CN216599612U - Terminal matching resistance switching circuit and RS485 networking communication system - Google Patents
Terminal matching resistance switching circuit and RS485 networking communication system Download PDFInfo
- Publication number
- CN216599612U CN216599612U CN202123200802.1U CN202123200802U CN216599612U CN 216599612 U CN216599612 U CN 216599612U CN 202123200802 U CN202123200802 U CN 202123200802U CN 216599612 U CN216599612 U CN 216599612U
- Authority
- CN
- China
- Prior art keywords
- terminal
- circuit
- switch
- switch circuit
- resistor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Dc Digital Transmission (AREA)
Abstract
The utility model discloses a terminal matching resistance switching circuit and an RS485 networking communication system, wherein the terminal matching resistance switching circuit comprises: the terminal matching resistor, the first switch circuit and the second switch circuit; the first end of the terminal matching resistor is connected with the first end of the RS485 transceiver, and the second end of the terminal matching resistor is respectively connected with the first end of the first switch circuit and the first end of the second switch circuit; the second end of the first switch circuit and the second end of the second switch circuit are respectively connected with the second end of the RS485 transceiver; the controlled ends of the first switch circuit and the second switch circuit are respectively connected with the control signal input end so as to receive a conducting signal or a disconnecting signal; the RS485 transceiver is used for receiving a switching-on signal and controlling the terminal matching resistor to be continuously switched on with the first end and the second end of the RS485 transceiver in turn; and when the disconnection signal is received, the control terminal matching resistor is disconnected with the path of the RS485 transceiver. The utility model saves a large amount of labor cost and improves the convenience of the application of the terminal matching resistor.
Description
Technical Field
The utility model relates to the technical field of communication, in particular to a terminal matching resistance switching circuit and an RS485 networking communication system.
Background
The RS485 bus is widely applied due to the characteristics of simple interface, convenient networking, long transmission distance and the like.
In the RS485 networking communication system, if the transmission distance is long and the transmission rate is high, matching resistors need to be added at the beginning and the end of the bus cable in order to avoid signal reflection and echo. Generally, a matching resistor is externally connected to an interface of the RS485 network, but the matching resistor of the external terminal of a lead wire at the interface needs manual wiring when being applied, so that the labor cost is high, and an external device is easy to lose and poor in contact.
SUMMERY OF THE UTILITY MODEL
The utility model mainly aims to provide a terminal matching resistor switching circuit and an RS485 networking communication system, and aims to solve the problems that a terminal matching resistor of an RS485 network needs to be connected externally manually, and the labor cost is high.
In order to achieve the above object, the present invention provides a terminal matching resistance switching circuit, including: the terminal matching resistor, the first switch circuit and the second switch circuit; the first end of the terminal matching resistor is connected with the first end of the RS485 transceiver; the second end of the terminal matching resistor is respectively connected with the first end of the first switch circuit and the first end of the second switch circuit; the second end of the first switch circuit and the second end of the second switch circuit are respectively connected with the second end of the RS485 transceiver; the controlled end of the first switch circuit and the controlled end of the second switch circuit are respectively connected with a control signal input end so as to receive a conducting signal or a disconnecting signal;
the first switch circuit and the second switch circuit are used for conducting in turn when the conducting signal is received so as to control the terminal matching resistor to be continuously conducted with the first end and the second end of the RS485 transceiver; and when the disconnection signal is received, the terminal matching resistor is controlled to be disconnected with the path of the RS485 transceiver.
Optionally, the first switching circuit comprises a first switching tube; the input end of the first switch tube is the first end of the first switch circuit, the output end of the first switch tube is the output end of the first switch circuit, and the controlled end of the first switch circuit is the controlled end of the first switch circuit.
Optionally, the first switch tube is an NPN transistor, wherein a base of the NPN transistor is a controlled terminal of the first switch tube, a collector of the NPN transistor is an input terminal of the first switch tube, and an emitter of the NPN transistor is an output terminal of the first switch tube.
Optionally, the second switching circuit comprises an inverter and a second switching tube; the input end of the phase inverter is the controlled end of the second switch circuit, the output end of the phase inverter is connected with the controlled end of the second switch circuit, the input end of the second switch tube is the first end of the second switch circuit, and the output end of the second switch tube is the second end of the second switch circuit.
Optionally, the second switch tube is a PNP type transistor, wherein a base of the PNP type transistor is a controlled terminal of the second switch tube, an emitter of the PNP type transistor is an input terminal of the second switch tube, and a collector of the PNP type transistor is an output terminal of the second switch tube.
Optionally, the terminal matching resistance switching circuit further includes a filter circuit; the input end of the filter circuit is connected with the control signal input end, and the output end of the filter circuit is respectively connected with the controlled end of the first switch circuit and the controlled end of the second switch circuit;
the filter circuit is used for filtering the on signal and the off signal.
Optionally, the terminal matching resistance comprises a first terminal resistance and a second terminal resistance; the terminal matching resistance switching circuit further comprises a first capacitor; the first end of the first terminal resistor is the first end of the terminal matching resistor, the second end of the first terminal resistor is connected with the first end of the second terminal resistor, and the second end of the second terminal resistor is the second end of the terminal matching resistor; and the common end of the first terminal resistor connected with the second terminal resistor is connected with the first end of the first capacitor, and the second end of the first capacitor is grounded.
Optionally, the terminal matching resistance switching circuit further comprises a pull-up circuit; and the first end of the pull-up circuit is respectively connected with the controlled end of the first switch circuit and the controlled end of the second switch circuit, and the second end of the pull-up circuit is connected with the input end of the control power supply.
Optionally, the terminal matching resistance switching circuit further includes a pull-down circuit, a first end of the pull-down circuit is connected to the controlled end of the first switch circuit and the controlled end of the second switch circuit, respectively, and a second end of the pull-down circuit is grounded.
In addition, in order to achieve the above object, the present invention further provides an RS485 networking communication system, including the terminal matching resistance switching circuit as described above.
According to the utility model, by arranging the first switch circuit and the second switch circuit, when the transmission distance is long and the transmission speed is high, the terminal matching resistor needs to be accessed in the communication system, the controller of the communication system outputs a conducting signal to control the first switch circuit and the second switch circuit to be conducted in turn, so that the terminal matching resistor is continuously conducted with the first end and the second end of the RS485 transceiver; when the terminal matching resistor is connected in a short-distance and low-speed transmission mode, the terminal matching resistor can be disconnected, the controller outputs a disconnection signal at the moment, and the first switch circuit and the second switch circuit are disconnected, so that the terminal matching resistor is disconnected. Therefore, the connection state of the terminal matching resistor is switched by the controller, manual wiring is not needed, and a large amount of labor cost is saved. And the terminal matching resistor is integrated in the circuit, so that the problem of device loss can be avoided, poor contact is not easy to generate, and the convenience of application is greatly improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings 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 schematic diagram of the wiring of a matching resistor of an RS485 communication terminal in the prior art;
FIG. 2 is a functional block diagram of a terminal matching resistance switching circuit according to an embodiment of the present invention;
FIG. 3 is a schematic circuit diagram of the embodiment of FIG. 2;
FIG. 4 is a schematic diagram of an equivalent circuit of the embodiment of FIG. 2 when a disconnect signal is received;
fig. 5 is a schematic diagram of waveforms on a bus during RS485 communication according to an embodiment of the terminal matching resistor switching circuit of the present invention;
FIG. 6 is a schematic diagram illustrating a current flow when the embodiment of FIG. 3 receives the ON signal;
FIG. 7 is a schematic diagram of an equivalent circuit of the embodiment of FIG. 6;
FIG. 8 is another current flow diagram illustrating the embodiment of FIG. 3 when a turn-on signal is received;
FIG. 9 is a schematic diagram of an equivalent circuit of the embodiment of FIG. 8;
fig. 10 is a circuit diagram of another embodiment of the termination matching resistance switching circuit according to the present invention.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
The reference numbers illustrate:
| reference numerals | Name (R) | Reference numerals | Name (R) |
| 100 | Terminal matching resistance switching circuit | D | Inverter with a capacitor having a |
| 200 | RS485 transceiver | R1 | A |
| 300 | Controller | R2 | |
| 10 | Terminal matching resistor | R3 | |
| 20 | First switch circuit | R4 | Pull- |
| 30 | Second switch circuit | R5 | Pull-down resistor |
| Q1 | First switch tube | C1 | First capacitor |
| Q2 | Second switch tube | C2 | Second capacitor |
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the utility model and are not intended to limit the utility model.
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, 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 invention.
It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, the descriptions related to "first", "second", etc. in the present invention are for descriptive purposes only and are 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, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
Referring to fig. 1, in an RS485 networking communication system, in order to avoid signal reflection and echo, matching resistors are added at the beginning and the end of a bus cable, and the matching resistors take 120 Ω in an RS485 network.
The existing terminal matching resistor access circuit mainly has the following modes: in the mode 1, a lead wire at an interface is externally connected with a matching resistor, and when the matching resistor needs to be connected, manual wiring is needed; mode 2, in the circuit board with the built-in matching resistor, the access circuit is switched through a physical switch (dial, jumper and the like); mode 3, in the matching resistor built-in circuit board, the access circuit is switched by controlling a relay (equivalently controlled physical switch).
However, both of these approaches have significant disadvantages: the mode 1 is not convenient in application, manual wiring is needed, and an external device is easy to lose and has poor contact; mode 2 requires the physical switch to be exposed, which reduces the protection performance for some equipment requiring high protection; when devices at two ends of the RS485 network are far away (sometimes, the distance is thousands of meters), manual dial-up debugging is inconvenient; the relay in the mode 3 occupies a large area of the circuit board and has high cost.
In view of the above problem, the present invention provides a terminal matching resistance switching circuit, and referring to fig. 2, in an embodiment, the terminal matching resistance switching circuit 100 includes:
a terminal matching resistor 10, a first switching circuit 20 and a second switching circuit 30; the first end of the terminal matching resistor 10 is connected with the first end of the RS485 transceiver 200; a second end of the terminal matching resistor 10 is connected to a first end of the first switch circuit 20 and a first end of the second switch circuit 30 respectively; a second end of the first switch circuit 20 and a second end of the second switch circuit 20 are respectively connected with a second end of the RS485 transceiver 200; the controlled end of the first switch circuit 20 and the controlled end of the second switch circuit 30 are respectively connected to a control signal input end to receive a turn-on signal or a turn-off signal;
the first switch circuit 20 and the second switch circuit 30 are configured to be turned on in turn when receiving the turn-on signal, so as to control the terminal matching resistor 10 to be continuously turned on with the first end and the second end of the RS485 transceiver; and when the disconnection signal is received, controlling the terminal matching resistor 10 to be disconnected from the RS485 transceiver 200.
The terminal matching resistor switching circuit 100 may be disposed in an RS485 networking communication system that needs to switch the connection state of the terminal matching resistor according to an actual situation; the RS485 transceiver 200 may communicate with a controller 300 in a communication system, and the controller 300 may be a logic controller such as a microcontroller MCU. The first end and the second end of the RS485 transceiver 200 are respectively a positive end and a negative end of the RS485 transceiver 200, and specifically, which end is the positive end or the negative end can be set according to an actual circuit, which is not limited herein.
The on signal or the off signal is output by the controller 300, and the on signal and the off signal may be high level or low level, respectively, and also need to be set according to an actual circuit. The control signal input terminal may be a control signal output terminal of the controller 300, and may be an input/output interface, for example, which may be set as required.
In this embodiment, the controller 300 in the communication system may receive an external control signal to output an on signal or an off signal; when the conduction signal is output, the first switch circuit 20 and the second switch circuit 30 are alternately conducted according to the received conduction signal, so that the terminal matching resistor 10 and the first end and the second end of the RS485 transceiver 200 are continuously conducted, that is, the terminal matching resistor 10 is continuously connected in the circuit; when the controller 300 outputs the disconnection signal, both the first switch circuit and the second switch circuit are disconnected, so that the connection between the terminal matching resistor and the RS485 transceiver 200 is disconnected.
According to the scheme, the first switch circuit and the second switch circuit are arranged, so that when the transmission distance is long, the baud rate is high, and the terminal matching resistor needs to be accessed into the circuit, the controller of the communication system outputs a conducting signal, the first switch circuit and the second switch circuit are conducted in turn, and the terminal matching resistor is continuously conducted with the first end and the second end of the RS485 transceiver; when the terminal is in low-speed transmission, the terminal matching resistor can not be accessed, at the moment, the controller outputs a disconnection signal, and the first switch circuit and the second switch circuit are both disconnected, so that the terminal matching resistor is disconnected. Therefore, the connection state of the terminal matching resistor is switched by the controller, manual wiring is not needed, and a large amount of labor cost is saved. And the terminal matching resistor is integrated in the circuit, so that the problem of device loss can not occur any more, and the phenomenon of poor contact is not easy to generate. And compared with a mode of switching a physical switch, the convenience of switching the terminal matching resistor is greatly improved.
Further, referring to fig. 3, the first switch circuit 20 includes a first switch tube Q1; the input end of the first switch tube Q1 is the first end of the first switch circuit 20, the output end is the output end of the first switch circuit 20, and the controlled end is the controlled end of the first switch circuit 20.
The first switch tube Q1 can be replaced by an equivalent circuit or a separate electronic component, which is not described herein. Further, the type of the first switch Q1 can also be set according to actual needs, such as a transistor, a field effect transistor, etc.
Further, the first switch Q1 may be an NPN transistor, wherein a base B of the NPN transistor is a controlled terminal of the first switch Q1, a collector C of the NPN transistor is an input terminal of the first switch Q1, and an emitter E of the NPN transistor is an output terminal of the first switch Q1.
Further, the second switch circuit 30 includes an inverter D and a second switch tube Q2; the input end a of the phase inverter D is the controlled end of the second switch circuit 30, the output end Y of the phase inverter D is connected to the controlled end of the second switch circuit 30, the input end of the second switch tube Q2 is the first end of the second switch circuit 30, and the output end of the second switch tube Q2 is the second end of the second switch circuit.
As can be understood, when the input terminal a of the inverter D receives the on signal, the output terminal Y thereof will output an off signal to the second switch Q2; therefore, the states of the first switch tube Q1 and the second switch tube Q2 are opposite, and one is turned on and the other is turned off.
Further, the second switch tube Q2 is a PNP transistor, wherein the base B of the PNP transistor is the controlled terminal of the second switch tube Q2, the emitter E of the PNP transistor is the input terminal of the second switch tube Q2, and the collector C of the PNP transistor is the output terminal of the second switch tube Q2.
It should be noted that the first switch Q1 may also be configured as a PNP transistor, and the second switch Q2 is an NPN transistor; as long as one of the transistors is turned on and the other is turned off upon receiving an on signal or an off signal.
Based on the above hardware structure, the process of switching by the terminal matching resistance switching circuit 100 may be:
the low level of the control signal Ctrl output by the controller 300 is set as an off signal, and the high level is set as an on signal.
When the controller 300 outputs a turn-off signal, the voltage Vbe between the base and the emitter of the first switching tube Q1 is not greater than 0V, the Vbe of the second switching tube Q2 is not less than 0V, both the switching tubes are in a cut-off state, current cannot flow through the circuit, the circuit can be equivalent to fig. 4, and the terminal matching resistor 10 is not switched into the circuit.
When the output of the controller 300 is turned on, the first switch Q1 and the second switch Q2 are turned on at two different times. Referring to fig. 5, when the RS485+ level is a high level VCC (the value of VCC may be set according to an actual circuit, for example, 5V), at this time, the corresponding RS 485-is 0V, Vbe of the first switching tube Q1 is greater than the turn-on voltage, the first switching tube Q1 is turned on, the current in the terminal matching resistor 10 flows to the terminal matching resistor 10 as shown in fig. 6, and the corresponding equivalent circuit is shown in fig. 7, which is equivalent to the terminal matching resistor 10 switching into the system. As shown in the waveforms of fig. 5, when the RS485+ level is 0, at this time, the corresponding RS 485-level is VCC, Veb of the second switch tube Q2 is greater than the conduction voltage, the second switch tube Q2 is turned on, the current in the terminal matching resistor 10 flows as shown in fig. 8, the corresponding equivalent circuit is as shown in fig. 9, and equivalently, the terminal matching resistor 10 is switched into the system. In actual work, the two situations are combined, equivalent circuits are consistent, and the equivalent circuits are both connected to the RS485 circuit access terminal matching resistor 10.
In summary, based on the above hardware structure, the switching of the connection state of the terminal matching resistor 10 is realized by using only two inverters and one inverter, and the total cost of the three devices is lower than the cost of the dial, the jumper, the relay and the like of the physical structure; the occupied area in the circuit board is smaller than or equal to the dial and the jumper, and is much smaller than that of a relay; the control circuit is enabled through communication or software, so that the control is convenient and the use is flexible.
Further, the terminal matching resistance switching circuit 100 further includes a filter circuit 40; the input end of the filter circuit 40 is connected to the control signal input end, and the output end is respectively connected to the controlled end of the first switch circuit 20 and the controlled end of the second switch circuit 30;
the filter circuit 40 is configured to filter the on signal and the off signal.
The structure of the filter circuit 40 may be set according to actual requirements, for example, the filter circuit 40 may include a first resistor R1 and a first capacitor C1; a first end of the first resistor R1 is an input end of the filter circuit 40, a second end of the first resistor R1 is connected to a first end of the first capacitor C1, a second end of the first capacitor C1 is grounded, and a common end of the first resistor R1 and the first capacitor C1 is an output end of the filter circuit 40. By providing the filter circuit 40, the influence of the disturbance on the circuit state can be reduced.
Further, the structure of the terminal matching resistor 10 may also be set according to actual needs, for example, including a first terminal resistor R2 and a second terminal resistor R3; the terminal matching resistance switching circuit 100 further includes a first capacitor C2; a first end of the first termination resistor R2 is a first end of the termination matching resistor 10, a second end of the first termination resistor R2 is connected to a first end of the second termination resistor R3, and a second end of the second termination resistor R2 is a second end of the termination matching resistor 10; the common terminal of the first terminal resistor R2 and the second terminal resistor R3 is connected to the first terminal of the first capacitor C2, and the second terminal of the first capacitor C2 is grounded.
Specifically, the resistances of the first terminal resistor R2 and the second terminal resistor R3 may be set to 60 Ω, and the first capacitor C2 is a filter capacitor, so as to reduce the influence of external interference on the circuit state.
Further, the terminal matching resistance switching circuit 100 further includes a pull-up circuit 50; a first end of the pull-up circuit 50 is connected to the controlled end of the first switch circuit 20 and the controlled end of the second switch circuit 30, respectively, and a second end of the pull-up circuit 50 is connected to the control power input end.
The control power supply input end is used for being connected with a control power supply, and the control power supply can be set according to an actual circuit. By providing the pull-up circuit 50, the default states of the first switch circuit 20 and the second switch circuit 30 during power-up can be controlled. Specifically, when the device is powered on, if the controller 100 does not output the corresponding control signal after the device is powered on, the states of the first switch Q1 and the second switch Q2 may not be satisfactory, for example, misconduction; at this time, the pull-up action of the pull-up circuit 50 can make the first switch tube Q1 and the second switch tube Q2 in a default state as expected. The pull-up circuit 50 may include a pull-up resistor R4, and the pull-up resistor R4 may be a single resistor or a series connection of a plurality of resistors.
Further, the terminal matching resistance switching circuit 100 includes a pull-down circuit 60, a first end of the pull-down circuit 60 is connected to the controlled end of the first switch circuit 20 and the controlled end of the second switch circuit 30, respectively, and a second end of the pull-down circuit 60 is grounded.
The setting of the pull-up circuit 60 may also control the default state of the first switch circuit 20 and the second switch circuit 30. Pull-up circuit 60 may include, among other things, pull-down resistor R5.
The utility model also provides an RS485 networking communication system, which comprises a terminal matching resistance switching circuit, and the structure of the terminal matching resistance switching circuit can refer to the embodiment and is not described herein again. It should be noted that, since the RS485 networking communication system of this embodiment adopts the technical scheme of the terminal matching resistance switching circuit, the RS485 networking communication system has all the beneficial effects of the terminal matching resistance switching circuit.
The above description is only an alternative embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. A termination-matched resistance switching circuit, comprising: the terminal matching resistor, the first switch circuit and the second switch circuit; the first end of the terminal matching resistor is connected with the first end of the RS485 transceiver; the second end of the terminal matching resistor is respectively connected with the first end of the first switch circuit and the first end of the second switch circuit; the second end of the first switch circuit and the second end of the second switch circuit are respectively connected with the second end of the RS485 transceiver; the controlled end of the first switch circuit and the controlled end of the second switch circuit are respectively connected with a control signal input end so as to receive a conducting signal or a disconnecting signal;
the first switch circuit and the second switch circuit are used for conducting in turn when the conducting signal is received so as to control the terminal matching resistor to be continuously conducted with the first end and the second end of the RS485 transceiver; and when the disconnection signal is received, the terminal matching resistor is controlled to be disconnected with the path of the RS485 transceiver.
2. The terminal-matched resistance switching circuit as claimed in claim 1, wherein the first switching circuit includes a first switching tube; the input end of the first switch tube is the first end of the first switch circuit, the output end of the first switch tube is the output end of the first switch circuit, and the controlled end of the first switch circuit is the controlled end of the first switch circuit.
3. The terminal-matched resistance switching circuit as claimed in claim 2, wherein the first switch transistor is an NPN transistor, wherein a base of the NPN transistor is a controlled terminal of the first switch transistor, a collector of the NPN transistor is an input terminal of the first switch transistor, and an emitter of the NPN transistor is an output terminal of the first switch transistor.
4. The terminal-matched resistance switching circuit as claimed in claim 1, wherein the second switching circuit includes an inverter and a second switching tube; the input end of the phase inverter is the controlled end of the second switch circuit, the output end of the phase inverter is connected with the controlled end of the second switch circuit, the input end of the second switch tube is the first end of the second switch circuit, and the output end of the second switch tube is the second end of the second switch circuit.
5. The terminal-matched resistance switching circuit as claimed in claim 4, wherein the second switch tube is a PNP transistor, wherein a base of the PNP transistor is a controlled terminal of the second switch tube, an emitter of the PNP transistor is an input terminal of the second switch tube, and a collector of the PNP transistor is an output terminal of the second switch tube.
6. The terminal matched resistance switching circuit as claimed in claim 1, wherein said terminal matched resistance switching circuit further comprises a filter circuit; the input end of the filter circuit is connected with the control signal input end, and the output end of the filter circuit is respectively connected with the controlled end of the first switch circuit and the controlled end of the second switch circuit;
the filter circuit is used for filtering the on signal and the off signal.
7. The terminal-matched resistance switching circuit as claimed in claim 1, wherein said terminal-matched resistance includes a first terminal resistance and a second terminal resistance; the terminal matching resistance switching circuit further comprises a first capacitor; the first end of the first terminal resistor is the first end of the terminal matching resistor, the second end of the first terminal resistor is connected with the first end of the second terminal resistor, and the second end of the second terminal resistor is the second end of the terminal matching resistor; and the common end of the first terminal resistor connected with the second terminal resistor is connected with the first end of the first capacitor, and the second end of the first capacitor is grounded.
8. The terminal matching resistance switching circuit according to any one of claims 1 to 7, wherein the terminal matching resistance switching circuit further comprises a pull-up circuit; and the first end of the pull-up circuit is respectively connected with the controlled end of the first switch circuit and the controlled end of the second switch circuit, and the second end of the pull-up circuit is connected with the input end of the control power supply.
9. The terminal matching resistance switching circuit according to any one of claims 1 to 7, further comprising a pull-down circuit, a first terminal of the pull-down circuit being connected to the controlled terminal of the first switch circuit and the controlled terminal of the second switch circuit, respectively, and a second terminal of the pull-down circuit being connected to ground.
10. An RS485 networking communication system, comprising the terminal matching resistance switching circuit according to any of claims 1-9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123200802.1U CN216599612U (en) | 2021-12-16 | 2021-12-16 | Terminal matching resistance switching circuit and RS485 networking communication system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123200802.1U CN216599612U (en) | 2021-12-16 | 2021-12-16 | Terminal matching resistance switching circuit and RS485 networking communication system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN216599612U true CN216599612U (en) | 2022-05-24 |
Family
ID=81615774
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202123200802.1U Active CN216599612U (en) | 2021-12-16 | 2021-12-16 | Terminal matching resistance switching circuit and RS485 networking communication system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN216599612U (en) |
-
2021
- 2021-12-16 CN CN202123200802.1U patent/CN216599612U/en active Active
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107395243B (en) | Single-wire communication circuit | |
| CN112886813A (en) | MBUS host sending circuit, bus system and signal sending method | |
| CN216599612U (en) | Terminal matching resistance switching circuit and RS485 networking communication system | |
| CN113422599A (en) | RS485 automatic receiving and transmitting control device and communication equipment | |
| CN112346403A (en) | Extend module connecting circuit | |
| CN215268318U (en) | CAN bus resistance matching circuit | |
| CN210112034U (en) | CAN transceiver circuit and CAN communication system | |
| CN207896965U (en) | RS485 circuits and communication system | |
| CN213426160U (en) | Single-wire communication conversion circuit, single-wire communication device and equipment | |
| CN206835123U (en) | A kind of RS485 automatic receiving-transmitting switching circuits | |
| CN113411241A (en) | RS485 communication circuit, communication system and air conditioning system | |
| CN214480279U (en) | MBUS host sending circuit and MBUS bus system | |
| CN215930026U (en) | Communication circuit of air conditioning system, indoor unit, outdoor unit and air conditioning system | |
| CN209913795U (en) | Wake-up circuit and electronic equipment | |
| CN109960677B (en) | Extension circuit for USB interface | |
| CN111976415B (en) | Outdoor unit electric control device and vehicle-mounted air conditioner | |
| CN204576183U (en) | Multi-purpose CAN bus terminal resistor access device | |
| CN209488551U (en) | A kind of signal input circuit of NPN signal and PNP signal compatibility | |
| CN217037179U (en) | Communication circuit and communication board | |
| CN211928417U (en) | Novel high-reliability isolation single-wire level conversion communication circuit | |
| CN216596238U (en) | Interface reversing circuit and electronic equipment | |
| CN217157120U (en) | Communication circuit and communication chip | |
| CN221328935U (en) | Reset circuit with voltage hysteresis function | |
| CN216817396U (en) | Conversion circuit for converting four-wire system TTL interface into two-wire system bus interface | |
| CN216751748U (en) | Terminal resistor access control circuit, communication circuit and communication equipment |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |