The hardware of the system is built on the layout network of the doorphone system, and CAN BUS is used as the trunk line of communication to improve the real time performance and reliability.

系统硬件利用楼宇访客系统的布线网络，通信干线采用CAN总线，以提高通信的实时性和可靠性。

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As there is something wrong with the trunk line of the network, the transmission of data is blocked. The technical staff is urgently repairing it.

由于网络的中继线出了问题，造成数据通信不畅，技术人员正在抢修。

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Then divides the highway network into four levels: main trunk line, sub-trunk, feeder and connecting line, and also positions functions of the four levels.

进而按照通达程度将公路网划分为四个等级：主干线、次主干线、支线和连接线，并分别对四个层级进行了功能定位；

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