Steen:
yes, this is perfectly possible. The only thing you have to keep in mind is the number of pins you have. If you do not use driver chips (so you have to wire up every led yourself through multiplexing) the it might get hard, but if you use a such a chip, it can be easely done.
Hey, thanks for fast reply.
Further question. I use LED RGB strips as you can see in the link below. So the wiring effort is not the problem. Is it possible that you give me a short (really short) overview of the code needed to do this "programm control". The problem is all my contacted suppliers for RGB LED strips say that it is not possible to set up an Arduino lik eI want. I think like you do "it can be done". Confusing thing.
// Edit:
Sorry Nick for double posting, wont happen again. I search for about 1 Week to fix that problem. Try tu use the keywords on google "Arduino and PLC" you will get only none specific answeres.