Hi all I am very new to node-red and have a simple question(to some). I have two Raspberry pi's that I want to monitor from my windows laptop, I have set up a flow but I cant seem to use the two different pi IP addresses. the all change to the same IP when I enter them flows (1).json (22.2 KB) …

I can't look at your flow, as I am on my phone. Are you running one MQTT broker or two? For future reference you should paste flows inline see this post for more details - How to share code or flow json

You should have one mqtt broker and it will have an IP address. This broker could be installed on eithor Pi or a seperate Pi (I have mine installed on a Pi Zero W). The IP address of the machine that has the broker is the one you will enter when configuring the mqtt nodes on both pi's. There is a g…

I think your understanding of MQTT maybe incorrect. As the name suggests, a broker sits in the middle of all parties. You really only need one broker and you point every device at the one single broker. The way to differentiate messages is through using different topics. This diagram may help... […

I think that diagram might be slightly out-of-date as the current (best practice) way of setting a 'topic' doesn't start with a forward slash (as it adds a extra level of hierachy that isn't needed). [mqtt_topic_slash]

Good point and absolutely correct - well spotted Dave.

Ok so there is no other way to do it but to use something like test.mosquitto.org . that poses another problem in that if one pi goes down test.mosquitto.org does not show that the one is down. Or is there another way I can perhaps achieve my goal. As I said I am very new to node-red

Just looked at your flow. All I can see are MQTT-In nodes (subscribe nodes). There are no MQTT-Out nodes (publish nodes). [just_in_nodes] I suggest you try creating a very simple flow to check if Mosquitto is working... like this... [test_A] [test_B]

That is ok, there is no problem with having a broker on each pi, that is what I usually do. When you configure the brokers in the mqtt nodes you have to use Add new server to add the second one, so you have two in the drop-down list. One for each pi.

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How to use different IPs with mqtt

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shaunfish 30 October 2022 08:32 7

I have two, each on its own pi

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How to use different IPs with mqtt

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