阻塞模式主要用于无窗口、多线程处理中。启动服务之后应该启动一个线程来轮询DTU数据，收到数据后直接处理，或放数据缓存，再由其他线程来处理。-Blocking mode is mainly used for non-window, multi-threaded processing. After the start the service should start a thread to poll the DTU data, received data directly, or put the data cache, and then handled by another thread.