Node-RED FAQ

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How can I work under Node-RED and "sudo" authorization?

Take a look at the steps of this discussion:

I want to run "piTest" on Node-RED and get errors, what can I do?

Take a look at the steps of this discussion:

I have problems with the touchscreen accuracy when I use the Node-RED dashboard, what can I do?

(661) [Node-RED] Chromium not displaying Flowfuse chart - The Industrial Raspberry Pi Forum (revolutionpi.com)

I get a "Proxy Error" when I click deploy, what can I do?

To test whether the proxy is causing a problem, the sytemd unit file in which Node-RED is bound to localhost can be adapted:

The "ExecStart" command must be adapted there, which binds Node-RED directly to a port and localhost.

After editing this file, either restart the system or execute the following commands:

Node-RED can now be reached from outside via port 1881.

Please do not switch to port 1880, the apache2 proxy also runs on this port with a forwarding to port 41880. The "revpi-nodered-proxy-apache" package must only be uninstalled if the proxy is to be removed completely:

I am trying to install the node-red-node-serialport extension. Unfortunately, it does not work via the menu in Node-RED or via other ways, e.g. the bash, what can I do?

Carry out the steps in the following checklist: Node-RED Checklist

Original discussion:

I was wondering if there is any type of module state detection for add-on modules in Node-RED?

How can I query the digital input of the RevPi Connect 4 in Node-RED?

I want to access Oracle databases from Node-RED and wonder if this is possible?

I want to use Node-Red to receive data from codesys via Modbus TCP and then send to the cloud using MQTT. How can I convert Node-Red Double Word to 32 bit LIN?

Please have a look here: (58) Node-Red Double Word to 32 bit INT Conversion – Revolution Pi Forum

I have variables saved on context file System, but if I restart the RevPi (sudo reboot) the variables are kept. Conversely, if the device is turned off by removing the power supply, the variables are not maintained. How can I overcome this?

Please have a look here: contextData on fileSystem - Revolution Pi Forum

Update from Node-RED not possible, and I use Epiphany browser, what can I do?

As a first workaround: you can try using a different browser, the standard browser (epiphany-browser) on the RevPi is a bit limited. My recommendation would be using Chrome or Firefox from a different computer on the same network, then calling, e.g. http://192.168.1.100:1880.

https://revolutionpi.de/forum/viewtopic.php?f=6&t=2580

I got an error message “noderedrevpinodes-server.service is a disabled or a static unit, not starting it”, what can I do?

Open

The revpinodes server has been disabled. Remedy as follows:

The first step should not be necessary, but is listed for security (in case the service was masked). Masked services cannot be enabled with enable even during a new installation, and it must be done explicitly via the command.

I think I have a memory leak problem with Node-RED, is this possible, and what can I do?

Yes, there is a known problem, but it has been fixed with the latest version see here:

https://github.com/erminas/node-red-contrib-revpi-nodes

Perform the following checklist to fix the error:

Node-RED Checklist

I use IO modules and have issues accessing them via Node-RED. Are there any idea?

So that the “noderedrevpinodes-server” can run, it accesses the file that you have created before in the PiCtory.

And this file you have to save not only “save as” but as start file:“"save as start config”".

Then I updated my nodes to the latest version and suddenly, it worked.

https://revolutionpi.de/forum/viewtopic.php?t=3391

The RevPi nodes (RevPi single input, RevPi multiple input etc.) in Node-RED remain in a disconnected state after a reboot.

This issue has been resolved.

https://revolutionpi.de/forum/viewtopic.php?f=6&t=3000#p11361

I am not using the current distribution but Jessie and I want to upgrade to Node-RED, how do I do that?

No, unfortunately this does not work, please upgrade your system, see here:

https://revolutionpi.de/forum/viewtopic.php?f=48&t=2967#p10615

Is it possible to access the Modbus RTU interface on the RevPi Connect directly from Node-RED without having to set up a virtual Modbus master in PiCtory?

The“"RevPi wa”" is with PiCtory, but of course, it is up to you to try another way, maybe with Modbus or something else.

Here is the original discussion, so in case you have ideas you want to share, just post your ideas here:

https://revolution.kunbus.de/forum/viewtopic.php?f=48&t=2999#p10742

I want to create an HMI on a 5-inch display, can I do that with Node-RED, and where do I start?

The best place to start is with the following video tutorials:

• https://revolution.kunbus.com/tutorials/video-tutorials/?noredirect=en_US#VT26

• https://revolution.kunbus.com/tutorials/video-tutorials/?noredirect=en_US#VT27

Together with the RevPi Nodes, you can create a Responsive HTML5 HMI in no time without even knowing it.

I notice latencies of 5 seconds between action and reaction. However, when I use piTest everything works in real time – what can I do?

• https://revolution.kunbus.de/forum/viewtopic.php?f=48&t=2787&p=10548#p10156

• Restructure your Node-Red code and split it into multiple flows.

I can't find a way that, the Node Red UI that I created, starts automatically when the RevPi starts.

For this, we have a possible solution in our forum, which you still need to translate from German to English. I recommend DeepL for this.
https://revolutionpi.de/forum/viewtopic.php?f=47&t=3330

I want to use Node-RED on my RevPi, but how?

Have a look at our Video Tutorials

https://revolution.kunbus.com/tutorials/video-tutorials/#VT26

https://revolution.kunbus.com/tutorials/video-tutorials/#VT27

I want to write input values to visualize things. How can I do that?

https://revolutionpi.de/forum/viewtopic.php?f=47&t=3036#p10873

I have problems with node-red-contrib-revpi-nodes broke host field in TCP in/out

Have a look at this forum entry:
https://revolutionpi.com/forum/viewtopic.php?p=14244#p14244

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