Controller local net bus physical relay

Abstract

This invention discloses a physical relay of a controller area network (CAN) bus including a CAN transceiver and a logic control circuit, among which, the CAN transceiver is used in converting circuit signals to logic level, the logic circuit controls the transmission directions and switches dead band time. The invented relay is suitable for various rates of communications having the advantages of keeping data transparent transmission, increasing transmission distance and node numbers and separating short circuit faults.

Description

technical field [0001] The invention relates to a controller local area network bus physical repeater, which belongs to the field bus transmission field. Background technique [0002] Fieldbus technology is applied in fields such as industrial control, intelligent building characters, and equipment monitoring. Controller Area Network (hereinafter referred to as CAN) bus is a cheap field bus, widely used in many occasions. Its biggest feature is the use of non-destructive arbitration technology, which can ensure that the network maintains the maximum throughput even under heavy load conditions. [0003] The CAN bus usually uses twisted-pair wires for transmission. At present, the CAN node communication is generally transmitted directly through the CAN transceiver connected to the bus segment. There are still the following disadvantages: the electrical characteristics of the transceiver limit the number of nodes in a CAN network segment to no more than 110; The characteristi...

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Problems solved by technology

[0003] The CAN bus usually uses twisted-pair wires for transmission. At present, the CAN node communication is generally transmitted directly through the CAN transceiver connected to the bus segment. There are still the following disadvantages: the electrical characteristics of the transceiver limit the number of nodes in a CAN network segment to no more than 110; The characteristics of the transmission line limit the actual transmission distance to the theoretical limit; a fault on the bus will affect the communication between all nodes

However, the method of extending the CAN bus by relaying at the data link layer needs to be controlled by the MCU, and there must be a CAN controller and a data buffer. The circuit is complex and can only be targeted at a certain frequency.

There is also a major defect, that is, the bit response mechanism between the sending node and the final receiving node of the CAN bus is destroyed, so that the sender cannot judge whether the final receiving node has received data through the response bit

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