Repeated interrupt mode 485 direction control method

Abstract

The invention relates to a repeated interrupt mode RTS / 485 direction control method. A 16550 UART (universal asynchronous receiver / transmitter) compatible control chip is a standard serial port controller of a PC (personal computer) and widely used in an embedded system, and RTS signals of the control chip can be used for 485 bus transceiving direction control, RTS pin signals are controlled by the interrupt generation mode, enabling signals transmitted by the 485 bus can be recovered in time, the purpose of accurate control of the 485 bus direction can be achieved without modifying hardware design, and the repeated interrupt mode 485 bus direction control method is applicable to communication of medium and high speed 485 buses. Besides, for low-speed 485 communication, time delay control mode can still be adopted.

Description

technical field [0001] The invention belongs to the technical field of industrial control and electric power system automation, and relates to a method for controlling the direction of a repetitive interrupt mode RTS / 485. Background technique [0002] With the continuous development of power system automation technology and the extensive use of smart devices in substations and distribution stations, data exchange between smart devices and systems is becoming more and more important. Therefore, connecting and managing data communication interfaces between devices and systems has become a power Indispensable and important equipment for the system automation system. [0003] The RS-485 serial interface is a low-speed long-distance communication interface commonly used in the field of industrial control and power system automation. [0004] RS-485 is developed on the basis of RS-232 and RS-422. RS485 adopts differential signal negative logic, +2V~+6V means "0", -6V~-2V means "...

AI Technical Summary

Problems solved by technology

However, for non-real-time operating systems like Windows, the highest resolution of the kernel clock is 1ms, and the accuracy of the timer is between 1-2ms. At 9600 baud rate, the time of 1 byte is about 1ms. The measured timer It will cause the sending driver of MAX485 to open more than 1 byte, which will cause problems when communicating between high-speed 485 terminals

Due to the limitation of the clock resolution of the operating system, the precision of the delay control is low, which cannot meet the requirements in medium and high speed 485 communication

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