Thanks for the reply, @ZefTheFox.
Your idea sounds neat, but It would require me to rewrite my whole program. Probably doable, but I would like to keep it as it is, as I have tested it and it works.
However, your reply did make me do some digging, so I looked a bit closer at the API.
The way my program is written right now, I think I can get away with using only one card. At startup the program listens for the first signal. When it receives the signal, it jumps into a loop until it receives another signal.
The trouble I'm having is that I can't figure out how to use the red