Method for controlling multi-node RS485 bus data transmission right

A technology of RS485 and control method, which is applied in the direction of bus network, data exchange through path configuration, etc.

Active Publication Date: 2012-09-12
ANHUI KELI INFORMATION IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, there has not been any node taking a certain time period as a cycle to obtain the sending right of the bus equally and in turn.

Method used

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  • Method for controlling multi-node RS485 bus data transmission right
  • Method for controlling multi-node RS485 bus data transmission right
  • Method for controlling multi-node RS485 bus data transmission right

Examples

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Embodiment Construction

[0017] A method for controlling the data transmission right of a multi-node RS485 bus, the method includes the following sequential steps: (1) Select the time period T of time-division multiplexing as the maximum allowable time for system data delay; (2) According to the system internal RS485 The number of nodes on the bus, divide the time period T into N time periods, and then determine each time period t according to the amount of data sent by each node n The value of ; (3) In a time period T, each time period t n Correspondingly select a node to obtain the RS485 bus transmission right, and other nodes are in the receiving state; (4) Repeat step (3). Such as figure 1 shown.

[0018] Such as figure 2 As shown, different systems have different requirements for communication data delay, and an appropriate time period T is selected as the time-division multiplexing cycle period, and this time period T is the maximum allowable time for system data delay. Then, according to t...

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Abstract

The invention relates to a method for controlling multi-node RS485 bus data transmission right. The method includes following sequential steps: selecting time-sharing multiplexing time cycle T as maximum allowable time of system data delay; dividing the time cycle T into N time slots according to node number of the RS485 bus in the system, and determining value of each time slot tn according to amount of data transmission of each node; each time slot tn selecting a node to obtain the transmission right correspondingly in the time cycle T and the other nodes are in a state of receiving; repeating the previous step. By the method, fewer hardware resources are used, the RS485 is used to communicate with two signal lines, function of time-sharing and multiplexing of the RS485 data bus is realized with fewer bus control commands is realized, and each node of the bus can transmit data equally.

Description

technical field [0001] The invention relates to the field of multi-node RS485 communication control, in particular to a control method for multi-node RS485 bus data transmission right. [0002] Background technique [0003] RS485 is a level protocol of the USART serial port. It usually only uses two signal lines to work, that is, the voltage difference between the two lines is used to represent data information. It can carry out multi-node communication, but it is a half-duplex communication, and there can only be one data transmitter at the same time point, and other nodes can only be used as receivers. Multiple driver boards on the RS485 bus must be able to synchronize and coordinate to realize the control of the entire intersection signal lights, so its time synchronization and orderly communication are crucial. In software design, it is necessary to ensure that the time synchronization of signal light state switching is not disordered, and the sending and receiving of c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L12/40
Inventor 朱有祥陈鹤梁子君宋志洪宣林川
Owner ANHUI KELI INFORMATION IND
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