A multi-master rs485 bus arbitration method and system
A RS485 and bus arbitration technology, applied in the field of bus arbitration, can solve the problems that the device cannot be increased or decreased at will, and the real-time performance of key information cannot be guaranteed.
Active Publication Date: 2019-01-04
浙江众合科技股份有限公司 +1
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However, this method is only suitable for periodic data transmission, not event-based data transmission, and cannot guarantee the real-time requirements of key information, and this method cannot realize the random increase or decrease of all devices on the bus
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[0027] In order to better illustrate the present invention, the present invention will be described in detail with a preferred embodiment and with accompanying drawings, specifically as follows:
[0028] The multi-master RS485 bus arbitration method provided by this embodiment is mainly applied in a three-wire RS485 bus system, the three-wire RS485 bus system includes two signal transmission lines and is provided with an arbitration signal line COD, and the multi-master RS485 bus includes multiple A main node, these nodes transmit data through the bus. Such as figure 1 As shown, the form of the arbitration signal line COD involved in this method is shown in the figure, which is set to include a collision detection line 1 (Collision Detectline, COD for short) and a bus arbitration circuit 2, and the collision detection line 1 and the two signal The transmission lines 3 and 4 are arranged in parallel, and the two signal transmission lines 3 and 4 are connected to the microcontr...
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The invention provides a multi-master RS485 bus arbitration method and system. The multi-master RS485 bus arbitration method is applied to a three-wire system RS485 bus, and the three-wire system RS485 bus comprises two signal transmission lines and is provided with an arbitration signal line COD. The multi-master RS485 bus arbitration method comprises steps of 1) setting a bus occupation detection mechanism; and 2) controlling a node needing to send data to preempt the bus according to the bus occupation detection mechanism. The bus occupation detection mechanism comprises that the node needing to send data firstly monitors whether the bus is busy; if the bus is not busy, the node occupies the bus to send data, and the arbitration signal line COD is set to be an occupancy state, after the node sends the data, the arbitration signal line COD is released, and the occupancy state is changed into an idle state; if the bus is busy, whether the bus is busy is monitored after a preset time period. The multi-master RS485 bus arbitration method and system are suitable for event data sending occasions, and key information needing to be sent can be transmitted timely.
Description
technical field [0001] The invention relates to the technical field of bus arbitration, in particular to a multi-master RS485 bus arbitration method and system. Background technique [0002] In a multi-master RS485 communication system, when only one master node sends data at the same time, other nodes can receive it correctly; when more than one node wants to send data on the bus at the same time, multiple RS485 devices may apply to use the bus at the same time. In order to avoid bus usage conflicts, a bus arbitration mechanism is generally used to manage devices that may occupy the bus in the system, so as to control the timing of each device accessing the bus when multiple devices apply for the bus at the same time. [0003] The traditional multi-master RS485 bus arbitration mechanism mainly ensures that only one node on the bus is sending data at a time by adopting time-division multiplexing and assigning the sending rights of nodes on the bus. However, this method is o...
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IPC IPC(8): G06F13/40G06F13/42
CPCG06F13/4031G06F13/4204
Inventor 姜雪明赵鸿鸣陈志华
Owner 浙江众合科技股份有限公司