Good day learned ones! I have a need to be able to set a serial port address from an defined variable that I can input via a dashboard.... Particularly these bits (particularly the Port Address, More if possible....) [screenshot-192.168.0.118_1880-2021.06.07-10_45_26] I am not sure whether it is…

No but if you want to change the input make a flow with a switch that looks to a global variable. And connect all devices on a seperate input node, but let the switch only pass the ones that are selected based on the value of the global variable.

You might be able to set the port using an env variable but I dont think the other values can be set dynamically. To use an env var in a config var, see Using environment variables : Node-RED

Thanks Steve, I will go through it and give it a go! Much appreciated!! Ed

Where I am curious about is, what is the case between it? Maybe you can change your approach and instead of port select the serial device by ID. See /dev/serial/by-id in your linux machine.

Hi @EmilWesselink I was previously using by-path, so it should work to use by-id - I just need to wrap my head around selecting this setting from a dashboard and seeing if it can be done... E

@EmilWesselink Ah, got you! - in my "simple terms" - set up a bunch of "default" configuration serial nodes referring to usb0/usb1/usb2 etc and just limit/enable the comms to those nodes via "switch control" ..... that might just work for me!! Tnx E Edit: I would rather go the "port" route than …

@EmilWesselink Here's the "alternative solution" I have settled on, thanks for the pointer into this direction! [screenshot-192.168.0.118_1880-2021.06.07-16_22_04] Depending on a global variable written to disk in the parameters, the switch nodes only allow writing to a particular usb port and re…

If you only ever have one serial usb device plugged in the you could use a udev rule to map any serial device plugged in to a fixed virtual device to, for example, /dev/serial. Configure node red to use that device and it should work with any device. you might even be able to hot plug them, I am n…

Wont work for me.... Multiple devices, but might help someone else indeed! But interestingly, regarding the hotplugging, I don't think it will... It seems that while an i/o can be pointed to the correct usb while "live", Node Red doesn't seem to pick it up until it is restarted with the device in p…

How does one set a "parameter" via a global variable

General

EmilWesselink 7 June 2021 13:48 8

That is exactly why I asked you to give some more information about what en why you to achieve something. It can give people more insight to have a alternative solution. For me the id was the best solution because the device in was always the same, only the port changed sometimes.

Topic		Replies	Views
Custom serial node General	0	467	25 October 2019
Node-red-serial port port selection General node-red-node-serialport	7	517	16 March 2025
Serial port modifications General	2	198	29 September 2023
Change Serial COM Port from webpage General uibuilder	7	297	5 April 2023
Env variable at runtime? General	7	213	4 October 2023

How does one set a "parameter" via a global variable

Related topics