Transfer a change from one node to all the same nodes

[volker1078]

I wanted to ask if it is possible to change several nodes at the same time. As an example, I have several switch or range nodes in my flow for which I would like to change the entered values. I change the value of one node and this value is transferred to all other nodes in the flow. Something like a global variable, is there something in Node-Red?

Greetings Volker

[Steve-Mcl]

@volker1078

Something like a global variable

like this?

[volker1078]

i don't understand it yet. can you give me more information?

[Steve-Mcl]

Sure.

You can store a value in a global variable (called context) and re-use it as many times as you like - just like you asked.

Here is even more info

[volker1078]

Hello,

Thank you for your answer. I finally found time to test this time and managed to do it with the change and function Node. Now I wanted to ask whether it is possible to define the range node as a global variable. In my flow, the message payload runs repeatedly through an A / D converter node and then through the change node. There are a total of 16 change nodes in the flow and it is tedious to change the values ​​for all of them one after the other.

So my question again is it possible to change the values ​​of a change node and these are transferred to all others?

Here is a screenshot of my change node

Thank you for your efforts

Greetings Volker

[Colin]

It is trivial to implement a Range node using a function node, in the function you could send it a message to change the range, or use flow/global context to define the range.

[Steve-Mcl]

you cant use flow or global variables for these but you can use environment variables

[Colin]

So we understand better, why do you have to change the ranges routinely.

[volker1078]

do you have an example for this which explains exactly how it works? do you need an inject node for this?

[Steve-Mcl]

I don't understand.

Only you know how you want to use the scale node.

Your picture where you drew red circles around the boxes - I demonstrated that while you cannot use global variables, you can use environment variables.

Do you know what environment variables are and how to use them?

[volker1078]

no, unfortunately I don't know.

even from the node-red documentation, I do not judge really smart ...

https://nodered.org/docs/user-guide/environment-variables

how can I define the environment variables and retrieve them again?

[Steve-Mcl]

So environment variables are set in your operating system before you launch node red.

For example, on Windows you might have a batch file that launches node-red. You can set up some variables before you launch node-red (like constants) that you can pick up in node-red

E.g., your batch file might be something like...

set f1=0
set t1=4095
set f2=1
set t2=100
node-red

Then when node-red is running, you can pick up the value of these & use them in the range node (and other nodes)

If you use Linux, then it would be export f1=0 etc.

[volker1078]

I got it done.
with your advice and this page it worked.
https://flows.nodered.org/flow/8a13d11dfe80e279df83341e3e17bcc1