Best way to send a message only when Node-RED has started and running

General
1

What is the best way to detect Node-RED starting, running so I can start a connection to OPC-UA I/O?

Thanks,

2

You can use an inject node with the once option, which will send a single message after 0.1s (configurable).

3

Sure, Is it that simple?

I guess what I was asking is this the means for a "First Scan" ? Maybe this is it.

I got looking at "Function" and the On Start script. Not sure the purpose of this. The context isn't clear.

Thanks.

4

You can also use the "On Start" part in which you add this to send a message at startup:

node.send({ payload: "Started" });

No inject node needed for this option.

5

As far as I know (and would ask to be corrected in case I'm wrong), there is a risk that the sender node sends the on-start message to a node which has not been initialized yet and cannot receive the message.
Since the node initialization sequence goes tab by tab, left to right, I would suggest to place the initiating node as the last-created node on the last (rightmost) tab, and use a link out to send the on-start message to its destination.

6

Or simply wait ten seconds or so after startup to send your message. That's how mine is setup and seems to be reliable.

7

node.send({ payload: "Started" });

This is what I was looking to do. Thanks!

8

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