Read USB keyboard or RFC reader connected to USB at the Raspi

Hardware
1

I want to read a RFC tag with a RFC reader connected to my Raspberry Pi via USB.
It acts like a keyboard with a 10-digit output on the active tty.
How do I read that input with Node-RED?
I saw a post on a Siemens forum, but that did not help me:
https://support.industry.siemens.com/tf/WW/en/posts/usb-keyboard-and-node-red/164793?page=0
I don't want to use the RPI keyboard node which scans only single keypresses with up and down, but return one single string as msg.payload.

2

Have you tried the serial in node?

3

I have found a solution:

#!/bin/sh
# start only when called from the console
if [ ! "$TERM" = "linux" ] ; then
exit 0
fi

ok=false
while [ $ok = false ]
do
read choice
case $choice in
	123456789) sudo init 0
	;;
	*) echo `date +%Y-%m-%d_%H:%M:%S`: $choice>>/home/pi/keyboard-archive.txt
	   echo $choice>/run/user/1000/keyboard.txt
	;;
esac
done

I start the bash script from ~/.bashrc (last command)

In Node-RED I check for changes in the archive via the watch node and read the content of the keyboard.txt via the file in node, because the watch node has this...

Note: The directory or file must exist in order to be watched. If the file or directory gets deleted it may no longer be monitored even if it gets re-created.

To prevent massive SD card writes, the archive file could also be stored in /run/user/1000/ (tempfs)

When the transponder with the number 123456789 is read, the raspi will shutdown.

4

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