Full-duplex rs485 bus communication method based on non-conflict protocol

Abstract

The invention discloses a device and a method for full duplex RS485 bus communication based on collision-free protocol and belongs to the technical field of RS bus communication. The device and the method mainly solve the problem that existing RS485 buses cannot meet real-time system monitoring requirements of many monitoring nodes and huge data volume of single node uploading and are mainly characterized in that a bus data interception circuit feeds data on a sending bus back to a PLD (programmable logic device) chip, a PLD chip circuit judges occupied state of a bus and calculates data sending delay time factor through sending of bus exploring frames, if the time factor is zero, the RS485 data sending bus is grabbed to be sent, and if not, a certain time is delayed until the sending is finished. The device and the method for full duplex RS485 bus communication based on bus collision-free protocol have the advantages of realization of collision-free sending of effective data frames on the RS485 data sending bus, elimination of bus spare time on the data sending bus, effective reduction of bus collision probability of sending of the exploring frames and great improvement of utilization efficiency of the data sending bus.

Description

technical field [0001] The invention belongs to the technical field of RS485 bus communication. Specifically, it relates to a full-duplex RS485 bus communication method based on a bus conflict-free protocol. Background technique [0002] The RS485 bus has the characteristics of strong anti-interference ability, long transmission distance, flexible networking, and high cost performance. It is widely used in industrial control automation, traffic control automation and other systems. However, in some industrial monitoring systems, due to the large number of monitoring nodes, the amount of data uploaded by a single node is huge, and the system has strong requirements for real-time data, so the RS485 bus using traditional single-duplex communication cannot meet the system monitoring requirements. [0003] At present, in the RS485 bus system that adopts full-duplex communication mode in China, the conflict retransmission mechanism is mostly used to solve the bus conflict, whethe...

AI Technical Summary

Problems solved by technology

However, in some industrial monitoring systems, due to the large number of monitoring nodes, the amount of data uploaded by a single node is huge, and the system has strong requirements for real-time data, so the RS485 bus using traditional single-duplex communication cannot meet the system monitoring requirements.

[0003] At present, in the RS485 bus system that adopts full-duplex communication mode in China, the conflict retransmission mechanism is mostly used to solve the bus conflict, whether it is using a timer for conflict detection, bus idle monitoring, or using a virtual full-duplex with a data buffer. There are bus data conflicts in the work mode, or the conflict resolution of sending and receiving by using the CSMA / CD protocol or the table look-up method

However, the method of using the bus node grouping method to deal with the conflict waiting time, although the bus conflict can be reduced to 0 through a large number of groups, but this brings the problem that the bus device address is greatly restricted, and it is subject to greater restrictions and limitations in practical applications. influences

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