CN219715973U

CN219715973U - Digital isolation type RS485 communication circuit

Info

Publication number: CN219715973U
Application number: CN202320485080.9U
Authority: CN
Inventors: 陈春华; 卢桂喜; 娄满园; 刘增辉; 朱杨杨; 慕田峪; 李雪锋
Original assignee: Xuchang Xuji Checking & Controlling Instrument Co ltd; Henan Senior Electric Co ltd
Current assignee: Xuchang Xuji Checking & Controlling Instrument Co ltd; Henan Senior Electric Co ltd
Priority date: 2023-03-14
Filing date: 2023-03-14
Publication date: 2023-09-19
Anticipated expiration: 2033-03-14

Abstract

The utility model discloses a digital isolation type RS485 communication circuit which comprises a digital isolation chip and a 485 receiving and transmitting controller chip, wherein RXD and TXD signals of a singlechip are output to the 485 receiving and transmitting controller chip in an isolated mode through the digital isolation chip, a serial data port of the digital isolation chip is connected with a data port of the 485 receiving and transmitting controller chip through a transistor Q1, RE and DE ends of the 485 receiving and transmitting controller chip are connected with a collector electrode of the transistor Q1, an emitter electrode of the transistor Q1 is grounded, a TX end of the digital isolation chip is connected with a base electrode of the transistor Q1 through a resistor, and a collector electrode of the transistor Q1 is connected with a power supply through a pull-up resistor R2. The utility model utilizes the static triode Q1 to simultaneously control the output end and the receiving enabling end of the 485 receiving and transmitting control chip, thereby realizing the automatic receiving and transmitting function of RS485 communication.

Description

Digital isolation type RS485 communication circuit

Technical Field

The utility model relates to a communication circuit, in particular to an RS485 communication circuit.

Background

In the power industry and industrial application, RS485 communication is the most common communication mode, and in general, devices and apparatuses directly use RS485 communication, which all require mutual isolation, so as to reduce the risk of damage, and to increase the anti-interference capability. At present, most of schemes use different coils or transformers for isolation of communication power supplies, and use optocouplers for isolation of communication signals, so that an optocoupler is needed for isolation of communication reception and transmission, and because the high-speed optocoupler is expensive and peripheral circuit support is needed for optocoupler control, the increase of the use of the high-speed optocoupler and peripheral circuit devices inevitably causes the increase of circuit cost, and the increase of components also increases circuit fault points, so that the reliability of a communication circuit is objectively reduced; furthermore, the automatic receiving and transmitting function of RS485 communication can not be realized by using the optocoupler isolation.

Disclosure of Invention

Aiming at the defects of the prior art, the utility model provides a digital isolation type RS485 communication circuit, which cancels two high-speed optical couplers and utilizes a digital isolator chip to carry out isolation transmission on communication signals; the output end and the receiving enabling end of the 485 receiving and transmitting chip U2 are controlled simultaneously by utilizing the triode Q1, so that the automatic receiving and transmitting function can be realized through communication.

The utility model adopts the technical scheme that:

the utility model provides a digital isolation formula RS485 communication circuit, includes digital isolation chip and 485 transceiver controller chip, through the digital isolation chip with the RXD of singlechip, TXD signal isolation output to 485 transceiver controller chip on, the serial data port of digital isolation chip passes through transistor Q1 and connects 485 transceiver controller chip's data port, the RE of 485 transceiver controller chip, DE end connect transistor Q1's collecting electrode, transistor Q1's projecting pole ground connection, digital isolation chip's TX end passes through the base of resistor connection triode Q1, transistor Q1's collecting electrode connects the power through pull-up resistor R2 simultaneously.

The data output port A, B of the 485 transceiver controller chip is connected to the output ends TA and TB of the communication circuit through resistors R5 and R6, a TVS tube D3 is connected between the output ends TA and TB, and a TVS tube D2 and a TVS tube D1 are connected between the output ends TA and TB and GND of the communication circuit; the data output port A is connected with a power supply through a pull-up resistor R4, and the data output port B is grounded through a resistor R3.

The digital isolation chip can adopt an integrated circuit chip CA-IS3722HS, the 485 receiving and transmitting controller chip can adopt MAX487E, and the resistance connected with a data output port of the 485 receiving and transmitting controller chip IS 22 ohms.

The utility model has the beneficial effects that:

1. the digital isolation type RS485 communication circuit not only eliminates two expensive high-speed optocouplers, but also reduces peripheral circuit devices controlled by the optocouplers, and communication signals are isolated and transmitted by utilizing a digital isolator chip. The circuit cost is reduced, and the reliability of application is improved.

2. According to the digital isolation type RS485 communication circuit, the output end and the receiving enabling end of the 485 receiving and transmitting chip U2 are controlled simultaneously by the triode Q1, so that the automatic receiving and transmitting function of communication is realized, and a 22 ohm resistor and a TVS tube are added to communication output, so that the anti-interference capability of the communication circuit is ensured.

Drawings

Fig. 1 is a schematic diagram of a digital isolation type RS485 communication circuit according to the utility model.

Detailed Description

In order to make the technical conception and advantages of the utility model to achieve the objects of the utility model more apparent, the technical scheme of the utility model is further described in detail below with reference to the accompanying drawings. It is to be understood that the following examples are provided solely for the purpose of illustrating and describing the preferred embodiments of the present utility model and should not be construed as limiting the scope of the present utility model.

Example 1

Referring to fig. 1, the digital isolation type RS485 communication circuit comprises a digital isolation chip U1 and a 485 receiving and transmitting controller chip, RXD and TXD signals of a singlechip are output to the 485 receiving and transmitting controller chip in an isolated mode through the digital isolation chip U1, a serial data port of the digital isolation chip U1 is connected with a data port of the 485 receiving and transmitting controller chip through a transistor Q1, RE and DE ends of the 485 receiving and transmitting controller chip are connected with a collector electrode of the transistor Q1, an emitter electrode of the transistor Q1 is grounded, a TX end of the digital isolation chip U1 is connected with a base electrode of the transistor Q1 through a resistor, and the collector electrode of the transistor Q1 is simultaneously connected with a power supply through a pull-up resistor R2.

The RXD and TXD signals of the singlechip are isolated and output to a 485 transceiver controller chip through a digital isolation chip U1, and the isolation voltage can reach 5kV, so that the application requirements are completely met; the output end and the receiving enabling end of the 485 receiving and transmitting chip U2 are controlled simultaneously by utilizing the triode Q1, so that the automatic receiving and transmitting function can be realized through communication.

Example 2

Referring to fig. 1, the digitally isolated RS485 communication circuit of the present embodiment is different from embodiment 1 in that: further, a data output port A, B of the 485 transceiver controller chip is connected to output ends TA and TB of the communication circuit through resistors R5 and R6, a TVS tube D3 is connected between the output ends TA and TB, and a TVS tube D2 and a TVS tube D1 are connected between the output ends TA and TB and GND of the communication circuit; the data output port A is connected with a power supply through a pull-up resistor R4, and the data output port B is grounded through a resistor R3. And a 22 ohm resistor and a TVS tube are added to the communication output end of the 485 transceiver controller chip, so that the anti-interference capability of the communication circuit is ensured.

The digital isolation chip can adopt an integrated circuit chip CA-IS3722HS, and the 485 transceiver controller chip can adopt MAX487E, and a person skilled in the art can select the integrated circuit chip with the same function according to technical requirements. The above embodiments are only for illustrating the overall technical concept of the technical solution of the present utility model, and do not limit the present utility model.

Claims

1. The utility model provides a digital isolation formula RS485 communication circuit, includes digital isolation chip and 485 transceiver controller chip, through the digital isolation chip with the RXD of singlechip, TXD signal isolation output to 485 transceiver controller chip on, its characterized in that: the serial data port of the digital isolation chip is connected with the data port of the 485 receiving and transmitting controller chip through the transistor Q1, the RE end and the DE end of the 485 receiving and transmitting controller chip are connected with the collector electrode of the transistor Q1, the emitter electrode of the transistor Q1 is grounded, the TX end of the digital isolation chip is connected with the base electrode of the transistor Q1 through a resistor, and the collector electrode of the transistor Q1 is connected with a power supply through a pull-up resistor R2.

2. The digitally isolated RS485 communications circuit of claim 1, wherein: the data output port A, B of the 485 transceiver controller chip is connected to the output ends TA and TB of the communication circuit through resistors R5 and R6 respectively, a TVS tube D3 is connected between the output ends TA and TB, and a TVS tube D2 and a TVS tube D1 are connected between the output ends TA and TB and the GND of the communication circuit respectively; the data output port A is connected with a power supply through a pull-up resistor R4, and the data output port B is grounded through a resistor R3.

3. The digitally isolated RS485 communication circuit according to claim 1 or 2, wherein: the digital isolation chip adopts an integrated circuit chip CA-IS3722HS, the 485 transceiver controller chip adopts MAX487E, and the resistance value of a resistor R5 and a resistor R6 connected with a data output port A, B of the 485 transceiver controller chip IS 22 ohms.