RS485 receiving and transmitting automatic switching isolation circuit
By combining the 485 chip U1 and the transistor Q1, automatic switching between RS485 transmit and receive is achieved, solving the problem of insufficient MCU I/O pins, reducing circuit cost and improving isolation voltage, making it suitable for highly integrated industrial communication circuits.
Patent Information
- Application Number
- CN202423199070.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-24
- Publication Date
- 2025-12-23
- Estimated Expiration
- 2034-12-24
AI Technical Summary
Existing RS485 communication circuits in industrial applications suffer from insufficient MCU I/O pins, resulting in excessive CPU resource consumption, cumbersome steps, and low isolation voltage, making it difficult to meet the requirements of high integration.
The system uses a combination of 485 chip U1 and transistor Q1, and connects to the pins of the isolator through the RO, RE, and DE interfaces. It utilizes NPN transistors and resistors to achieve automatic data transmission and reception switching, saving I/O pins and improving stability. It uses SN75176 chip and B0305XT-1WR2 isolation power supply.
It achieves automatic switching between RS485 transmit and receive, saves I/O pins, reduces circuit cost, and increases the isolation voltage to over 1.5 kV, simplifying circuit design.
Smart Images
Figure CN223713990U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to communication circuit technical field especially relates to a RS485 transceiving automatic switching isolation circuit. BACKGROUND
[0002] 485 communication circuit is widely used in industrial occasions, and has the advantages of strong anti-interference ability, long transmission distance, etc. In the traditional circuit, three signals of CPU are generally required for communication. However, due to the increasing integration and miniaturization trend of electronic circuits, the size of MCU is strictly limited, resulting in insufficient I / O pins. The existing communication circuit occupies one IO port (transmission control pin) of CPU, and the use steps are complicated, and the isolation voltage can only reach 1.5 kV. SUMMARY
[0003] The utility model solves the technical problem that the prior art lacks, provides a RS485 transceiving automatic switching isolation circuit, saves the manufacturing cost, and saves an I / O pin.
[0004] The technical scheme of the utility model is as follows: a RS485 transceiving automatic switching isolation circuit, comprising a 485 chip U1, a RO interface, a RE interface, a DE interface, a DI interface VCC interface and a GND interface are arranged on the 485 chip U1, the sixth pin of the isolator is connected with the RO interface, further comprising a triode, a second resistor is arranged in series on the base of the triode, the other end of the second resistor is connected with the seventh pin of the isolator through the DI interface, the collector of the triode is connected with the RE interface and the DE interface respectively, the collector of the triode is further connected with the first resistor in parallel, the emitter of the triode is connected with the fifth pin of the isolator, the VCC interface is connected with the third resistor in series on the A pin of the 485 chip U1, the fourth resistor is arranged in parallel on the isolation power supply, and the fourth resistor is connected to the B pin of the 485 chip U1.
[0005] From the above scheme, it can be seen that the isolation power supply is used to prevent external, and the utility model saves an I / O pin by the triode combined with the first resistor and the second resistor, and saves the manufacturing cost of the circuit.
[0006] The triode is an NPN triode. Therefore, the triode adopts the NPN triode to improve the stability of operation.
[0007] The 485 chip adopts the chip with model number SN75176.
[0008] The isolation power supply adopts the isolation power supply with model number B0305XT-1WR2.
[0009] The resistance value of the third resistor and the fourth resistor is 4.7KΩ.
[0010] The resistance value of the first resistor and the second resistor is 10KΩ. BRIEF DESCRIPTION OF DRAWINGS
[0011] Figure 1 It is a circuit schematic diagram of the 485 chip;
[0012] Figure 2 It is a circuit schematic diagram of the isolator chip. DETAILED DESCRIPTION
[0013] The technical solutions in the embodiments of the utility model will be clearly and completely described in combination with the drawings in the embodiments of the utility model.
[0014] As shown in the figure, Figure 1 The utility model discloses a kind of RS485 transceiver automatic switching isolation circuits, including 485 chip U1, the 485 chip U1 is equipped with RO interface, RE interface, DE interface, DI interface, VCC interface and GND interface, the RO interface is connected with the sixth pin of isolator G1, still including triode Q1, the base of the triode Q1 is serially connected with second resistance R2, the other end of the second resistance R2 is connected with the seventh pin of isolator G1 by DI interface, the collector of the triode Q1 is connected with the RE interface and the DE interface respectively, the collector of the triode Q1 is also connected with first resistance R1 in parallel, the emitter of the triode Q1 is connected with the fifth pin of isolator G1, the VCC interface is connected on the B pin of the 485 chip U1 in series with third resistance R3, isolation power supply D1 is connected with fourth resistance R4 in parallel, and the fourth resistance R4 is connected to the B pin of the 485 chip U1.
[0015] In the embodiment, pin 2 and pin 3 on the isolator G1 are connected with external single-chip microcomputer respectively for data transmission and data reception, the B pin of the 485 chip U1 and the A pin of the 485 chip U1 are connected with computer or external device, to realize data reception.
[0016] The triode 2 is NPN triode 2, the 485 chip 1 uses chip of model SN75176, the isolation power supply D1 uses isolation power supply of model B0305XT-1WR2, the resistance value of the third resistance R3 and the fourth resistance R4 is 4.7KΩ, the resistance value of the first resistance R1 and the second resistance R2 is 10KΩ.
[0017] The working process of the utility model is: when the external device TXD sends data, the VO1 pin on the isolator G1 outputs high level, the current passes through the resistor R2 to the triode Q1 conduction, the RE / DE pin on the 485 chip U1 is pulled low to low level, at this time the 485 chip U1 automatically switches to the data sending state, the utility model realizes the automatic switching of 485 data receiving or data sending through the resistor R1, the resistor R2 and the triode Q1, saves a CPU pin.
[0018] Finally, it needs to be emphasized that the above description is not used to limit the utility model, for the person skilled in the art, the utility model can have various changes and changes, any modification, equivalent replacement, improvement etc. that is made within the spirit and principle of the utility model should be contained in the protection scope of the utility model.
Claims
1. A RS485 transceiving automatic switching isolation circuit, comprising a 485 chip (U1), wherein a RO interface, a RE interface, a DE interface, a DI interface, a VCC interface and a GND interface are arranged on the 485 chip (U1), and the RO interface is connected with a sixth pin of an isolator (G1), characterized in that: A triode (Q1) is provided with a second resistor (R2) in series at its base, the other end of the second resistor (R2) is connected with the seventh pin of the isolator (G1) through a DI interface, the collector of the triode (Q1) is connected with the RE interface and the DE interface respectively, the collector of the triode (Q1) is further provided with a first resistor (R1) in parallel, the emitter of the triode (Q1) is connected with the fifth pin of the isolator (G1), the VCC interface is connected with the B pin of the 485 chip (U1) in series with a third resistor (R3), the isolation power supply (D1) is provided with a fourth resistor (R4) in parallel, and the fourth resistor (R4) is connected to the A pin of the 485 chip (U1). 2. The RS485 transceiving automatic switching isolation circuit according to claim 1, characterized in that: The triode (Q1) is an NPN triode.
3. The RS485 transceiving automatic switching isolation circuit according to claim 1, characterized in that: The 485 chip adopts a chip with a model number of SN75176.
4. The RS485 transceiving automatic switching isolation circuit according to claim 1, characterized in that: The isolation power supply (D1) adopts an isolation power supply with a model number of B0305XT-1WR2.
5. The RS485 transceiving automatic switching isolation circuit according to claim 1, characterized in that: The resistance values of the third resistor (R3) and the fourth resistor (R4) are 4.7KΩ.
6. The RS485 transceiving automatic switching isolation circuit according to claim 1, characterized in that: The resistance values of the first resistor (R1) and the second resistor (R2) are 10KΩ.