EG边缘计算网关连接华为云物联网平台（MQTT协议）

需求概述

实现一个流程：EG8200mini采集Modbus RTU数据，通过MQTT协议连接华为云物联网平台

Modbus RTU采集此处不做过多赘述，可参考其他案例（串口读取Modbus传感器数据）介绍。下文默认已经采集到Modbus RTU数据。

要采集的Modbus点位表：

地址(Doc)	数据类型	属性	名称
00001	Boolean	读写	MotorControl1
00002	Uint16	读写	MotorControl2
40001	Uint16	读写	Requency1
40002	Uint16	读写	Requency2

MQTT通信相关参数及JSON数据格式要求，参考华为云设备属性上报_设备接入 IoTDA：

发布主题（Topic）：$oc/devices/{device_id}/sys/properties/report
数据格式样例：   
{"services": [{"service_id": "Temperature",	//服务ID"properties": {"value": 57,	//属性名称"value2": 60	//属性名称}}]
}

需求分析

网关配置：

第一步：采集Modbus RTU数据

第二步：拼接Json

第三步：MQTT上报

平台配置：

第一步：添加产品

第二步：添加物模型

第三步：添加设备

第四步：数据展示

需求实现

网关配置

第一步：采集Modbus从机的数据

此处为采集Modbus RTU数据，不在过多赘述，可参考其他案例。采集到Modbus RTU的流程如下：

此处为语雀内容卡片，点击链接查看：Modbus RTU 读数据 · IOTRouter

源码：

[{"id":"d968892da4e40a46","type":"inject","z":"b7c6f1e56286d94a","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"5","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":480,"y":1780,"wires":[["9b935c0dd6a63827","3bc2eb81af744a6d"]]},{"id":"9b935c0dd6a63827","type":"modbusRead","z":"b7c6f1e56286d94a","name":"读线圈","uid":"1","dataType":"1","len":"120","modbus":"f4b98c3be57ddcad","columns":[{"Key":"MotorControl1","Address":"0","Type":"23","Tdata":""},{"Key":"MotorControl2","Address":"1","Type":"23","Tdata":""}],"x":670,"y":1780,"wires":[["de1ce0dfa2e082f8"]]},{"id":"30fa1cad395c11c4","type":"modbusRead","z":"b7c6f1e56286d94a","name":"读频率","uid":"1","dataType":"3","len":"120","modbus":"f4b98c3be57ddcad","columns":[{"Key":"Requency1","Address":"0","Type":"1","Tdata":""},{"Key":"Requency2","Address":"1","Type":"1","Tdata":""}],"x":670,"y":1860,"wires":[["de1ce0dfa2e082f8"]]},{"id":"de1ce0dfa2e082f8","type":"join","z":"b7c6f1e56286d94a","name":"","mode":"custom","build":"merged","property":"payload","propertyType":"msg","key":"topic","joiner":"\\n","joinerType":"str","accumulate":false,"timeout":"0.5","count":"","reduceRight":false,"reduceExp":"","reduceInit":"","reduceInitType":"","reduceFixup":"","x":870,"y":1820,"wires":[["b53287da47908499"]]},{"id":"3bc2eb81af744a6d","type":"delay","z":"b7c6f1e56286d94a","name":"","pauseType":"delay","timeout":"200","timeoutUnits":"milliseconds","rate":"1","nbRateUnits":"1","rateUnits":"second","randomFirst":"1","randomLast":"5","randomUnits":"seconds","drop":false,"allowrate":false,"outputs":1,"x":470,"y":1860,"wires":[["30fa1cad395c11c4"]]},{"id":"b53287da47908499","type":"debug","z":"b7c6f1e56286d94a","name":"调试 254","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":1040,"y":1820,"wires":[]},{"id":"f4b98c3be57ddcad","type":"modbus config","name":"","model":"2","host":"127.0.0.1","port":"502","serialport":"/dev/ttyAS3","baudrate":"115200","databits":"8","stopbits":"1","parity":"none","timeout":"50","reqtimeout":"1000"}]

第二步：拼接Json

参考需求概述的MQTT数据格式以及平台配置第二步的物模型设置。将网关配置第一步采集的数据JSON格式化：

源码：

var data = msg.payload
msg.payload = JSON.stringify({"services": [{"service_id": "serverId","properties": {"temMotorControl1p": data.MotorControl1,"MotorControl2": data.MotorControl2,"Requency1": data.Requency1,"Requency2": data.Requency2},}]
})
return msg