Method for improving RS485 communication reliability

Abstract

The invention discloses a method for improving RS485 communication reliability. The method comprises a microcontroller MCU. The microcontroller MCU is connected with a first RS485 interface chip and asecond RS485 interface chip through a UART interface, wherein an RXD end of the UART interface of the MCU is connected with an RO end of the first RS485 interface chip; a TXD end of the UART interface of the MCU is connected with a DI end of the second RS485 interface chip; and bus interface pins A and B of the first and second RS485 interface chips are connected in parallel to a 485 communication bus. The method finishes data sending and receiving through two RS485 interface chips, and can completely eliminate reception dead zones during sending and receiving enable switching when the RS485receive, thereby improving RS485 communication reliability.

Description

technical field [0001] The invention discloses a method for improving the reliability of RS485 communication, which relates to the technical field of electronic communication. Background technique [0002] RS485 communication is a widely used data communication method, often used between centralized control units and decentralized control units. RS485 communication port adopts differential signal negative logic, +2V ~ +6V means "0", -6V ~ -2V means "1". RS485 has two types of wiring, two-wire system and four-wire system. The four-wire system is a full-duplex communication mode, and the two-wire system is a half-duplex communication mode. In the RS485 communication network, due to the convenience of wiring, the half-duplex master-slave communication method is generally adopted, that is, one master has multiple slaves, and the two communication lines of the master and slaves are connected in parallel. [0003] When half-duplex RS485 communication is used, the typical design ...

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Problems solved by technology

[0003] When half-duplex RS485 communication is used, the typical design method is to use the UART interface of the microcontroller MCU to the RS485 communication chip through the photoelectric isolation interface to realize RS485 communication, and the sending pin TXD of the microcontroller MCU is connected to the RS485 communication through photoelectric isolation. The DI of the interface chip, the receiving pin RXD of the microcontroller MCU are optically isolated to the RO of the RS485 communication interface chip, and the sending enable pin TXEN of the microcontroller MCU is optically isolated to the sending and receiving enable of the RS485 communication interface chip pin to realize the RS485 communication interface; in the above design, when the microcontroller MCU needs to send data, first set TXEN to send the enable, and then send the data. The RS485 bus responds to the data. Waiting for the data transmission to be completed, there is a receiving dead zone for a period of time when the receiving enable is set. During this period of time, the RS485 interface chip cannot receive the received data because the RS485 interface chip is set to transmit. The response message responds to the data within the receiving dead zone, and the microcontroller MCU cannot receive the correct response data

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