485 bus system and method for transmitting data

Abstract

The invention is designed for use in overcoming the disadvantage existed in currently-used technology, which is the communication in point-to-multipoint is only capable of using half-duplex communication mode. The invention provides a 485 bus system, which comprises a master device and multi slave devices; the connection between the master device and the multi slave devices is based on two buses independently each other. The method thereof comprises: the slave devices send uplink data to master device through one bus, and the master device sends downlink data to the slave devices through downlink another bus.

Description

technical field [0001] The invention relates to the communication field, in particular to a 485 bus system and a method for transmitting data by using the 485 bus system. Background technique [0002] The RS485 communication standard is an electrical characteristic standard of a digital multipoint system using differential balanced transmission, which can support driving 32 loads at the same time, and has the advantages of strong anti-common-mode interference ability. When the transmission distance of RS485 does not exceed 50Ft, the maximum rate can reach 10Mbps; when the transmission rate is 100Kbps, the maximum transmission distance can reach 4000Ft. 485 communication technology is mainly used in the application fields of point-to-point, multi-point and point-to-multipoint intercommunication. [0003] In the application environment of point-to-multipoint intercommunication, generally a master device will communicate with multiple slave devices, and each slave device does ...

AI Technical Summary

Problems solved by technology

[0005] 1. Since the receiving and sending of the master device and each slave device are connected together and share the same bus, only half-duplex communication can be used, and the receiving and sending cannot be performed at the same time, and the communication bandwidth will be reduced by half

[0006] 2. There is bus contention between multiple slave devices when the slave device is sending, and conflict detection needs to be performed through the conflict detection signal port. It is difficult to make the communication rate too high. Currently, it can only work below 4Mbps.

[0007] 3. Since multiple slave devices need to perform conflict detection, the clocks of all slave devices must be the same. In the prior art, the sending clock terminals and receiving clock terminals of the master device and the slave device are connected to the same clock, so The receiving rate and sending rate of each device are the same. For the application scenario where the amount of downlink data sent from the master device to the slave device is larger than the amount of uplink data sent from the slave device to the master device, due to the limitation of the uplink rate, the downlink rate cannot exceed 4Mbps

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