DAU (Distributed Access Unit) is the distributed access unit of the CFDA system, which can respond to all the commands of the Micro Cell Access Center (CAC) of the CFDA system to complete the establishment of the micro cell network, network maintenance, data collection, etc. In the non-networking state, DAU can actively initiate a network access application, join the network to which it belongs, and provide a reliable network foundation for the application of wireless ad hoc networks. DAU equipment is generally installed on the user's data acquisition equipment (such as a digital energy meter), communicates with the data acquisition equipment downwards to complete data acquisition, and communicates with CAC upwards to complete data reporting.