Connect to an MQTT Broker
Problem
You want to connect to an MQTT broker running locally.
Solution
Use the MQTT Input input or MQTT Output node
and an associated MQTT Config node to connect to an MQTT broker.
Example
[{"id":"2c6873d2.992abc","type":"mqtt out","z":"eda2a949.74ea98","name":"","topic":"sensors/livingroom/temp","qos":"","retain":"","broker":"407a01e4.6b637","x":330,"y":80,"wires":[]},{"id":"d9beed59.94155","type":"inject","z":"eda2a949.74ea98","name":"","topic":"","payload":"22","payloadType":"num","repeat":"","crontab":"","once":false,"x":150,"y":80,"wires":[["2c6873d2.992abc"]]},{"id":"be80048.8f232f8","type":"mqtt in","z":"eda2a949.74ea98","name":"","topic":"sensors/livingroom/temp","qos":"2","broker":"407a01e4.6b637","x":170,"y":160,"wires":[["8640b8ff.f82ff8"]]},{"id":"8640b8ff.f82ff8","type":"debug","z":"eda2a949.74ea98","name":"","active":true,"console":"false","complete":"false","x":370,"y":160,"wires":[]},{"id":"407a01e4.6b637","type":"mqtt-broker","z":"","broker":"localhost","port":"1883","clientid":"","usetls":false,"compatmode":true,"keepalive":"60","cleansession":true,"willTopic":"","willQos":"0","willPayload":"","birthTopic":"","birthQos":"0","birthPayload":""}]
Discussion
Many users will run an MQTT broker such as mosquitto on
the same Raspberry Pi or PC that Node-RED is running on. Once you have an
MQTT input or output node in your flow, you create an
MQTT Config node by clicking on the Server configuration
pop-up and selecting Add an MQTT broker.... Assuming your broker is open,
set the server host to localhost and leave the port set to 1883.
To connect to non-local, secured brokers, other MQTT Config
node options will need to be set according to your broker’s connectivity requirements.