Hello everyone, i’m trying to log some values from modbus devices to the mySQL node. the flow is not very clear to me as functionality and setup, so i’m posting here what i’m trying to do and asking how is possible to achieve something like this. I’m familiar with the modbus read and buffer parser…

Use the Flex Getter node, so that you manually trigger the reads, and read them in series not in parallel. So read from the first device, feed it through the parser, and save the results in, for example, msg.device1, then use that message to trigger the second getter node, feed the results through t…

Thanks for your comment. what is the input of the modbus flex getter ? i assume is the modbus parameters needed. can this be done with template ? i’m not familiar with javascript.

[image] BambosD: what is the input of the modbus flex getter The node-red-contrib-modbus module has built in help for each of its nodes (see the RH sidebar) and lots of built in example flows that you can access via CTRL-I -> examples -> node-red-contrib-modbus

Hello Mr Steve, i used a template node with output parsed json and feed the flex getter. this point it works ! Then i use a buffer parser to process the modbus registers as usual and get key/values json object to add variable names and then set output property on msg.device1 for identification. W…

[image] BambosD: it seems that flex getter node not passing the previous messages, not allowing for aggregation. Check the flex getter edit dialog - IIRC it has an option to "keep existing msg props" (I forget the name)

[image] BambosD: i used a template node with output parsed json and feed the flex getter Usually you would use a Change node for this. Why do you need to use a template?

thank you very much, this was the issue. now i have all devices. [image] what would be the recommended to merge those ?? change node ?

is just for easier reading and typing. with template i have it like this: { "fc":3, "unitid":100, "address":51003, "quantity":2 } with a change node everything is populated in a single text box like below: [image]

Yes, or a function node. What I dont understand is why do you always access the same modbus server and same address for these values? If all values are from the same modbus server/unit ID, then you could do this all in one request and one buffer parser.

yes, is proof of concept now using only the first device. in reality is 4 different devices as the prototype here, and unfortunately with different encoding methods. (the usual modbus headache). How it sounds to you to merge all the devices json objects with a change node and JSONata expression ?

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Modbus to mySQL flow suggestions

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Steve-Mcl 6 August 2025 14:47 9

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Modbus to mySQL flow suggestions

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