Serial && status node on boot / start

#1

On boot of my raspberry and node red i want to know if my serial port is connected to my arduino.
So i connected the status node to the serial port and to mqtt, but no output
Then i connected the debug to the status node to see if i get feedback on boot but also no result.
If i pull later my usb from the board i get an output.
So it works but not on boot :frowning:
Is there a way to get the node status on boot?

Thanks
Rogier

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#2

You will only get output if whatever the serial port is connected to actually sends you something.

If Node-RED cannot connect to a serial port on startup, it will give an error in the log.

If you are on a LINUX based machine, you can check the status of a serial port using dmesg - I think there should also be something on one of the /proc pseudo folders but you'd have to look that up I'm afraid. On Windows there should also be a command - probably part of wmic - but it escapes me off the top of my head.

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#3

Its on a linux machine, i will try to fix it with that thanks.
But the node has a status on boot like connected if the arduino is connected
Was hoping that i could use that message

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#4

If your serial node is showing the status message "connected", you can simple use a status node to look for that message, and trigger another flow whenever it changes... is this what you are looking for?

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#5

Exactly that is what i did. But that only works after starting NR
So if NR is running and the status changes it works.
But when it starts the first status is not transmitted

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#6

Well ... it is transmitted... but at start time - as node.js is asynchronous - the actual start order and timing of all the nodes is not 100% deterministic (although tab one generally gets started before tab 2 etc) - so the message has probably been and gone before the status node is ready.

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#7

ok clear, should it be possible to save it to a flow variable?
or is there any other solution to get the status?

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