It is composed of master, relay unit and module unit.

控制系统由上位机、中继单元和模块单元构成。

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The function and principle of some intelligent units are introduced: status monitoring unit, operation unit, relay unit, measurement unit and record unit.

介绍了几种常见智能单元(状态监测单元、智能操作单元、继电保护单元、测量计量单元、设备记录单元)的功能和原理。

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The master communicates with the relay unit by serial communication interface and the relay unit communicates with module unit by wireless communication network.

上位机和中继单元之间采用串行口通信，中继单元和模块单元之间采用无线网路进行通信。

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On Day 44 of the trek, both a radar device meant to measure the ice thickness and a satellite communications unit to relay the data are still not working - despite being brought back to the UK for repairs and then delivered to the team last week.

BBC: Arctic team gives up on ice radar