CN215867844U

CN215867844U - Serial port communication isolation circuit

Info

Publication number: CN215867844U
Application number: CN202121656351.XU
Authority: CN
Inventors: 吕正文; 李娜; 曹双喜
Original assignee: Jiangsu Ocpt Institute Co ltd
Current assignee: Jiangsu Ocpt Institute Co ltd
Priority date: 2021-07-20
Filing date: 2021-07-20
Publication date: 2022-02-18
Anticipated expiration: 2031-07-20

Abstract

The utility model relates to the technical field of serial port communication, in particular to a serial port communication isolation circuit which comprises a gating and dialing device, a first serial port transceiver, a second serial port transceiver and a data interface connector, wherein the gating and dialing device, the first serial port transceiver, the second serial port transceiver and the data interface connector are sequentially connected with a first digital isolator, an MCU serial port communication signal passes through the first digital isolator and then is connected with the gating and dialing device, and the gating and dialing device selects to transmit the MCU serial port communication signal to the first serial port transceiver or the second serial port transceiver and then is connected with an external upper computer through the data interface connector. The utility model solves the problem that a single interface is compatible with various industrial bus protocols and is converted into a universal serial communication protocol which can be identified by a microcontroller, and a user selects different communication modes, thereby avoiding serious accidents caused by artificial misoperation and wrong setting.

Description

Serial port communication isolation circuit

Technical Field

The utility model relates to the technical field of serial port communication, in particular to a serial port communication isolation circuit.

Background

With the continuous development of the technology in the industrial control field in China, industrial bus signals become an indispensable way for communication between industrial devices. For various industrial bus protocols, such as RS232 and RS485, one device may have multiple industrial bus protocols, or the industrial bus protocols of multiple devices are different from each other, and when a user connects a control end to these controlled devices, the user often needs to pay attention to distinguish the connections of different industrial bus protocols to avoid connecting different bus protocols together. There is a need for a circuit that is compatible with multiple industrial bus protocols in the form of a single interface, and converts the interface into a universal serial communication protocol that can be recognized by a microcontroller, so that a user can select different communication modes when using the circuit, and major accidents caused by manual misoperation and wrong setting can be avoided.

SUMMERY OF THE UTILITY MODEL

In order to overcome the problems in the related art, the disclosed embodiment of the utility model provides a serial port communication isolation circuit. The technical scheme is as follows:

a serial port communication isolation circuit comprises: the second pin and the third pin of the first digital isolator are receiving and transmitting ports of an external MCU, the sixth pin and the seventh pin of the first digital isolator are respectively connected with the fourth pin and the third pin of the strobe dialer, the first pin and the second pin of the strobe dialer are respectively connected with the twelfth pin and the eleventh pin of the first serial transceiver, the fifth pin and the sixth pin of the strobe dialer are respectively connected with the first pin and the fourth pin of the second serial transceiver, and the thirteenth pin and the fourteenth pin of the first serial transceiver are connected with the second pin and the third pin of the data interface connector; a sixth pin and a seventh pin of the second serial port transceiver are connected with a resistor R7 in parallel and then are connected with a seventh pin and an eighth pin of the data interface connector; the data interface connector is connected with an external upper computer.

The third pin of the second digital isolator is an external MCU (microprogrammed control unit) transceiving integrated port, and the sixth pin of the second digital isolator is connected with the second pin and the third pin of the second serial transceiver;

due to the fact that the RS232 single-end receives and transmits, the common mode interference resistance is poor, interference is easy to generate, the data transmission rate is low, and the transmission distance is short. In order to realize direct connection at a longer distance and a higher speed, the third pin of the digital isolator U9 adopts an RS485 bus, and the RS485 bus adopts a data transceiver with balanced transmission and differential reception to drive the bus, that is, the differential signal a transmits transmission data first, and the differential signal B transmits reception data, unlike the RS232 which is an independent RXD and TXD.

Further, the model of the first serial transceiver chip is MAX3232, and the model of the second serial transceiver chip is MAX 485.

The utility model has the beneficial effects that:

1. one port is flexibly gated and compatible with two communication modes, and the two communication modes are executed in a functional mode, so that the authority modes of maintainers and users are distinguished while the expandability is strong.

Drawings

Fig. 1 is a circuit diagram of a serial communication isolation circuit according to the present invention.

Detailed Description

The present invention will now be described in further detail with reference to the accompanying drawings.

A serial port communication isolation circuit, referring to FIG. 1, a second pin and a third pin of a digital isolator U6 are respectively connected with a receiving port and a sending port controlled by an external MCU, a sixth pin and a seventh pin are connected with a fourth pin and a third pin of a gating dial JP1, a first pin and a second pin of the gating dial JP1 are respectively connected with a twelfth pin and an eleventh pin of a serial port transceiver U5, and a fifth pin and a sixth pin are respectively connected with a first pin and a fourth pin of the serial port transceiver U8; a second pin, a sixth pin and a sixteenth pin of the serial port transceiver U5 are respectively connected with a capacitor C5, a capacitor C7 and a capacitor C8 in series and then grounded, and a thirteenth pin and a fourteenth pin are respectively connected with a second pin and a third pin of the data interface connector DB 9; an eighth pin of the serial port transceiver U8 is connected with the capacitor C11 in series and then grounded, and a sixth pin and a seventh pin are connected with the resistor R7 in parallel and then respectively connected with a seventh pin and an eighth pin of the data interface connector DB 9;

the digital isolators U6 and U9 of the utility model adopt ADUM1201 chips, the serial port transceiver U5 adopts MAX3232 chips, and the serial port transceiver U8 adopts MAX485 chips;

the working principle of the utility model is as follows:

the MCU is connected with the PC upper computer through a standard DB9, the interface is compatible with RS232 and RS485 simultaneously, serial port communication signals of the MCU are accessed through a second pin and a third pin of a digital isolator U6 and are subjected to level conversion and digital isolation through a digital isolator U6; selecting an RS232 or RS485 mode according to the decision of the gating dial JP1, and converting the mode to a standard DB9 pin standard definition connector through MAX3232 or MAX 485; the first pin, the third pin, the second pin and the fourth pin of the strobe dial JP1 are respectively short-circuited when RS232 mode communication is selected, and the fifth pin, the third pin, the sixth pin and the fourth pin of the strobe dial JP1 are respectively short-circuited when RS485 mode communication is selected; the RS232 main definition is a maintenance port and is used for functions such as online debugging, version upgrading and the like; the RS485 is mainly defined as a data interaction port, is a user application port and is used for the functions of parameter setting, control command issuing, data uploading and the like;

the circuit of the utility model solves the problems that one port is flexibly gated and compatible with two communication modes, the two communication modes are executed in different functions, the expandability is strong, the authority modes of maintenance personnel and users are distinguished, and major accidents caused by manual misoperation and wrong setting are avoided.

In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations can be made by the worker in the light of the above teachings without departing from the spirit of the utility model. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. A serial port communication isolation circuit is characterized in that: the device comprises a gating and dialing device, a first serial port transceiver, a second serial port transceiver and a data interface connector which are sequentially connected with a first digital isolator, an MCU serial port communication signal passes through the first digital isolator and then is connected with the gating and dialing device, and the gating and dialing device selects to transmit the MCU serial port communication signal to the first serial port transceiver or the second serial port transceiver and then is connected with an external upper computer through the data interface connector.

2. The serial port communication isolation circuit of claim 1, wherein: the second digital isolator is electrically connected with the second serial port transceiver.

3. The serial port communication isolation circuit of claim 1, wherein: the type of the first serial port transceiver is MAX3232, and the type of the second serial port transceiver is MAX 485.