Dear all, I'm using Node-RED version: v3.1.9 Node.js version: v20.12.2. I need to pass two variables (now i'm trying with just one, for the sake of simplicity) to a PLC and to do this I created a Modbus Server node like this: [image] Now I'm having two problems: The first one is, how can I se…

[image] Steve-Mcl: I'm certain non of that is news to you but, I've seen first hand (and in a thread recently) where inputting values into the server via it's input is a bit odd [image] Modbus Server not working General Steve's method works +1 Updated the Test Flow…

[image] Alphagamma: I need to pass two variables (now i'm trying with just one, for the sake of simplicity) to a PLC What is the make and model of the PLC. Why are you creating a server? Surely if the PLC supports Modbus it has a server that you simply connect to and set values using the rea…

Hi Steve, thanks for pointing me out the trick about the upscaling. Now, for the make and model, it's a BMS controller, in particular a Schneider Electric SmartX Controller AS-P. However, I wanted to create a Modbus TCP Server because i would like that the flow and the device where the flow is ru…

Dont try to populate values of the server via its input. Treat it like any other external modbus device & use the Modbus Read/Write/getter/setter nodes. As for formatting data, i recommend you spend some time getting to grips with data types and how they are represented within PLCs and their real …

[image] Steve-Mcl: Treat it like any other external modbus device & use the Modbus Read/Write/getter/setter nodes. So, are you saying that: i have to write the value coming from my procedures to the server (the same Node-RED), after that this value stored into the holding register can be read…

[image] Alphagamma: , are you saying that: i have to write the value coming from my procedures to the server (the same Node-RED), after that this value stored into the holding register can be read from the PLC. I have interpreted it right? Correct. [image] Alphagamma: but I'm very beginn…

[image] Steve-Mcl: [image] Alphagamma: , are you saying that: i have to write the value coming from my procedures to the server (the same Node-RED), after that this value stored into the holding register can be read from the PLC. I have interpreted it right? Correct. In that case I don…

I try to reply, just to to understand if my guessing is right: the same value written to a variable(s) will be available to the PLC by reading it indexed by its register created on the Modbus-Server node.

[image] Steve-Mcl: I recommend watching this playlist: Node-RED Essentials . The videos are done by the developers of node-red. They're nice & short and to the point. You will understand a whole lot more in about 1 hour. A small investment for a lot of gain. Thanks Steve, I had already seen th…

A modbus server typically has a memory bank/file where registers exist. A client connects and requests values. If the OP doesn't set values in the server they will be zero. Of course the client (in this case a PLC) can read and write values in a server, but that's not really useful by itself. Typi…

Thanks Steve, just found some minutes ago your reply in that thread.

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Convert a floating data variable to holding register on a Modbus Server (Slave) TCP

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Steve-Mcl 26 April 2024 19:56 11

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Convert a floating data variable to holding register on a Modbus Server (Slave) TCP

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