Hi Nadja,
once you connected the RFID reader to the widget you should be able to read out the codes with the RFID script node. The helpfile gives you a pretty good overview on it:
http://www.coolux.de/root/downloads/sup ... cripts.htmIf you use the ID to trigger something you do not necessarily need variables. You could change a set variable using a script. There are several scripts dealing with variables, the all start with a V. So if you type v in the script node it will offer you those.
Some general information about variables can be found here:
http://www.coolux.de/root/downloads/sup ... iables.htmTo trigger something on release is not possible in my understanding. The reader does not make a difference in getting or loosing an ID. So it will only display the ID os long as it can see the ID.
best regards
Patrick