簡述：
用Node-RED 搭建一個(gè)MQTT網(wǎng)關(guān)，網(wǎng)關(guān)通過Modbus總線連接一個(gè)水位傳感器和一個(gè)溫度傳感器，采集水位和溫度數(shù)據(jù)，再通過MQTT客戶端把水位和溫度信息發(fā)布到MQTT代理。
網(wǎng)關(guān)：
協(xié)議轉(zhuǎn)化：網(wǎng)關(guān)可以通過Modbus總線把多個(gè)485串口的傳感器，以輪詢的方式采集，通過MQTT協(xié)議發(fā)布給信息平臺(tái)。
信息匯聚：網(wǎng)關(guān)可以把多個(gè)傳感器數(shù)據(jù)，聚合為一個(gè)對(duì)象，為數(shù)據(jù)附加語義描述，使信息具有結(jié)構(gòu)化，易可識(shí)別。
虛擬串口軟件VSPD配置兩對(duì)虛擬串口：
Modbus Slave模擬兩個(gè)傳感器：
配置MQTT代理：
通過Modbus分別采集水箱的水位和溫度，合并為水箱參數(shù)，由MQTT客戶端發(fā)布：
添加注入(inject)節(jié)點(diǎn)和延遲(delay)節(jié)點(diǎn)配置輪詢：
文章來源：http://www.zghlxwxcb.cn/news/detail-700909.html
添加函數(shù)節(jié)點(diǎn)，為消息添加主題：
文章來源地址http://www.zghlxwxcb.cn/news/detail-700909.html
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