CN220823090U - RS485 communication circuit, circuit board and industrial control equipment - Google Patents
RS485 communication circuit, circuit board and industrial control equipment Download PDFInfo
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- CN220823090U CN220823090U CN202322607561.5U CN202322607561U CN220823090U CN 220823090 U CN220823090 U CN 220823090U CN 202322607561 U CN202322607561 U CN 202322607561U CN 220823090 U CN220823090 U CN 220823090U
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Abstract
The application provides an RS485 communication circuit, a circuit board and industrial control equipment, relates to the technical field of electronic circuits, and solves the problem that data exchange among equipment is wrong due to stagnation of an enabling pin of an RS485 communication chip when equipment is down.
Description
Technical Field
The application relates to the technical field of electronic circuits, in particular to an RS485 communication circuit, a circuit board and industrial control equipment.
Background
For the heat pump system, the devices are usually communicated through an RS485 bus, namely, a plurality of devices, such as industrial control devices of a main control board, a frequency conversion board and the like, are mounted on the same bus. In the related art, an RS485 communication chip is generally required to be used when communication is performed by using an RS485 bus. Two enabling pins are arranged on the RS485 communication chip and are respectively used for controlling the RS485 communication chip to enter a sending mode or a receiving mode, namely controlling the opening and closing of a sending channel and a receiving channel.
When a circuit board of one device in the system fails and is down, an enabling pin of the RS485 communication chip may be stopped at a certain fixed level, so that the chip can enter another mode erroneously, normal operation of the whole RS485 bus is limited, data exchange cannot be performed normally, and reliability and stability of the heat pump system are affected.
Disclosure of utility model
The application provides an RS485 communication circuit, a circuit board and industrial control equipment, which solve the problem of error data exchange among equipment caused by stagnation of an enabling pin of an RS485 communication chip when the equipment is down.
In a first aspect, the application provides an RS485 communication circuit, which comprises an RS485 communication chip, and further comprises a signal access unit, a switch control unit and an optocoupler isolation unit.
The signal access unit comprises an input capacitor, and is used for accessing the PWM signal output by the main control module through the enabling signal transmitting end and performing blocking processing on the PWM signal through the input capacitor;
The input end of the switch control unit is connected with the output end of the signal access unit so as to be connected with the PWM signal output by the signal access unit, and the switch control unit is used for performing switch control according to the PWM signal;
The input end of the optical coupler isolation unit is connected with the output end of the switch control unit, the output end of the optical coupler isolation unit is connected with two enabling pins of the RS485 communication chip, and the optical coupler isolation unit is used for controlling the voltage states of the two enabling pins of the RS485 communication chip according to the output of the switch control unit.
In a second aspect, the application further provides a circuit board, which comprises the RS485 communication circuit provided in the first aspect.
In a third aspect, the present application further provides an industrial control device, which includes the circuit board provided in the second aspect.
According to the scheme, the PWM signal output by the main control module is connected into the RS485 communication circuit through the signal access unit, so that the switch control unit and the optical coupler isolation unit are controlled by the PWM signal, and the control of the switching of the receiving and transmitting modes of the RS485 communication chip is realized. When the equipment is down, the main control module does not output a changed PWM signal but outputs a signal with a fixed level, and the signal is isolated by the input capacitor in the signal access unit and does not enter the next-stage unit module any more, namely the input capacitor is not changed along with the signal, so that the transmission of an incorrect enabling signal is effectively prevented, and the reliability and the stability of the system are maintained.
Drawings
Fig. 1 is a schematic block diagram of an RS485 communication circuit according to an embodiment of the present application;
Fig. 2 is a schematic circuit diagram of a signal access unit according to an embodiment of the present application;
Fig. 3 is a schematic circuit diagram of a switch control unit according to an embodiment of the application;
Fig. 4 is a schematic circuit diagram of an optical coupler isolation unit according to an embodiment of the application;
Fig. 5 is a schematic circuit diagram of an RS485 communication circuit according to an embodiment of the present application.
Detailed Description
Embodiments of the present application will be described in further detail below with reference to the drawings and examples. It should be understood that the particular embodiments described herein are illustrative only and are not limiting of embodiments of the application. It should be further noted that, for convenience of description, only some, but not all structures related to the embodiments of the present application are shown in the drawings, and those skilled in the art will appreciate that any combination of technical features may constitute alternative embodiments as long as the technical features are not contradictory to each other after reading the present specification.
The terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged, as appropriate, such that embodiments of the present application may be implemented in sequences other than those illustrated or described herein, and that the objects identified by "first," "second," etc. are generally of a type, and are not limited to the number of objects, such as the first object may be one or more. Furthermore, in the description and claims, "and/or" means at least one of the connected objects, and the character "/", generally means that the associated object is an "or" relationship. In the description of the present application, "a plurality" means two or more, and "a number" means one or more.
And each industrial control device in the heat pump system is communicated through an RS485 bus, and correspondingly, each industrial control device is correspondingly provided with a corresponding RS485 communication circuit, and communication is carried out in the RS485 communication circuit through an RS485 communication chip. Two enable pins on the RS485 communication chip for controlling the transmission mode or the reception mode are triggered based on signals in different voltage states, for example, the enable pin corresponding to the reception module is valid at a low level, and the enable pin corresponding to the transmission mode is valid at a high level.
When the equipment is down, the enabling pin of the RS485 communication chip may be stopped at a certain fixed level, for example, the enabling pin is at a high level before the down and is at a low level after the down, so that the RS485 communication chip is switched from a receiving mode to a transmitting mode, and the RS485 bus cannot normally exchange data.
Fig. 1 is a schematic block diagram of an RS485 communication circuit according to an embodiment of the present application, where the RS485 communication circuit includes a signal access unit 110, a switch control unit 120, an optocoupler isolation unit 130, and an RS485 communication chip.
The signal access unit 110 is used as a unit module connected with the main control module in the RS485 communication circuit, and is used for accessing the PWM signal output by the main control module through the enable signal transmitting end, that is, the main control module controls the switching of the receiving and transmitting modes of the RS485 communication circuit through the PWM signal in the scheme. The signal access unit 110 performs a dc blocking process on the accessed PWM signal through an input capacitor thereon, that is, uses the dc blocking characteristic of the capacitor, so that the PWM signal retains the ac waveform and removes the dc component.
And the input end of the switch control unit 120 is connected with the output end of the signal access unit 110 to access the PWM signal output by the signal access unit 110, so as to regulate and control the on-off state of the switch control unit based on the voltage change of the PWM signal, thereby realizing switch control and controlling the output of the switch control unit 120.
And the input end of the optocoupler isolation unit 130 is connected with the output end of the switch control unit 120, and the output end of the optocoupler isolation unit 130 is connected with two enable pins of the RS485 communication chip, namely, the optocoupler isolation unit 130 controls the voltage states of the two enable pins of the RS485 communication chip according to the output of the switch control unit 120, so that the control of the switching of the receiving and transmitting modes of the RS485 communication chip is realized.
It can be understood that, the scheme accesses the PWM signal output by the main control module to the RS485 communication circuit through the signal access unit 110, so that the PWM signal is used to control the switch control unit 120 and the optocoupler isolation unit 130, so as to realize the control of the switching of the receiving and transmitting modes of the RS485 communication chip. When the equipment is down, the main control module does not output a changed PWM signal but outputs a signal with a fixed level, and the signal is isolated by the input capacitor in the signal access unit 110 and does not enter the next-stage unit module any more, namely the input capacitor is not changed along with the signal, so that the transmission of an incorrect enabling signal is effectively prevented, and the reliability and the stability of the system are maintained.
Fig. 2 is a schematic circuit diagram of a signal access unit according to an embodiment of the application, where the signal access unit includes a first rectifying diode D1, a second rectifying diode D2, a first current limiting resistor R1, and an input capacitor C1. Specifically, the cathode terminal of the first rectifying diode D1 is connected to the power supply voltage, the anode terminal of the first rectifying diode D1 is connected to the cathode terminal of the second rectifying diode D2, and the anode terminal of the second rectifying diode D2 is grounded; the first end of the first current limiting resistor R1 is connected to the cathode end of the first rectifying diode D1, and the second end of the first current limiting resistor R1 is connected to one end of the input capacitor C1, and the other end of the input capacitor C1 is used as the output end of the signal access unit.
The two diodes are connected in series and are reversely connected into the power supply voltage, so that the connected PWM signal is subjected to voltage clamping, and the voltage amplitude of the PWM signal is clamped. And the PWM signal is connected into the input capacitor C1 through the first current limiting resistor R1, and the direct current component in the PWM signal is isolated through the input capacitor C1, so that an alternating current waveform is generated, and the switch control unit is controlled conveniently.
Therefore, by utilizing the signal access unit, when the main control module works normally, the output PWM signal can still trigger the enabling of the RS485 communication chip, and when the main control module is down or abnormal, the signal access unit can keep the charge state of the main control module through the input capacitor C1 and does not respond to the change of the signal, thereby avoiding the transmission of wrong enabling signals and effectively maintaining the stability of the communication among the devices.
It should be noted that, in some embodiments, a schottky diode may be used instead of the rectifying diode.
In some embodiments, the switch control unit includes an input rectifying sub-unit and an output control sub-unit, wherein an input terminal of the input rectifying sub-unit is connected to an output terminal of the signal access unit, an output terminal of the input rectifying sub-unit is connected to an input terminal of the output control sub-unit, and an output terminal of the output control sub-unit is used as an output terminal of the switch control unit. The input rectifying subunit rectifies the accessed PWM signal, and the output control subunit performs switch control according to the rectified output of the input rectifying subunit.
Specifically, in one embodiment, the input rectifying sub-unit includes a third rectifying diode, a fourth rectifying diode, and a bias resistor. The anode end of the third rectifying diode is connected with the output end of the signal access unit, the cathode end of the third rectifying diode is connected with one end of the bias resistor, and the other end of the bias resistor is grounded; the cathode end of the fourth rectifying diode is connected with the anode end of the third rectifying diode, and the anode end of the fourth rectifying diode is grounded.
It will be appreciated that the incoming PWM signal is rectified by the third rectifier diode and the bias resistor, thereby preserving the signal waveform of the positive half cycle, and that the signal can be clamped again by the fourth rectifier diode with its anode grounded before rectifying the PWM signal.
In one embodiment, the output control subunit includes a second current limiting resistor, a first filter capacitor, an NPN triode, a first voltage dividing resistor, and a second voltage dividing resistor. The first end of the second current limiting resistor is connected with the output end of the input rectifying subunit, and the second end of the second current limiting resistor is connected with the base electrode end of the NPN triode; one end of the first filter capacitor is connected with the first end of the second current-limiting resistor, the other end of the first filter capacitor is connected with the emitter end of the NPN triode, and the emitter end of the NPN triode is grounded; the collector end of the NPN triode is connected with one end of a first voltage dividing resistor, the other end of the first voltage dividing resistor is connected with one end of a second voltage dividing resistor, and the other end of the second voltage dividing resistor is connected with a power supply voltage.
It can be understood that the first filter capacitor is used for filtering the accessed signal, the voltage at the collector end of the NPN triode is obtained by dividing the power supply voltage through the first voltage dividing resistor and the second voltage dividing resistor which are connected in series, the voltage at the base end of the NPN triode corresponds to the rectified signal, and when the voltages at the ends of the NPN triode meet the conduction condition, the NPN triode is conducted, so that the switch control unit is controlled to output to the optocoupler isolation unit.
It should be noted that in some embodiments, the first filter capacitor is an electrolytic capacitor, an anode terminal of the electrolytic capacitor is connected to the first terminal of the second current limiting resistor, and a cathode terminal of the electrolytic capacitor is grounded.
Fig. 3 is a schematic circuit diagram of a switch control unit according to an embodiment of the present application, where an anode terminal of a third rectifying diode D3 is connected to an output terminal of a signal access unit, and a cathode terminal of the third rectifying diode D3 is connected to one end of a bias resistor R2, and the other end of the bias resistor R2 is grounded; the cathode end of the fourth rectifying diode D4 is connected with the anode end of the third rectifying diode D3, and the anode end of the fourth rectifying diode D4 is grounded; the first end of the second current limiting resistor R3 is connected with the cathode end of the third rectifying diode D3, and the second end of the second current limiting resistor R3 is connected with the base end of the NPN triode Q1; one end of the first filter capacitor C2 is connected with the first end of the second current limiting resistor R3, the other end of the first filter capacitor C2 is connected with the emitter end of the NPN triode Q1, and the emitter end of the NPN triode Q1 is grounded; the collector end of the NPN triode Q1 is connected with one end of a first voltage dividing resistor R4, the other end of the first voltage dividing resistor R4 is connected with one end of a second voltage dividing resistor R5, and the other end of the second voltage dividing resistor R5 is connected with a power supply voltage. It can be understood that after the accessed PWM signal is rectified by the third rectifying diode D3 and the bias resistor R2, the rectified signal is accessed to the base terminal of the NPN triode Q1, so as to control the on state of the NPN triode Q1, and further control the on state of the optocoupler isolation unit of the subsequent stage.
Fig. 4 is a schematic circuit diagram of an optocoupler isolation unit according to an embodiment of the application, where the optocoupler isolation unit includes an optocoupler PC1, a third voltage dividing resistor R6, a fourth voltage dividing resistor R7, and a second filter capacitor C3.
Specifically, the input terminal of the photo coupler PC1 is connected to the output terminal of the switch control unit, and it is conceivable that the photo coupler PC1 is equivalent to a combination of a light emitting source (e.g., a light emitting diode) and a light receiving device (e.g., a photodiode or a phototransistor), so that there are two input terminals on the input side of the photo coupler PC1, and in combination with the above embodiment, the two input terminals of the photo coupler PC1 may be connected to two ends of the first voltage dividing resistor, respectively. And the first output end of the photo coupler PC1 is connected with the power supply voltage, the second output end of the photo coupler PC1 is connected with the first end of the third voltage dividing resistor R6, and the second end of the third voltage dividing resistor R6 is grounded.
The first end of the fourth voltage dividing resistor R7 is connected to the first end of the third voltage dividing resistor R6, the second end of the fourth voltage dividing resistor R7 is connected to one end of the second filter capacitor C3, and the other end of the second filter capacitor C3 is grounded. The second end of the fourth voltage dividing resistor R7 is used as an output end of the optical coupler isolation unit, and is connected with two enabling pins of the RS485 communication chip.
It can be understood that whether the light emitting source of the photo coupler PC1 emits light is controlled by the output of the switch control unit, and when the light emitting source emits light, the light receiving source is turned on, and the second output terminal of the photo coupler PC1 outputs a high-level voltage signal, so that the voltage signal is transmitted to the two enable pins of the RS485 communication chip through the fourth voltage dividing resistor R7. Of course, when the light receiving source of the photocoupler PC1 is not turned on, the two enable pins of the RS485 communication chip receive low level signals.
It should be noted that in some embodiments, the photocoupler may be a single-channel photocoupler, or any channel of a multi-channel photocoupler.
Fig. 5 is a schematic circuit diagram of an RS485 communication circuit according to an embodiment of the present application, where in an embodiment, the RS485 communication circuit is connected to a PWM signal output by a main control module through a first current limiting resistor R1, and a first rectifying diode D1 and a second rectifying diode D2 are connected to a first end of the first current limiting resistor R1, a cathode end of the first rectifying diode D1 is connected to a power supply voltage, an anode end of the first rectifying diode D1 is connected to a cathode end of the second rectifying diode D2, and an anode end of the second rectifying diode D2 is grounded; the first end of the first current limiting resistor R1 is connected to the cathode end of the first rectifying diode D1, and the second end of the first current limiting resistor R1 is connected to one end of the input capacitor C1.
The other end of the input capacitor C1 is connected with the anode end of the third rectifying diode D3, the cathode end of the third rectifying diode D3 is connected with one end of the bias resistor R2, and the other end of the bias resistor R2 is grounded; the cathode end of the fourth rectifying diode D4 is connected with the anode end of the third rectifying diode D3, and the anode end of the fourth rectifying diode D4 is grounded; the first end of the second current limiting resistor R3 is connected with the cathode end of the third rectifying diode D3, and the second end of the second current limiting resistor R3 is connected with the base end of the NPN triode Q1; one end of the first filter capacitor C2 is connected with the first end of the second current limiting resistor R3, the other end of the first filter capacitor C2 is connected with the emitter end of the NPN triode Q1, and the emitter end of the NPN triode Q1 is grounded; the collector end of the NPN triode Q1 is connected with one end of a first voltage dividing resistor R4, the other end of the first voltage dividing resistor R4 is connected with one end of a second voltage dividing resistor R5, and the other end of the second voltage dividing resistor R5 is connected with a power supply voltage.
And two input ends of the photo coupler PC1 may be connected to two ends of the first voltage dividing resistor R4, respectively. And the first output end of the photo coupler PC1 is connected with the power supply voltage, the second output end of the photo coupler PC1 is connected with the first end of the third voltage dividing resistor R6, and the second end of the third voltage dividing resistor R6 is grounded. The first end of the fourth voltage dividing resistor R7 is connected to the first end of the third voltage dividing resistor R6, the second end of the fourth voltage dividing resistor R7 is connected to one end of the second filter capacitor C3, and the other end of the second filter capacitor C3 is grounded. The second end of the fourth voltage dividing resistor R7 is also connected with two enabling pins of the RS485 communication chip U1.
It can be understood that the circuit isolates the direct current component from the connected PWM signal through the input capacitor C1 to form an ac waveform PWM signal, so that the PWM signal is rectified through the third rectifying diode D3 and the bias resistor R2, and the rectified signal is further connected to the base terminal of the NPN triode Q1, so as to control the on state of the NPN triode Q1. After the NPN triode Q1 is in the on state, the photo coupler PC1 is also in the on state (i.e. the light emitting source and the light receiving source on the NPN triode Q1 are both on), so as to output high-level voltage signals to the two enable pins of the RS485 communication chip U1. Therefore, the circuit can realize control of switching of the receiving and transmitting modes of the RS485 communication chip U1 by controlling the conducting state of the NPN triode Q1.
Moreover, when the equipment is down and the signal accessed by the circuit is not a PWM signal but a signal with a certain fixed level, the input capacitor C1 cannot follow the change of the signal due to the existence of the input capacitor C1, so that the transmission of an incorrect enabling signal to the RS485 communication chip U1 is effectively prevented.
The embodiment of the application also provides a circuit board which comprises the RS485 communication circuit as in the embodiment and has corresponding functions and beneficial effects. By applying the circuit board, the error enabling signal output by the main control module can not be transmitted to other equipment on the RS485 bus, so that the condition of disordered data receiving and transmitting of the equipment is avoided, and the stable operation of the system is effectively maintained.
The embodiment of the application also provides industrial control equipment, such as a main control board, a frequency conversion board and the like, which comprise the circuit board provided by the embodiment, and have corresponding functions and beneficial effects. Each industrial control equipment in the heat pump system realizes data receiving and transmitting control through the circuit board, and can also avoid transmission of wrong enabling signals when equipment is down, so that the normal operation of data communication among the industrial control equipment in the heat pump system is maintained, and the stable operation of the heat pump system is maintained.
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 one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises an element.
Note that the above is only a preferred embodiment of the present application and the technical principle applied. It will be understood by those skilled in the art that the present application is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the application. Therefore, while the application has been described in connection with the above embodiments, the application is not limited to the embodiments, but may be embodied in many other equivalent forms without departing from the spirit or scope of the application, which is set forth in the following claims.
Claims (10)
1. An RS485 communication circuit, comprising an RS485 communication chip, the circuit further comprising:
The signal access unit comprises an input capacitor, and is used for accessing a PWM signal output by the main control module through the enabling signal transmitting end and performing blocking processing on the PWM signal through the input capacitor;
The input end of the switch control unit is connected with the output end of the signal access unit so as to be accessed to the PWM signal output by the signal access unit, and the switch control unit is used for performing switch control according to the PWM signal;
The input end of the optical coupling isolation unit is connected with the output end of the switch control unit, the output end of the optical coupling isolation unit is connected with two enabling pins of the RS485 communication chip, and the optical coupling isolation unit is used for controlling the voltage states of the two enabling pins of the RS485 communication chip according to the output of the switch control unit.
2. The RS485 communication circuit according to claim 1, wherein the signal access unit comprises a first rectifying diode, a second rectifying diode, a first current limiting resistor and the input capacitance;
The cathode end of the first rectifying diode is connected with a power supply voltage, the anode end of the first rectifying diode is connected with the cathode end of the second rectifying diode, and the anode end of the second rectifying diode is grounded;
The first end of the first current limiting resistor is connected with the anode end of the first rectifying diode and is connected with the PWM signal, and the second end of the first current limiting resistor is connected with one end of the input capacitor.
3. The RS485 communication circuit according to claim 1, wherein the switch control unit comprises an input rectifier subunit and an output control subunit; the input end of the input rectifying subunit is connected with the output end of the signal access unit, and the input rectifying subunit is used for rectifying the PWM signal; the input end of the output control subunit is connected with the output end of the input rectifying subunit, and the output control subunit is used for performing switch control according to the output of the input rectifying subunit.
4. The RS485 communication circuit according to claim 3, wherein the input rectifying sub-unit comprises a third rectifying diode, a fourth rectifying diode and a bias resistor;
The anode end of the third rectifying diode is connected with the output end of the signal access unit, the cathode end of the third rectifying diode is connected with one end of the bias resistor, and the other end of the bias resistor is grounded;
The cathode end of the fourth rectifying diode is connected with the anode end of the third rectifying diode, and the anode end of the fourth rectifying diode is grounded.
5. The RS485 communication circuit according to claim 3 or 4, wherein the output control subunit comprises a second current limiting resistor, a first filter capacitor, an NPN triode, a first voltage dividing resistor and a second voltage dividing resistor;
The first end of the second current limiting resistor is connected with the output end of the input rectifying subunit, and the second end of the second current limiting resistor is connected with the base end of the NPN triode;
One end of the first filter capacitor is connected with the first end of the second current-limiting resistor, the other end of the first filter capacitor is connected with the emitter end of the NPN triode, and the emitter end of the NPN triode is grounded;
The collector end of the NPN triode is connected with one end of the first voltage dividing resistor, the other end of the first voltage dividing resistor is connected with one end of the second voltage dividing resistor, and the other end of the second voltage dividing resistor is connected with a power supply voltage.
6. The RS485 communication circuit according to claim 5, wherein the first filter capacitor is an electrolytic capacitor, the positive terminal of the electrolytic capacitor is connected to the first terminal of the second current limiting resistor, and the negative terminal of the electrolytic capacitor is grounded.
7. The RS485 communication circuit according to claim 1, wherein the optocoupler isolation unit comprises an optocoupler, a third voltage dividing resistor, a fourth voltage dividing resistor and a second filter capacitor;
The input end of the photoelectric coupler is connected with the output end of the switch control unit, the first output end of the photoelectric coupler is connected with a power supply voltage, and the second output end of the photoelectric coupler is connected with the first end of the third voltage dividing resistor;
The first end of the third voltage dividing resistor is connected with the first end of the fourth voltage dividing resistor, and the second end of the fourth voltage dividing resistor is connected with two enabling pins of the RS485 communication chip;
One end of the second filter capacitor is connected with the second end of the fourth voltage dividing resistor, and the other end of the second filter capacitor is connected with the second end of the third voltage dividing resistor and grounded.
8. The RS485 communication circuit according to claim 7, wherein the optocoupler is any channel of a single channel optocoupler or a multi-channel optocoupler.
9. A circuit board, characterized in that the circuit board comprises an RS485 communication circuit according to any of claims 1-8, which circuit board is adapted to receive or transmit data transmitted on an RS485 bus.
10. An industrial control device comprising the wiring board of claim 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322607561.5U CN220823090U (en) | 2023-09-22 | 2023-09-22 | RS485 communication circuit, circuit board and industrial control equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322607561.5U CN220823090U (en) | 2023-09-22 | 2023-09-22 | RS485 communication circuit, circuit board and industrial control equipment |
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| CN220823090U true CN220823090U (en) | 2024-04-19 |
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| CN202322607561.5U Active CN220823090U (en) | 2023-09-22 | 2023-09-22 | RS485 communication circuit, circuit board and industrial control equipment |
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| GR01 | Patent grant |