Semi-competitive rs-485 bus multi-master communication system and its working method

Abstract

A half-competition model RS-485 bus multimaster communication system relates to a communication system. According to an RS-485 bus scheme at present, once a conflict occurs, competition needs to be carried out again. The half-competition mode RS-485 bus multimaster communication system of the present invention is characterized in that a master node is connected with a bus via a first interface chip, and each slave node is connected with the bus via a second interface chip and is equipped with an XNOR gate circuit, a double-path D-type rising edge trigger and an XOR gate circuit; the output end of the XOR gate circuit and a slave node receiving signal end are connected with the second interface chip, a first resistor is arranged between the second interface chip and the anode of a power supply, and a second resistor is arranged between the second interface chip and a grounding end; a sending signal end and a receiving signal end of the master node are connected with the first interface chip directly, and the first interface chip is connected with the power supply via a pull-up resistor and is grounded via a pull-down resistor. The half-competition mode RS-485 bus multimaster communication system and the working method thereof of the present invention are based on the hardware, monitor and receive the sent data, and are stable in work, high in reliability and faster in speed.

Description

technical field [0001] The present invention relates to a communication system. Background technique [0002] In the traditional RS-485 bus, there is one master node and multiple slave nodes. Its working process is as figure 1 As shown, the communication is always initiated by the master node. After receiving the command, the slave node obtains the control right of the bus, and then sends information to the bus. After sending, the bus control is returned to the master node. Slave nodes can only send data when inquired by the master node, so emergency data such as alarms cannot be transmitted; slave nodes cannot communicate with each other, and can only be transferred through the master node, which affects the speed; in order to improve the speed of slave nodes and improve the real-time performance of the system , the School of Automation Science and Engineering of South China University of Technology in Guangzhou proposed a multi-master RS-485 bus solution to realize carr...

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Problems solved by technology

Slave nodes can only send data when inquired by the master node, so emergency data such as alarms cannot be transmitted; slave nodes cannot communicate with each other, and can only be transferred through the master node, which affects the speed; in order to improve the speed of slave nodes and improve the real-time performance of the system , the School of Automation Science and Engineering of South China University of Technology in Guangzhou proposed a multi-master RS-485 bus solution to realize carrier sense multi-point access / collision detection. Through software, its workflow is as follows figure 2 As shown, the data transmission speed is correspondingly improved, but it can only detect bus conflicts, and cannot actively avoid them. Once a conflict occurs, communication fails and requires re-competition

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