CN214751855U - RS485 communication circuit and electronic equipment - Google Patents
RS485 communication circuit and electronic equipment Download PDFInfo
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- CN214751855U CN214751855U CN202120572247.6U CN202120572247U CN214751855U CN 214751855 U CN214751855 U CN 214751855U CN 202120572247 U CN202120572247 U CN 202120572247U CN 214751855 U CN214751855 U CN 214751855U
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Abstract
The utility model discloses a RS485 communication circuit and electronic equipment. The RS485 communication circuit comprises a signal isolation circuit and a signal transmission circuit; the signal isolation circuit comprises a preset chip, the preset chip is respectively connected with a receiving and transmitting control end, a transmitting end and a receiving end of the main control unit, and the preset chip is also connected with an RS485 interface through the signal transmission circuit; the preset chip is a capacitive isolation chip or a magnetic coupling chip. The capacity separation chip or the magnetic coupling chip is adopted to replace the optical coupler to realize signal isolation, so that the problem of low signal transmission rate caused by transmission delay of the optical coupler is avoided, and the method can be further applied to RS485 application occasions with any communication baud rate.
Description
Technical Field
The utility model relates to the field of electronic technology, especially, relate to a RS485 communication circuit and electronic equipment.
Background
The RS485 is an industrial field bus commonly used for communication among different devices in an industrial field, and the bus interface and the master control MCU need to be electrically isolated from each other in terms of safety and practicability.
At present, an isolation circuit built through a common optical coupler is the most common technical scheme in low-speed communication isolation application requirements, the communication baud rate generally can reach 9600bps, but the common optical coupler isolation scheme cannot meet the higher-speed communication requirements. Of course, another scheme is to build an isolation circuit by adding an optical coupler accelerating circuit, and the communication baud rate of the scheme can reach 57600bps, but the scheme cannot be applied to higher-speed communication occasions.
SUMMERY OF THE UTILITY MODEL
A primary object of the utility model is to provide an RS485 communication circuit and electronic equipment aims at solving the technical problem that the isolation scheme of RS485 communication circuit can't be applied to the occasion that the communication baud rate is greater than 57600bps among the prior art.
In order to achieve the above object, the present invention provides an RS485 communication circuit, which includes a signal isolation circuit and a signal transmission circuit; the signal isolation circuit comprises a preset chip, the preset chip is respectively connected with a receiving and transmitting control end, a transmitting end and a receiving end of the main control unit, and the preset chip is also connected with an RS485 interface through the signal transmission circuit; the preset chip is a capacitive isolation chip or a magnetic coupling chip.
Preferably, the signal isolation circuit further comprises a first capacitor and a second capacitor; the first end of the first capacitor is respectively connected with the first power pin of the preset chip and the first power supply, and the second end of the first capacitor and the first grounding pin of the preset chip are connected with a first ground; the first end of the second capacitor is connected with the second power pin of the preset chip and the second power supply respectively, and the second end of the second capacitor and the second grounding pin of the preset chip are connected with the second ground.
Preferably, the first power supply is a power supply of the main control unit, and the second power supply is a power supply of the signal transmission circuit.
Preferably, the signal transmission circuit comprises an RS485 chip, a first resistor, a second resistor and a third resistor; wherein the content of the first and second substances,
a receiving pin of the RS485 chip is respectively connected with a first receiving pin of the preset chip and a first end of the first resistor, a sending pin of the RS485 chip is connected with a first sending pin of the preset chip, an enabling pin of the RS485 chip is connected with a first control pin of the preset chip, a first interface pin of the RS485 chip is respectively connected with a first end of the second resistor and a first end of the RS485 interface, a second interface pin of the RS485 chip is respectively connected with a first end of the third resistor and a second end of the RS485 interface, a power supply pin of the RS485 chip is connected with the second power supply, and a grounding pin of the RS485 chip is connected with a second ground;
the second end of the first resistor is connected with the second power supply;
a second end of the second resistor is connected with the second power supply;
and the second end of the third resistor is connected with the second ground.
Preferably, the signal transmission circuit further includes a third capacitor; and the first end of the third capacitor is connected with the second power supply, and the second end of the third capacitor is connected with the second ground.
Preferably, the signal transmission circuit further includes a fourth resistor, a fifth resistor, and a sixth resistor; wherein the content of the first and second substances,
the fourth resistor is connected in series between the receiving pin of the RS485 chip and the first receiving pin of the preset chip;
the fifth resistor is connected in series between an enable pin of the RS485 chip and a first control pin of the preset chip;
the sixth resistor is connected in series between the sending pin of the RS485 chip and the first sending pin of the preset chip.
Preferably, the RS485 communication circuit further includes an interface protection circuit; the interface protection circuit is connected in series between the signal transmission circuit and the RS485 interface.
Preferably, the interface protection circuit comprises a transient suppressor, a first thermistor and a second thermistor; wherein the content of the first and second substances,
a first end of the transient suppressor is connected with a first end of the second resistor and a first end of the second thermistor respectively, and a second end of the transient suppressor is connected with a first end of the third resistor and a first end of the first thermistor respectively;
the second end of the first thermistor is connected with the second end of the RS485 interface;
and the second end of the second thermistor is connected with the first end of the RS485 interface.
The utility model also provides an electronic equipment, electronic equipment includes as above RS485 communication circuit.
The utility model arranges a signal isolation circuit and a signal transmission circuit in the RS485 communication circuit; the signal isolation circuit comprises a preset chip, the preset chip is respectively connected with a receiving and transmitting control end, a transmitting end and a receiving end of the main control unit, and the preset chip is also connected with an RS485 interface through the signal transmission circuit; the preset chip is a capacitive isolation chip or a magnetic coupling chip. The capacity separation chip or the magnetic coupling chip is adopted to replace the optical coupler to realize signal isolation, so that the problem of low signal transmission rate caused by transmission delay of the optical coupler is avoided, and the method can be further applied to RS485 application occasions with any communication baud rate.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
Fig. 1 is a functional block diagram of an embodiment of the RS485 communication circuit of the present invention;
fig. 2 is an alternative schematic diagram of the RS485 communication circuit of fig. 1.
The reference numbers illustrate:
the objects, features and advantages of the present invention will be further described with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
It should be noted that, if directional indications (such as upper, lower, left, right, front and rear … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative position relationship between the components, the motion situation, etc. in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indications are changed accordingly.
In addition, if there is a description relating to "first", "second", etc. in the embodiments of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions in the embodiments may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should not be considered to exist, and is not within the protection scope of the present invention.
The utility model provides a RS485 communication circuit.
Referring to fig. 1, in an embodiment, the RS485 communication circuit includes a signal isolation circuit 100 and a signal transmission circuit 200; the signal isolation circuit 100 comprises a preset chip U1, the preset chip U1 is respectively connected with a transceiving control end, a transmitting end and a receiving end of a main control unit MCU, and the preset chip U1 is also connected with RS485 interfaces (A1 and B1) through the signal transmission circuit 200; the preset chip U1 is a capacitive isolation chip or a magnetic coupling chip.
The optical coupler is used for signal transmission in an electric-to-optical-to-electric form; the capacitive coupling adopts high-frequency signal modulation and demodulation to transmit an input signal after the input signal is isolated by a capacitor; the magnetic coupling carries out energy transfer through a magnetic field to carry out isolated transmission on signals. Because the conversion that the opto-coupler realized light signal to the signal of telecommunication through emitting diode, the problem that leads to life weak point easily because of the light decay of opto-coupler simultaneously because there is the time delay in the opto-coupler transmission, can lead to signal waveform time delay, therefore the scheme of opto-coupler isolation can not be used to the higher occasion of communication baud rate. When the capacitive coupling and the magnetic coupling are isolated, signals have better following characteristics, the electric gaps and creepage distances on two sides of the isolation are wider, the isolation strength is higher, the capacitive isolation chip or the magnetic coupling chip is adopted to replace the optical coupling for isolation, and the RS485 application of all industrial fields with any communication baud rate can be dealt with.
It can be understood that the signal isolation circuit 100 is used to realize signal isolation between the main control unit MCU and the signal transmission circuit 200. In a specific implementation, the preset chip U1 is a three-channel chip, the transceiver control terminal RE/DE1 of the main control unit MCU sends a control signal to the second control pin V1A of the preset chip U1, and the first control pin V0A of the preset chip U1 transmits the control signal to the signal transmission circuit 200, so as to implement signal reception and transmission control. When the transmitting terminal TXD of the main control unit MCU transmits data to the second transmitting pin V1B of the preset chip U1, the first transmitting pin V0B of the preset chip U1 transmits the data to the signal transmission circuit 200, so that the data is transmitted from the main control unit MCU to the RS485 interface. When the receiving terminal RXD of the main control unit MCU receives data, the data of the RS485 interface is transmitted to the first receiving pin V1D of the preset chip U1 through the signal transmission circuit 200, and the second receiving pin V0D of the preset chip U1 transmits the data to the receiving terminal RXD of the main control unit MCU, so that the data is transmitted from the RS485 interface to the main control unit MCU. Therefore, through the signal isolation circuit 100 and the signal transmission circuit 200, not only the transmission and the reception of data between the MCU and the RS485 interface of the main control unit are realized, but also the electrical isolation of signals is realized.
In the embodiment, the signal isolation circuit 100 and the signal transmission circuit 200 are arranged in the RS485 communication circuit; the signal isolation circuit 100 comprises a preset chip U1, the preset chip U1 is respectively connected with a transceiving control end, a transmitting end and a receiving end of a main control unit MCU, and the preset chip U1 is also connected with an RS485 interface through the signal transmission circuit 200; the preset chip U1 is a capacitive isolation chip or a magnetic coupling chip. The capacity separation chip or the magnetic coupling chip is adopted to replace the optical coupler to realize signal isolation, so that the problem of low signal transmission rate caused by transmission delay of the optical coupler is avoided, and the method can be further applied to RS485 application occasions with any communication baud rate.
Referring to fig. 1 and fig. 2 together, fig. 2 is a schematic diagram of an alternative structure of the RS485 communication circuit of fig. 1.
In this embodiment, the signal isolation circuit 100 further includes a first capacitor C1 and a second capacitor C2; a first end of the first capacitor C1 is connected to a first power supply VDD1 pin and a first power supply VDD1 of the default chip U1, respectively, and a second end of the first capacitor C1 and a first ground pin G1 of the default chip U1 are connected to a first ground GND 1; a first end of the second capacitor C2 is connected to the second power VDD2 pin and the second power VDD2 of the default chip U1, respectively, and a second end of the second capacitor C2 and the second ground pin G2 of the default chip U1 are connected to the second ground GND 2.
The first power supply VDD1 is a power supply of the main control unit MCU, and the second power supply VDD2 is a power supply of the signal transmission circuit 200. By the design of the first capacitor C1 and the second capacitor C2, and the isolation of the first power supply VDD1 from the second power supply VDD2, the reliability of the circuit is improved.
Further, the signal transmission circuit 200 includes an RS485 chip U2, a first resistor R1, a second resistor R2, and a third resistor R3; a receiving pin RO of the RS485 chip U2 is connected to a first receiving pin V1D of the preset chip U1 and a first end of the first resistor R1, a sending pin D of the RS485 chip U2 is connected to a first sending pin V0B of the preset chip U1, enabling pins RE and DE of the RS485 chip U2 are connected to a first control pin V0A of the preset chip U1, a first interface pin a0 of the RS485 chip U2 is connected to a first end of the second resistor R2 and a first end a1 of the RS interface, a second interface pin B0 of the RS485 chip U2 is connected to a first end of the third resistor R3 and a second end B1 of the RS485 interface, a ground pin nd2 of the RS485 chip U2 is connected to a second ground potential 369636, and a power supply pin VCC of the RS485 chip U2 is connected to the second ground potential VDD 2; a second end of the first resistor R1 is connected with the second power supply VDD 2; a second end of the second resistor R2 is connected to the second power supply VDD 2; the second terminal of the third resistor R3 is connected to the second ground GND 2.
In a specific implementation, when the enable pins RE and DE of the RS485 chip U2 are at a low level, the RS485 chip U2 is in a receiving state, and otherwise, the RS485 chip U2 is in a transmitting state.
It can be understood that the first resistor R1 is a pull-up resistor, and keeps the output of the receiving pin RO of the RS485 chip U2 high when the RS485 chip U2 is in the transmitting state. A bus in the RS485 bus is connected between a first end A1 of the RS485 interface and a first interface pin A0 of the RS485 chip U2, a B bus in the RS485 bus is connected between a second end B1 of the RS485 interface and a second interface pin B0 of the RS485 chip U2, a power supply can be pulled up to the A bus by connecting a second resistor R2 on the A bus, a ground of the power supply can be pulled down to the B bus by connecting a third resistor R3 on the B bus, and then the circuit design meets the RS485 bus specification.
Further, the signal transmission circuit 200 further includes a third capacitor C3; the first terminal of the third capacitor C3 is connected to the second power source VDD2, and the second terminal of the third capacitor C3 is connected to the second ground GND 2.
The third capacitor C3 is a decoupling capacitor and is used for filtering and decoupling the input voltage of the RS485 chip U2.
Further, the signal transmission circuit 200 further includes a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6; the fourth resistor R4 is connected in series between the receiving pin RO of the RS485 chip U2 and the first receiving pin V1D of the default chip U1; the fifth resistor R5 is connected in series between the enable pins RE and DE of the RS485 chip U2 and the first control pin V0A of the default chip U1; the sixth resistor R6 is connected in series between the transmission pin D of the RS485 chip U2 and the first transmission pin V0B of the default chip U1.
The fourth resistor R4, the fifth resistor R5, and the sixth resistor R6 are current limiting resistors, and are used for performing current limiting protection on the RS485 chip U2.
Further, the RS485 communication circuit further includes an interface protection circuit 300; the interface protection circuit 300 is connected in series between the signal transmission circuit 200 and the RS485 interface.
In one embodiment, the interface protection circuit 300 includes a transient suppressor TVS1, a first thermistor RT1 and a second thermistor RT 2; wherein a first terminal of the transient suppressor TVS1 is connected to a first terminal of the second resistor R2 and a first terminal of the second thermistor RT2, respectively, and a second terminal of the transient suppressor TVS1 is connected to a first terminal of the third resistor R3 and a first terminal of the first thermistor RT1, respectively; the second end of the first thermistor RT1 is connected with the second end B1 of the RS485 interface; the second end of the second thermistor RT2 is connected with the first end A1 of the RS485 interface.
In a specific implementation, by connecting the transient suppressor TVS1 in series on the a line and the B line of the RS485 bus, when the transient voltage exceeds the normal operating voltage of the circuit, the diode in the transient suppressor TVS1 avalanche, which provides a path for the transient current, so that the circuit will not be over-heated due to breakdown of excess voltage or excess current. Through series connection thermistor on the A line and the B line of RS485 bus, when the first end A1 and the second end B1 at the RS485 interface insert high voltage, thermistor generates heat because of the increase of electric current, and the resistance increases to guarantee that RS485 chip U2 is not damaged by high voltage.
This embodiment passes through signal isolation circuit's design, has ensured the electrical isolation and the power isolation of signal between main control unit and the RS485 chip, and through signal transmission circuit's design, it satisfies RS485 communication standard to have ensured communication, and through interface protection circuit's design, has effectively ensured that the RS485 chip is not damaged, has promoted the reliability of circuit.
The utility model also provides an electronic device, the electronic device includes the RS485 communication circuit as described above, the circuit structure of the RS485 communication circuit of the electronic device can refer to the above-mentioned embodiment, and the description is omitted herein; it can be understood that, since the electronic device of this embodiment adopts the technical solution of the RS485 communication circuit, the electronic device has all the above beneficial effects.
The above is only the preferred embodiment of the present invention, and not the scope of the present invention, all the equivalent structures or equivalent flow changes made by the contents of the specification and the drawings or the direct or indirect application in other related technical fields are included in the patent protection scope of the present invention.
Claims (9)
1. An RS485 communication circuit is characterized by comprising a signal isolation circuit and a signal transmission circuit; the signal isolation circuit comprises a preset chip, the preset chip is respectively connected with a receiving and transmitting control end, a transmitting end and a receiving end of the main control unit, and the preset chip is also connected with an RS485 interface through the signal transmission circuit; the preset chip is a capacitive isolation chip or a magnetic coupling chip.
2. The RS485 communication circuit of claim 1, wherein the signal isolation circuit further comprises a first capacitor and a second capacitor; the first end of the first capacitor is respectively connected with the first power pin of the preset chip and the first power supply, and the second end of the first capacitor and the first grounding pin of the preset chip are connected with a first ground; the first end of the second capacitor is connected with the second power pin of the preset chip and the second power supply respectively, and the second end of the second capacitor and the second grounding pin of the preset chip are connected with the second ground.
3. The RS485 communication circuit of claim 2, wherein the first power supply is a power supply of the master control unit and the second power supply is a power supply of the signal transmission circuit.
4. The RS485 communication circuit of claim 3, wherein the signal transmission circuit comprises an RS485 chip, a first resistor, a second resistor and a third resistor; wherein the content of the first and second substances,
a receiving pin of the RS485 chip is respectively connected with a first receiving pin of the preset chip and a first end of the first resistor, a sending pin of the RS485 chip is connected with a first sending pin of the preset chip, an enabling pin of the RS485 chip is connected with a first control pin of the preset chip, a first interface pin of the RS485 chip is respectively connected with a first end of the second resistor and a first end of the RS485 interface, a second interface pin of the RS485 chip is respectively connected with a first end of the third resistor and a second end of the RS485 interface, a power supply pin of the RS485 chip is connected with the second power supply, and a grounding pin of the RS485 chip is connected with a second ground;
the second end of the first resistor is connected with the second power supply;
a second end of the second resistor is connected with the second power supply;
and the second end of the third resistor is connected with the second ground.
5. The RS485 communication circuit of claim 4, wherein the signal transmission circuit further comprises a third capacitor; and the first end of the third capacitor is connected with the second power supply, and the second end of the third capacitor is connected with the second ground.
6. The RS485 communication circuit of claim 5, wherein the signal transmission circuit further comprises a fourth resistor, a fifth resistor, and a sixth resistor; wherein the content of the first and second substances,
the fourth resistor is connected in series between the receiving pin of the RS485 chip and the first receiving pin of the preset chip;
the fifth resistor is connected in series between an enable pin of the RS485 chip and a first control pin of the preset chip;
the sixth resistor is connected in series between the sending pin of the RS485 chip and the first sending pin of the preset chip.
7. The RS485 communication circuit of claim 4, wherein the RS485 communication circuit further comprises an interface protection circuit; the interface protection circuit is connected in series between the signal transmission circuit and the RS485 interface.
8. The RS485 communication circuit of claim 7, wherein the interface protection circuit comprises a transient suppressor, a first thermistor, and a second thermistor; wherein the content of the first and second substances,
a first end of the transient suppressor is connected with a first end of the second resistor and a first end of the second thermistor respectively, and a second end of the transient suppressor is connected with a first end of the third resistor and a first end of the first thermistor respectively;
the second end of the first thermistor is connected with the second end of the RS485 interface;
and the second end of the second thermistor is connected with the first end of the RS485 interface.
9. An electronic device, comprising the RS485 communication circuit of any one of claims 1 to 8.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120572247.6U CN214751855U (en) | 2021-03-19 | 2021-03-19 | RS485 communication circuit and electronic equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120572247.6U CN214751855U (en) | 2021-03-19 | 2021-03-19 | RS485 communication circuit and electronic equipment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN214751855U true CN214751855U (en) | 2021-11-16 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202120572247.6U Active CN214751855U (en) | 2021-03-19 | 2021-03-19 | RS485 communication circuit and electronic equipment |
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|---|---|
| CN (1) | CN214751855U (en) |
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2021
- 2021-03-19 CN CN202120572247.6U patent/CN214751855U/en active Active
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