Hi, Is there a way to modify the topic of mqtt input nodes from one script ? and then do a full deployment . I did one script to modify topics in the flow file (from command line), but it’s necessary to stop node-red and then restart it for getting it working. (too long process). I am wondering i…

Hi, I tried the two ideas : from dceejay about using the environment variables. We can do use env_var into the nodes with the limitation that the content of variables will be the one at the node-red start time. If we modify the environment variables (using the same console where we started the …

You cannot change the topic of MQTT input nodes apart from editing them. Just use multiple nodes if possible. Show us what you are trying to do, there may be another way.

I have several identical controllers. All of them reporting to the same broker. The topics are the same for every device, the only difference is the name of the topic first level path which is equal to the device serialNumber, so the topic for variable1 in the device 1 will be serialNumber1/variable…

Use the MQTT wildcard + in the first level?

As per my understanding using wild card subscribe you to all topics under the wild card and I only want to be subscribed to the topics of one device. I have al least 50 devices.

The existing MQTT nodes do not provide a way to dynamically change their subscriptions. This has recently been discussed here: Trigger a mqtt subscription

I meant instead of serialNumber2/variable1 use +/variable1. The whole topic will still get passed into the flow.

thank you Nick for your comment. I already tested the node-red-contrib-mqtt-dynamictopic but as per my tests, it does not unsubscribe the previous topic before subscribe the new one ( and I did not find a way to do it) so, after some topics changes I keep subscribed to a lot of topics creating an u…

I understand that if I do +/variable1 I will received the variable1 of the 50 devices, creating an unnecessary traffic in my lan. I only need the variable1 of one device. am i wrong ? thx

If it’s based off the serial number then maybe use the $(env_var) syntax instead for the topic. And set the appropriate environment variable outside of Node-RED.

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Change mqtt-input node topic name

General

ghayne 27 July 2018 19:50 10

That's true, but surely not a problem for the network. How often do you need to change the device?

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Change mqtt-input node topic name

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