Its first function is to provide a route to earth for the heater relay.
第一个功能是提供一个接地路线给加热器继电器。
2
A set of relay protocols are designed to make the system have relayfunction, which spread the work range of concentrator and reduce the costs of installation and maintenance.
同时设计了一套中继通讯协议，使终端具有中继功能，扩充了集中器的管理能力，降低了安装和维护费用。
3
A set of relay protocol is designed for relayfunction.