I have a float OPCDA signal from PLC I want add payload to a posted MQTT topic Regards

[image] muharremsari: {"id":"Channel1.Device1.PMMTrkPyroStat1Temp","v":" Floating Value From OPCDA "} OK i am not sure if I understand correctly - but may be you meant this: [image] So use a change Node like this: [image] If you want that as JSON String put a JSON Node in as well: [im…

May be you should post an example. What is the payload which comes out of your mqtt node and what should be added?

Preformatted text [{"id":"b261f6b8f06331ab","type":"inject","z":"d2279fc8909d5ffb","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"Channel1.Device1.PMMTrkPyroStat1Temp","payload":"85","payloadType":"str","x":110,"y":60,"wir…

This is what you posted: [image] Is it correct that you got a string as output (or is it a number ? ) and what you want to add? A number, a string, an object???

I see value client machine. But i want get from opcclient like this address [{"id":"Channel1.Device1.PMMTrkPyroStat1Temp","v":"Floating Value From OPCDA"}] [image]

What is the difference - using a function node - instead of change node???? - More complex is always possible.

I am not very familiar with Jsonata so I naturally reach for a function node. There is no way I could convert the string to an object, convert the number to floating point and add it as a message property in Jsonata. I expect smarter people could, but if they did, how easy would the code be to und…

There are ways to convert in JSONATA, but that is not the topic. The payload is assigned without any modification to a property of an object. But even if you do not like to use JSONATA - it is still much easier to use a change node which does the same as your function node. Function nodes needs cod…

There are always lots of ways to solve any programming problem. I think your change mode version is better than mine. :grinning:

How to add payload to a posted MQTT topic?

General

jbudd 21 March 2022 13:20 5

I want add payload to a posted MQTT topic

This is your topic: "Channel1.Device1.PMMTrkPyroStat1Temp"
And this is your payload: "85"

If you add them together you get "Channel1.Device1.PMMTrkPyroStat1Temp85"

If the above is not what you are trying to achieve you will have to explain better.

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How to add payload to a posted MQTT topic?

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