Interface circuit for RS485 testing

Abstract

The utility model relates to RS485 test technical field discloses an interface circuit for RS485 test, including RS485 interface unit, LED lamp LED3, fuse F1, double -terminal connector P4, adaptive resistance R16, clamping unit, double -terminal connector P2, double -terminal connector P5 and double -terminal connector P6, in use, the utility model discloses whether the two terminals of double -terminal connector P4 can control whether adaptive resistance R16 is accessed between B connecting end and A connecting end through control, makes the circuit adaptation different application scene, secondly, through fuse F1 can carry out overcurrent protection, through LED lamp LED3 can carry out power access display, and the operator is convenient to understand power use situation, in addition, through setting clamping unit can carry out the voltage between B connecting end and A connecting end clamping, carry out overvoltage protection, avoid voltage excessively high damage circuit, finally through setting double -terminal connector P5 and double -terminal connector P6 can provide contact for test, convenient test.

Description

Technical Field

[0001] This utility model relates to the field of RS485 testing technology, and specifically to an interface circuit for RS485 testing. Background Technology

[0002] RS485 bus is widely used in industrial automation and data acquisition due to its advantages such as strong long-distance transmission capability and good multi-node compatibility. In the research and development and production of related RS485 bus devices, key performance indicators such as power consumption and communication capabilities need to be tested to ensure suitability for various scenarios.

[0003] When testing an existing RS485 bus, an RS485 transceiver circuit needs to be connected to the RS485 bus. The following problems arise during testing: Firstly, there is a lack of dedicated sampling points, requiring the communication line to be cut in order to collect relevant electrical parameters, which is a cumbersome operation. Secondly, during testing, there was a lack of overvoltage protection measures. If the external voltage is too high, it may damage the RS485 transceiver circuit. Additionally, RS485 transceiver circuits have limited applicability and cannot be switched according to actual needs. Finally: The lack of overcurrent protection and power input display means that operators cannot intuitively understand the power status. Utility Model Content

[0004] In view of the shortcomings of the prior art, the present invention provides an interface circuit for RS485 testing, which can provide sampling points for RS485 testing and realize overvoltage protection, power supply overcurrent protection, power supply access display and switching of multiple application scenarios.

[0005] To solve the above technical problems, this utility model provides the following technical solution: an interface circuit for RS485 testing, including an RS485 interface unit, an LED lamp LED3, a fuse F1, a two-terminal connector P4, an adapter resistor R16, a clamping unit, a two-terminal connector P2, a two-terminal connector P5, and a two-terminal connector P6. The power supply terminal of the RS485 interface unit is electrically connected to the cathode of the LED lamp LED3, and the anode of the LED lamp LED3 is electrically connected to one end of the fuse F1. The other end of the fuse F1 is used to input the power supply voltage. The B connection terminal of the RS485 interface unit is electrically connected to one connection terminal of the two-terminal connector P4, one connection terminal of the two-terminal connector P6, and one connection terminal of the two-terminal connector P2, respectively. The A connection terminal of the RS485 interface unit is electrically connected to one end of the adapter resistor R16, one connection terminal of the two-terminal connector P5, and the other connection terminal of the two-terminal connector P2, respectively. The other end of the adapter resistor R16 is electrically connected to the other connection terminal of the two-terminal connector P4. The dual-terminal connector P2 is used for electrical connection with the RS485 bus. The clamping unit is electrically connected to both the B connection terminal and the A connection terminal, and is used to clamp the voltage between the B connection terminal and the A connection terminal.

[0006] In one embodiment, the RS485 interface unit includes an RS485 transceiver chip U3 of model number JME8871; pin 8 of the RS485 transceiver chip U3 is the power supply terminal, pin 7 of the RS485 transceiver chip U3 is the B connection terminal, pin 6 of the RS485 transceiver chip U3 is the A connection terminal, pin 5 of the RS485 transceiver chip U3 is grounded, and pins 2 and 3 of the RS485 transceiver chip U3 are electrically connected.

[0007] In one embodiment, the present invention further includes a five-terminal connector P1, three of which are electrically connected to pin 1, pin 2, and pin 4 of the RS485 transceiver chip U3, respectively; the remaining two terminals of the five-terminal connector are used for grounding and inputting the power supply voltage, respectively.

[0008] In one embodiment, the present invention further includes a two-terminal connector P3, wherein the power supply terminal is electrically connected to one connection terminal of the two-terminal connector P3, and the other connection terminal of the two-terminal connector P3 is electrically connected to the cathode of the LED lamp LED3; the other end of the fuse F1 is connected to the power supply voltage through a resistor R3.

[0009] In one embodiment, the clamping unit includes bidirectional TVS diodes FL1, FL2, and FL3; one end of the bidirectional TVS diode FL2 is electrically connected to the B connection terminal and one end of the bidirectional TVS diode FL1, respectively; the other end of the bidirectional TVS diode FL2 is electrically connected to the A connection terminal and one end of the bidirectional TVS diode FL3, respectively; the other end of the bidirectional TVS diode FL1 is grounded, and the other end of the bidirectional TVS diode FL3 is grounded.

[0010] In one embodiment, the other end of the bidirectional TVS diode FL1 is grounded via an LED lamp LED1 and a resistor R2 in sequence.

[0011] In one embodiment, the other end of the bidirectional TVS diode FL3 is grounded via LED lamp LED2 and resistor R1 in sequence.

[0012] In one embodiment, the B connection terminal is electrically connected to one connection terminal of the two-terminal connector P4, one connection terminal of the two-terminal connector P6, and one connection terminal of the two-terminal connector P2 via a resistor R15. The A terminal is electrically connected to one terminal of the two-terminal connector P5 and the other terminal of the two-terminal connector P2 via resistor R17.

[0013] In one embodiment, the other connection terminal of the two-terminal connector P6 is grounded via resistor R14.

[0014] In one embodiment, the other connection terminal of the two-terminal connector P5 receives a power supply voltage through a resistor R18.

[0015] The advantages of this utility model compared with the prior art are: First, by setting up a two-terminal connector P4 and an adapter resistor R16, the connection between the two terminals of the two-terminal connector P4 and the adapter resistor R16 can be controlled by controlling whether the two terminals are connected. This allows the circuit to adapt to different application scenarios. Secondly, a fuse F1 and an LED LED3 are installed at the power supply end of the RS485 interface unit. The fuse F1 can provide overcurrent protection, and the LED LED3 can display the power supply status, making it easy for the operator to understand the power usage. In addition, by setting a clamping unit, the voltage between the B connection terminal and the A connection terminal can be clamped to provide overvoltage protection and prevent the circuit from being damaged by excessive voltage. Finally, by setting up dual-terminal connectors P5 and P6, contact points can be provided for testing, facilitating testing. Attached Figure Description

[0016] Figure 1 This is a circuit diagram of the present invention as shown in the embodiments. Detailed Implementation

[0017] The illustrative embodiments of this application include, but are not limited to, an interface circuit for RS485 testing.

[0018] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0019] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items. Words such as “comprising” or “including” mean that the element or object preceding “comprising” or “including” covers the element or object listed following “comprising” or “including” and its equivalents, and does not exclude other elements or objects. Words such as “connected” or “linked” are not limited to physical or mechanical connections and can include electrical connections, whether direct or indirect.

[0020] like Figure 1 As shown, an interface circuit for RS485 testing includes an RS485 interface unit 1, an LED lamp LED3, a fuse F1, a two-terminal connector P4, an adapter resistor R16, a clamping unit 2, two-terminal connectors P2, P5, and P6. The power supply terminal of RS485 interface unit 1 is electrically connected to the cathode of LED lamp LED3, and the anode of LED lamp LED3 is electrically connected to one end of fuse F1. The other end of fuse F1 is used to input power supply voltage VCC_485. The B connection terminal of RS485 interface unit 1 is electrically connected to one connection terminal of two-terminal connector P4, one connection terminal of two-terminal connector P6 and one connection terminal of two-terminal connector P2 respectively. The A connection terminal of RS485 interface unit 1 is electrically connected to one end of adapter resistor R16, one connection terminal of dual terminal connector P5, and the other connection terminal of dual terminal connector P2, respectively. The other end of adapter resistor R16 is electrically connected to the other connection terminal of dual terminal connector P4. The two-terminal connector P2 is used for electrical connection to the RS485 bus; Clamping unit 2 is electrically connected to connection terminals B and A respectively, and is used to clamp the voltage between connection terminals B and A.

[0021] In practical use, this utility model first sets up a two-terminal connector P4 and an adapter resistor R16. By controlling whether the two terminals of the two-terminal connector P4 are connected, the adapter resistor R16 can be controlled to be connected between the B connection terminal and the A connection terminal. This allows the circuit to adapt to different application scenarios such as long bus communication and short bus communication. In long bus communication, the adapter resistor R16 can be connected to suppress reflection, and in short bus communication, the adapter resistor R16 can be disconnected to reduce power consumption. Secondly, a fuse F1 and an LED LED3 are installed at the power supply end of RS485 interface unit 1. The fuse F1 can provide overcurrent protection, and the LED LED3 can display the power supply status, making it convenient for the operator to understand the power usage. In addition, by setting clamping unit 2, the voltage between connection terminal B and connection terminal A can be clamped to provide overvoltage protection and prevent the circuit from being damaged by excessive voltage. Finally, by setting up dual-terminal connectors P5 and P6, contact points can be provided for testing, facilitating testing.

[0022] Specifically, in this embodiment, the RS485 interface unit 1 includes an RS485 transceiver chip U3 of model JME8871; pin 8 of the RS485 transceiver chip U3 is the power supply terminal, pin 7 of the RS485 transceiver chip U3 is the B connection terminal, pin 6 of the RS485 transceiver chip U3 is the A connection terminal, pin 5 of the RS485 transceiver chip U3 is grounded, and pins 2 and 3 of the RS485 transceiver chip U3 are electrically connected.

[0023] In one implementation, RS485 interface unit 1 can also select other models of RS485 transceiver chips according to actual needs. There is no limitation here. It is only necessary to connect the power supply terminal, A connection terminal and B connection terminal to the other devices according to the above connection relationship.

[0024] In this embodiment, LED3 can emit a green light to indicate the power status. For example, when there is no overcurrent, the fuse F1 does not trip, and LED3 emits a green light to indicate that everything is normal. When an overcurrent occurs and the fuse F1 trips, LED3 does not light up.

[0025] exist Figure 1 In addition, this utility model also includes a five-terminal connector P1, three of which are electrically connected to pin 1, pin 2 and pin 4 of the RS485 transceiver chip U3, respectively; the remaining two terminals of the five-terminal connector are used for grounding and input power supply voltage VCC_485, respectively.

[0026] In practical use, RS485 interface unit 1 can communicate with external devices through five-terminal connector P1 to realize information transmission.

[0027] Specifically, in this embodiment, the present invention also includes a two-terminal connector P3, with the power supply terminal electrically connected to one connection terminal of the two-terminal connector P3, and the other connection terminal of the two-terminal connector P3 electrically connected to the cathode of the LED lamp LED3; the other end of the fuse F1 is connected to the power supply voltage VCC_485 through the resistor R3.

[0028] In actual use, by controlling whether the two connection terminals of the two-terminal connector P3 are connected, it is possible to control whether the power supply voltage VCC_485 is connected to the RS485 interface unit 1.

[0029] Specifically, in this embodiment, in Figure 1 In the clamping unit 2, there are bidirectional TVS diodes FL1, FL2, and FL3. One end of the bidirectional TVS diode FL2 is electrically connected to the B connection terminal and one end of the bidirectional TVS diode FL1, respectively. The other end of the bidirectional TVS diode FL2 is electrically connected to the A connection terminal and one end of the bidirectional TVS diode FL3, respectively. The other end of the bidirectional TVS diode FL1 is grounded, and the other end of the bidirectional TVS diode FL3 is grounded.

[0030] In addition, the other end of the bidirectional TVS diode FL1 is grounded through LED lamp LED1 and resistor R2 in sequence; the other end of the bidirectional TVS diode FL3 is grounded through LED lamp LED2 and resistor R1 in sequence.

[0031] In practical use, when an overvoltage occurs and causes the bidirectional TVS diode FL1 or FL3 to conduct, the LED1 or LED2 will light up as an overvoltage warning, making it easier for the operator to understand the situation. In addition, the LED1 or LED2 can emit a red light for further warning.

[0032] Specifically, in this embodiment, in Figure 1 In the middle, the B connection terminal is electrically connected to one connection terminal of the two-terminal connector P4, one connection terminal of the two-terminal connector P6, and one connection terminal of the two-terminal connector P2 through resistor R15; Terminal A is electrically connected to one terminal of two-terminal connector P5 and the other terminal of two-terminal connector P2 via resistor R17. The other connection terminal of the two-terminal connector P6 is grounded through resistor R14; The other connection terminal of the two-terminal connector P5 receives the power supply voltage VCC_485 through resistor R18; The power supply voltage VCC_485 is also input to one end of capacitor C21, and the other end of capacitor C21 is grounded.

[0033] In practical use, by controlling whether the two terminals of the two-terminal connectors P6 and P5 are connected, the circuit can be adapted to the master and slave positions in RS485 communication; power supply noise can be filtered out through capacitor C21.

[0034] Based on the above description and inspired by this utility model, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. An interface circuit for RS485 testing, characterized in that, Includes RS485 interface unit, LED LED3, fuse F1, two-terminal connector P4, adapter resistor R16, clamping unit, two-terminal connector P2, two-terminal connector P5 and two-terminal connector P6; The power supply terminal of the RS485 interface unit is electrically connected to the cathode of the LED lamp LED3, and the anode of the LED lamp LED3 is electrically connected to one end of the fuse F1. The other end of the fuse F1 is used to input the power supply voltage. The B connection terminal of the RS485 interface unit is electrically connected to one connection terminal of the two-terminal connector P4, one connection terminal of the two-terminal connector P6, and one connection terminal of the two-terminal connector P2, respectively. The A connection terminal of the RS485 interface unit is electrically connected to one end of the adapter resistor R16, one connection terminal of the two-terminal connector P5, and the other connection terminal of the two-terminal connector P2, respectively. The other end of the adapter resistor R16 is electrically connected to the other connection terminal of the two-terminal connector P4. The dual-terminal connector P2 is used for electrical connection with the RS485 bus. The clamping unit is electrically connected to both the B connection terminal and the A connection terminal, and is used to clamp the voltage between the B connection terminal and the A connection terminal.

2. The interface circuit for RS485 testing according to claim 1, characterized in that, The RS485 interface unit includes an RS485 transceiver chip U3 of model JME8871; pin 8 of the RS485 transceiver chip U3 is the power supply terminal, pin 7 of the RS485 transceiver chip U3 is the B connection terminal, pin 6 of the RS485 transceiver chip U3 is the A connection terminal, pin 5 of the RS485 transceiver chip U3 is grounded, and pins 2 and 3 of the RS485 transceiver chip U3 are electrically connected.

3. The interface circuit for RS485 testing according to claim 2, characterized in that, It also includes a five-terminal connector P1, three of which are electrically connected to pins 1, 2, and 4 of the RS485 transceiver chip U3, respectively; the remaining two terminals of the five-terminal connector are used for grounding and inputting the power supply voltage, respectively.

4. The interface circuit for RS485 testing according to claim 1, characterized in that, It also includes a two-terminal connector P3, the power supply terminal is electrically connected to one end of the two-terminal connector P3, and the other end of the two-terminal connector P3 is electrically connected to the cathode of the LED lamp LED3; the other end of the fuse F1 is connected to the power supply voltage through resistor R3.

5. The interface circuit for RS485 testing according to claim 1, characterized in that, The clamping unit includes bidirectional TVS diodes FL1, FL2, and FL3; one end of the bidirectional TVS diode FL2 is electrically connected to the B connection terminal and one end of the bidirectional TVS diode FL1, respectively; the other end of the bidirectional TVS diode FL2 is electrically connected to the A connection terminal and one end of the bidirectional TVS diode FL3, respectively; the other end of the bidirectional TVS diode FL1 is grounded, and the other end of the bidirectional TVS diode FL3 is grounded.

6. The interface circuit for RS485 testing according to claim 5, characterized in that, The other end of the bidirectional TVS diode FL1 is grounded via LED1 and resistor R2.

7. An interface circuit for RS485 testing according to claim 5 or 6, characterized in that, The other end of the bidirectional TVS diode FL3 is grounded via LED2 and resistor R1.

8. The interface circuit for RS485 testing according to claim 1, characterized in that, The B connection terminal is electrically connected to one connection terminal of the two-terminal connector P4, one connection terminal of the two-terminal connector P6, and one connection terminal of the two-terminal connector P2 through resistor R15. The A terminal is electrically connected to one terminal of the two-terminal connector P5 and the other terminal of the two-terminal connector P2 via resistor R17.

9. The interface circuit for RS485 testing according to claim 1, characterized in that, The other connection terminal of the two-terminal connector P6 is grounded through resistor R14; the other connection terminal of the two-terminal connector P5 receives the power supply voltage through resistor R18.

10. An interface circuit for RS485 testing according to claim 1, characterized in that, The power supply voltage is also input to one end of capacitor C21, and the other end of capacitor C21 is grounded.

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