of the present application are described in detail below with reference to the accompanying drawings.

Fig. 1 is a self-transceiving communication device of RS485 according to an embodiment of the present application, and as shown in fig. 1, the self-transceiving communication device 100 of RS485 includes: the signal isolation module 110 for receiving and/or transmitting asynchronous communication signals, and the RS485 self-transceiving module 120.

The first optical coupler unit 111, the second optical coupler unit 112, and the third optical coupler unit 113 of the signal isolation module 110 are respectively connected to the controller 130 to receive the asynchronous communication signal from the controller 130, and electrically isolate the asynchronous communication signal or send the electrically isolated RS485 input signal from the transceiver module 120 to the controller 130. The RS485 self-transceiving module 120 is respectively connected to the first optical coupler unit 111, the second optical coupler unit 112, and the third optical coupler unit 113 of the signal isolation module 110, so as to generate a self-transceiving control signal through the electrically isolated asynchronous communication signal of the first optical coupler unit 111.

In this embodiment, the signal isolation module 110 may electrically isolate a Universal Asynchronous Receiver/Transmitter (UART) signal, so that only logic functions are transmitted between the controller 130 and the RS485 self-transceiver module 120. The first optical coupling unit 111 may enable the RS485 to generate a self-transceiving control signal from a transceiving chip in the transceiving module 120, thereby completing a self-transceiving function of the RS485 and communicating with the external communication terminal 160. The controller 130 may be a central controller CPU.

As shown in fig. 1, the RS485 self-transceiving communication device 100 further includes: isolating the power module 140.

A first end of the isolated power supply module 140 is connected to a first power supply input end of the second optical coupling unit 112. The second end of the isolation power module 140 is connected to the power input end of the first optical coupling unit 111, the second power input end of the second optical coupling unit 112, the power input end of the third optical coupling unit 113, and the power input end of the RS485 self-transceiving module 120, respectively.

Through signal isolation module and isolation power module, can carry out electrical isolation to RS485 from transceiver module more effectively, effectively reduce the RS485 communication trouble that external interference caused.

In one embodiment of the present application, the RS485 self-transceiving communication device 100 further comprises: a protection module 150. The protection module 150 includes at least three Transient Voltage Supressors (TVS), which are respectively connected to the RS485 self-transceiver module 120.

RS485 is the industrial control bus, and the environment is complicated, and the interference is strong, uses TVS diode effectual to prevent RS485 communication port to receive outside electrostatic discharge to disturb, further protection internal device.

In the embodiment of the present application, a schematic circuit diagram of the first optical coupler unit 111, as shown in fig. 2, includes: first resistance R529, second resistance R527, first opto-coupler U97.

One end of the first resistor R529 is connected to the controller 130, and the other end of the first resistor R529 is connected to the anode of the first optical coupler U97. One end of the second resistor R527 is used as a power input end of the first optical coupling unit 111, and is connected to the isolated power supply module. The other end of the second resistor R527 is respectively connected with a collector electrode of the first optocoupler U97 and the RS485 self-transceiving module. The negative electrode of the first optical coupler U97 is grounded, and the emitter of the first optical coupler U97 is grounded.

The type of the first optocoupler U97 may include TLP2301_11-4M1S, or other types of optocouplers. The second resistor R527 is a pull-up resistor, and may have a resistance of 4.7 kohms.

In this embodiment of the application, the first optical coupler U97 may perform optical coupling isolation on a signal, and then convert the signal into a self-transceiving control signal, specifically:

when the RS485 self-transceiving module is in a data receiving state, when no data exists, the positive electrode of the first optical coupler U97 is in a high level, the first optical coupler U97 is conducted, and the collector of the first optical coupler U97 is enabled in a low level mode. At this time, the RS485 receives valid data from the transceiver module, and the transceiver chip is in an accepting state.

When data 1 is transmitted, the positive electrode of the first optical coupler U97 is at a high level, the first optical coupler U97 is turned on, and the collector of the first optical coupler U97 is at a low level. At this time, the RS485 receives valid data from the transceiver module, the driver of the transceiver chip thereof is changed to a high-resistance state, so that the transmitting end of the transceiver chip U30 is disconnected from the output end of the chip driver (as shown in fig. 5), the voltage between the driver output end a and the driver output end B depends on their respective pull-up and pull-down resistors, the driver output end a is at a high level, the driver output end B is at a low level, and the transceiver chip outputs a logic 1.

When data 1 is transmitted, the positive electrode of the first optocoupler U97 is at a low level, the first optocoupler U97 is turned off, and the collector of the first optocoupler U97 is at a high level. At this time, the RS485 driver from the transceiver module is enabled, the fourth pin of the transceiver chip is at a low level, the driver will have a driver output terminal a of 0, a driver output terminal B of 1, and the transceiver chip outputs a logic 0.

Through this application above-mentioned scheme, can realize RS485 receive and dispatch signal certainly to prevent that RS 485's communication from receiving the interference of external high voltage.

In the embodiment of the present application, a schematic circuit diagram of the second optical coupler unit 112 is shown in fig. 3, and includes: the circuit comprises a third resistor R688, a fourth resistor R721, a fifth resistor R689, a sixth resistor R687, a seventh resistor R686, a second optocoupler U120 and a first capacitor C331. The model of the second optocoupler U120 may be TLP2301_11-4M 1S.

One end of the third resistor R688 is connected with the controller 130 and the fourth resistor R721 respectively, and the other end of the third resistor R688 is connected with the negative electrode of the second optocoupler U120. One end of the fifth resistor R689 serves as a first power input end of the second optical coupling unit, and is connected to the isolation power module and the fourth resistor R721 respectively. The other end of the fifth resistor R689 is connected with the anode of the second optocoupler U120. One end of the sixth resistor R687 is used as a second power input end of the second optical coupling unit and is connected with the isolation power supply module. The other end of the sixth resistor R687 is connected to the collector of the second optocoupler U120 and one end of the seventh resistor R686, respectively. The other end of the seventh resistor R686 is connected to one end of the first capacitor C331 and the RS485 self-transceiving module, respectively. The other end of the first capacitor C331 is connected to the emitter of the second optocoupler U120 and grounded.

Fourth resistance R721 in this application is for reserving the resistance in the in-service use process, adds fourth resistance R721 in the in-service use process, can promote the pull-up ability of signal to prevent that the RS485 module from receiving the influence of the spurious triggering of signal. In addition, when the model is SP3485EN-L and the transceiver chip similar to the model is adopted in the application, the fourth pin DI of the transceiver chip needs to receive signals, so that the signals can be provided to the fourth pin DI after the optical coupling isolation signals are carried out by the second optical coupler U120. If the type that the fourth pin of the transceiver chip does not need to receive signals, for example, MAX3088, is adopted, the first capacitor C331 may be replaced with a 0 ohm resistor, and the grounding may be performed, so that the normal RS485 self-transceiver function may be realized.

In the embodiment of the present application, a schematic circuit diagram of the third optical coupler unit 113, as shown in fig. 4, includes: an eighth resistor R684, a ninth resistor R685, a tenth resistor R533, and a third optocoupler U98. The model of the third optocoupler U98 may be TLP2301_11-4M 1S.

One end of the eighth resistor R684 is connected to one end of the controller 130 and one end of the ninth resistor R685, respectively, and the other end of the eighth resistor R684 is connected to the collector of the third optocoupler U98. The other end of the ninth resistor R685 is used as a first input end of the power input ends of the third optical coupling unit and connected to the isolation power module 140. One end of the tenth resistor R533 is connected to the anode of the third optocoupler U98, and the other end of the tenth resistor R533 is used as a second input end of the power input ends of the third optocoupler unit and connected to the isolated power supply module 140. And the negative electrode of the third optocoupler U98 is connected with an RS485 self-transceiving module. The emitter of the third optical coupler U98 is grounded.

In the embodiment of the present application, a schematic circuit diagram of the RS485 self-transceiver module is shown in fig. 5, and includes: a transceiver chip U30, an eleventh resistor R521, a twelfth resistor R523 and a communication port J20. In the embodiment of the present application, the transceiver chip U30 has a model number SP3485EN-L, and the communication port J20 may have a model number DB2 ERC-3.81-3P-GN.

A first end (a second pin RE and a third pin DE) of the transceiver chip U30 is connected to the first optical coupler unit 111, a second end (a fourth pin DI) of the transceiver chip U30 is connected to the second optical coupler unit 112, and a third end (a first pin RO) of the transceiver chip U30 is connected to the third optical coupler unit 113. The fourth terminal (sixth pin VCC) of the transceiver chip U30 is used as the first input terminal of the RS485 self-transceiver module and is connected to the isolated power supply module 140. The fifth terminal (the seventh pin B) of the transceiver chip U30 is connected to the eleventh resistor R521 and the first terminal of the communication port J20, respectively. A sixth terminal (sixth pin a) of the transceiver chip U30 is connected to one end of the twelfth resistor R523 and the second terminal of the communication port J20, respectively. The other end of the twelfth resistor R523 is used as a second input end of the RS485 self-receiving and transmitting module and is connected to the isolation power supply module 140. The fifth pin GND of the transceiver chip U30 is grounded. The communication port J20 is externally connected with an RS485 twisted pair cable and is used for RS485 communication.

In fig. 5, the protection module includes: a first TVS D78, a second TVS D80, and a third TVS D82. The models of the first TVS D78, the second TVS D80 and the third TVS D82 can be selected from SMCJ6_5 CA.

One end of the first TVS D78 is connected to the first end of the communication port of the RS485 self-transceiver module and one end of the second TVS D80, respectively. The other end of the second TVS D80 is connected to the second end of the RS485 self transceiver module and one end of the third TVS D82, respectively.

In the embodiment of the present application, the circuit schematic diagram of the isolated power module 140, as shown in fig. 6, includes: a power chip PS2, a second capacitor C340, a third capacitor C341, a fourth capacitor C335, a fifth capacitor C336, a sixth capacitor C337, a seventh capacitor C338, and an eighth capacitor C339. The model of the power chip PS2 may be RB-3333 SHP.

One end of the second capacitor C340 is used as the first end of the isolated power module 140, and is connected to one end of the third capacitor C341 and the first end of the power chip PS2, respectively. The other end of the second capacitor C340 is connected to the other end of the third capacitor C341 and the second end of the power chip PS 2. One end of the fourth capacitor C335 serves as the second end of the isolated power module 140, and is connected to the third end of the power chip PS2, one end of the fifth capacitor C336, one end of the sixth capacitor C337, one end of the seventh capacitor C338, and one end of the eighth capacitor C339, respectively. The other end of the fourth capacitor C335 is connected to the fourth end of the power chip PS2, the other end of the fifth capacitor C336, the other end of the sixth capacitor C337, the other end of the seventh capacitor C338, and the other end of the eighth capacitor C339, respectively.

This application adopts the mode that power keeps apart, signal opto-coupler keeps apart, can effectively reduce the RS485 communication trouble that external disturbance caused. According to the technical scheme, the RS485 self-receiving module supports the self-receiving function, and the design cost of the provided technical scheme is low.

Fig. 7 is a schematic structural diagram of an RS485 self-transceiving communication system provided in an embodiment of the present application, where the system includes: the system comprises a controller, an RS485 self-transceiving communication device connected with the controller, and a plurality of communication terminals connected with the RS485 self-transceiving communication device. Wherein, RS485 includes from receiving and dispatching communication device: the signal isolation module is used for receiving and/or sending asynchronous communication signals, and the RS485 self-transceiving module.

The embodiments in the present application are described in a progressive manner, and the same and similar parts among the embodiments can be referred to each other, and each embodiment focuses on the differences from the other embodiments. Particularly, for the RS485 self-transceiving communication system embodiment, since it is basically similar to the device embodiment, the description is relatively simple, and for the relevant points, refer to the partial description of the device embodiment.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The above description is only an example of the present application and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. An RS485 self-transceiving communication device, wherein the RS485 self-transceiving communication device comprises: the signal isolation module is used for receiving and/or sending asynchronous communication signals, and the RS485 self-transceiving module;

the first optical coupling unit, the second optical coupling unit and the third optical coupling unit of the signal isolation module are respectively connected with a controller so as to receive the asynchronous communication signal from the controller, electrically isolate the asynchronous communication signal or send the electrically isolated input signal of the RS485 self-transceiving module to the controller;

the RS485 self-receiving and transmitting module is respectively connected with the first optical coupling unit, the second optical coupling unit and the third optical coupling unit of the signal isolation module, so that the asynchronous communication signals after the electrical isolation of the first optical coupling unit can be generated into self-receiving and transmitting control signals.

2. The RS485 self-transceiving communication device according to claim 1, wherein the RS485 self-transceiving communication device further comprises: an isolated power supply module;

the first end of the isolation power supply module is connected with the first power supply input end of the second optical coupling unit;

and the second end of the isolation power supply module is respectively connected with the power supply input end of the first optical coupling unit, the second power supply input end of the second optical coupling unit, the power supply input end of the third optical coupling unit and the power supply input end of the RS485 self-transceiving module.

3. The RS485 self-transceiving communication device according to claim 1, wherein the RS485 self-transceiving communication device further comprises: a protection module;

the protection module comprises at least three transient suppression diodes TVS which are respectively connected with the RS485 self-transceiving module.

4. The RS485 self-transceiving communication device according to claim 1, wherein the first optical coupling unit comprises: the circuit comprises a first resistor, a second resistor and a first optical coupler;

one end of the first resistor is connected with the controller, and the other end of the first resistor is connected with the anode of the first optocoupler;

one end of the second resistor is used as a power input end of the first optical coupling unit and is connected with an isolation power supply module; the other end of the second resistor is connected with the collector of the first optocoupler and the RS485 self-transceiving module respectively.

5. The RS485 self-transceiving communication device according to claim 1, wherein the second optical coupling unit comprises: the circuit comprises a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a second optocoupler and a first capacitor;

one end of the third resistor is connected with the controller and the fourth resistor respectively, and the other end of the third resistor is connected with the negative electrode of the second optocoupler;

one end of the fifth resistor is used as a first power input end of the second optocoupler unit and is respectively connected with the isolation power module and the fourth resistor; the other end of the fifth resistor is connected with the anode of the second optocoupler;

one end of the sixth resistor is used as a second power supply input end of the second optical coupling unit and is connected with an isolation power supply module; the other end of the sixth resistor is connected with a collector of the second optocoupler and one end of the seventh resistor respectively;

the other end of the seventh resistor is respectively connected with one end of the first capacitor and the RS485 self-transceiving module; the other end of the first capacitor is connected with an emitting electrode of the second optocoupler.

6. The RS485 self-transceiving communication device according to claim 1, wherein the third optical coupling unit comprises: an eighth resistor, a ninth resistor, a tenth resistor and a third optocoupler;

one end of the eighth resistor is connected with the controller and one end of the ninth resistor respectively, and the other end of the eighth resistor is connected with a collector of the third optocoupler;

the other end of the ninth resistor is used as a first input end in the power supply input ends of the third optical coupling unit and is connected with an isolation power supply module;

one end of the tenth resistor is connected with the anode of the third optocoupler, and the other end of the tenth resistor is used as a second input end of the power input ends of the third optocoupler unit and is connected with an isolation power supply module;

and the negative electrode of the third optocoupler is connected with the RS485 self-transceiving module.

7. The RS485 self-transceiving communication device of claim 1, wherein the RS485 self-transceiving module comprises: the receiving and transmitting chip, the eleventh resistor, the twelfth resistor and the communication port;

the first end of the transceiver chip is connected with the first optical coupler unit, the second end of the transceiver chip is connected with the second optical coupler unit, and the third end of the transceiver chip is connected with the third optical coupler unit;

the fourth end of the transceiver chip is used as the first input end of the power input ends of the RS485 self-transceiver module and is connected with the isolation power module;

a fifth end of the transceiver chip is connected with the eleventh resistor and the first end of the communication port respectively;

a sixth end of the transceiver chip is connected with one end of the twelfth resistor and the second end of the communication port respectively;

the other end of the twelfth resistor is used as a second input end of the RS485 self-receiving and transmitting module and is connected with the isolation power supply module.

8. The RS485 self-transceiving communication device of claim 2, wherein the isolated power module comprises: the power supply chip, the second capacitor, the third capacitor, the fourth capacitor, the fifth capacitor, the sixth capacitor, the seventh capacitor and the eighth capacitor;

one end of the second capacitor is used as the first end of the isolation power supply module and is respectively connected with one end of the third capacitor and the first end of the power supply chip; the other end of the second capacitor is connected with the other end of the third capacitor and the second end of the power supply chip respectively;

one end of the fourth capacitor is used as the second end of the isolation power supply module and is respectively connected with a third end of the power supply chip, one end of the fifth capacitor, one end of the sixth capacitor, one end of the seventh capacitor and one end of the eighth capacitor;

the other end of the fourth capacitor is connected with the fourth end of the power chip, the other end of the fifth capacitor, the other end of the sixth capacitor, the other end of the seventh capacitor and the other end of the eighth capacitor respectively.

9. The RS485 self-transceiving communication device of claim 3, wherein the protection module comprises: a first TVS, a second TVS, a third TVS;

one end of the first TVS is connected with the first end of the communication port of the RS485 self-transceiving module and one end of the second TVS respectively;

the other end of the second TVS is connected with the second end of the communication port of the RS485 self-transceiving module and one end of the third TVS respectively.

10. An RS485 self-transceiving communication system, wherein the RS485 self-transceiving communication system comprises: the system comprises a controller, an RS485 self-receiving and transmitting communication device connected with the controller, and a plurality of communication terminals connected with the RS485 self-receiving and transmitting communication device; wherein, RS485 receives and dispatches communication device certainly includes: the signal isolation module is used for receiving and/or sending asynchronous communication signals, and the RS485 self-transceiving module;