CONNECTION LOST dashboard error every 30 seconds

[wa9mvz]

Running Node-Red on a Pi 3B and Chromium browser.

I am receiving external serial data from a SERIAL IN node and doing some arithmetic on the payload. Everything works flawlessly according to the debug nodes in the flow and it works fine when I initially switch to the dashboard to view the results.

But almost exactly every 30 seconds the dashboard view flashes the error "CONNECTION LOST". Everything reconnects in a second or two and all is well until after another 30 seconds when the behavior repeats.

Can anyone help me fix this?

Fred

[vikozo]

have you some information in the Log file of the Raspian/Debian? Or what do show a top command?

[wa9mvz]

I'm sorry, but I don't know how to access that

[hotNipi]

What are the things you are presenting on your dashboard? Make a screenshot ..

[vikozo]

command Line of your Pi ?

cd /var/log
tail syslog

maybe there is something wrong

or just enter top in the comandline maybe you see something when it lost conection

[wa9mvz]

The dashboard is fairly simple. The serial data comes in fairly quickly (every 250mS or so) and as I said it appears to be working in the flow.

[hotNipi]

Try to limit the data rate on the flows before the nodes of dashboard widgets. See if that helps.
Use the delay node like this.

[wa9mvz]

I tried a delay in several locations. No joy.

[Paul-Reed]

Try stopping node-RED - node-red-stop and restart again node-red-start and watch the log.
You will probably see the point where node-RED stops & restarts, so copy the log, and paste it here so we can see what's happening.

[wa9mvz]

Nothing pops up when the disconnect appears and the startup seems to be normal. I did notice that this only happens when I have the GAUGE in the group "COLUMN 2: active. Something about that is affecting this

29 Jan 14:19:29 - [info] Linux 4.19.118-v7+ arm LE

29 Jan 14:19:31 - [info] Loading palette nodes

29 Jan 14:19:37 - [info] Dashboard version 2.27.0 started at /ui

29 Jan 14:19:37 - [info] Settings file : /home/pi/.node-red/settings.js

29 Jan 14:19:37 - [info] Context store : 'default' [module=memory]

29 Jan 14:19:37 - [info] User directory : /home/pi/.node-red

29 Jan 14:19:37 - [warn] Projects disabled : editorTheme.projects.enabled=false

29 Jan 14:19:37 - [info] Flows file : /home/pi/.node-red/flows_raspberrypi.json

29 Jan 14:19:37 - [info] Server now running at http://127.0.0.1:1880/

29 Jan 14:19:37 - [warn]

---------------------------------------------------------------------

Your flow credentials file is encrypted using a system-generated key.

If the system-generated key is lost for any reason, your credentials

file will not be recoverable, you will have to delete it and re-enter

your credentials.

You should set your own key using the 'credentialSecret' option in

your settings file. Node-RED will then re-encrypt your credentials

file using your chosen key the next time you deploy a change.

---------------------------------------------------------------------

29 Jan 14:19:37 - [info] Starting flows

29 Jan 14:19:38 - [info] Started flows

29 Jan 14:19:38 - [info] serial port /dev/ttyAMA0 opened at 115200 baud 8N1

[wa9mvz]

There seems to be a speed limit to how fast the GAUGE node can update and I was apparently exceeding that limit. When I limit the number of decimals coming into GAUGE to 2 instead of 3, it updates more slowly and the CONNECTION crash goes away.

Thanks for the responses.

[hotNipi]

Any widget with animations involved will make high rate updates very hard to handle. It is not possible to turn off the animations for ui_gauge node but you can use the artless-gauge with animations turned off. But anyway, updating the gauge with high rate makes it pretty unreadable. So rate limit is reasonable thing to do.

[Colin]

I imagine the main problem is running the browser on a pi3 with the node red dashboard and fairly rapid refresh rates. A pi 3 is barely powerful enough for that. You would have a much better experience if you upgraded to a pi 4.