Nodered feedback connection

how can I tell if the device that I connected to nodered has blocked or is not sending data anymore or does not respond to the command?

you can use Online/Offline trigger to send notification when the device becomes offline.

I’ll explain. when I insert the mqtt server in nodered to receive the values. they don’t know if it’s online or not

I look for a way to understand if the arduino that transmits freezes / disables / does not transmit anymore

how can I do?

@adam any idea on how to do this?

I was thinking of trying if nodered does this check back through some function in mqtt or come up with something with a counter + time, but I don’t have the basic knowledge to produce that

I don’t understand the question. Are you trying to tell if a device that you have connected to a local MQTT server through node-red is disconnected, or if the local MQTT server that is connected to Cayenne is disconnected?

do you know with the cayenne library when the device is not connected inhibits the writing ?!
here I would like that with nodered when with the library esppublishing the device does not transmit anymore or turns off it warned me

i am not able to understand what exactly you want. @adam do you get what he is trying to say?

Still not super clear for me either. My guess is that the offline trigger will work for him. @shramik_salgaonkar Does that now work with MQTT? I remember a while back that was a Pi agent only feature.

it works for MQTT device also.

i have already suggested him this but he wanst something else.

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provo a spiegarmi in italiano.
quando collego un dispositivo tramite la proceduta pubsub a nodered, e poi a cayenne, dato che nodered fa risultare il dispositivo sempre online, come faccio a capire se il dispositivo non lo è piu, provo a mandare una foto per capirci
il dispositivo “veranda temperatura” collegato con la procedura pubsub sarò sempre connesso anche se non funziona,
il dispositivo “veranda” collegato a cayenne farò risultare sempre online e i dati inviati.
come posso far capire a cayenne e a nodered che il dispositivo “veranda temperatura” non invia piu?!

For that you would use the will message:

Here is a description of it Last Will and Testament - MQTT Essentials: Part 9

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l’unica cosa che mi manda arduino a nodered è questi valori. non ho la piu pallida idea di come far mandare un messaggio per la disconnessione

you mean you want the arduino to send an disconnect message to the node-red?


well, you can start a timer on node-red, and check if it greater then 15 sec (default publish time). If yes, then register it as disconnect.

That’s exactly what the will message does. Just set it up and test it.


@adam will guide you best here.

I gave you an example above. Open the MQTT in node. click the pencil to edit the server settings, go to messages, then put in whatever you want to be sent when the server detects the disconnect.