Thanks
Dear Hero999, 2963 posts, 8.7 posts per day. All your posts are so interesting as your reply to this thread?. I can see thousands of things to do with 24 years of age more interesting than this. In any case, yes, I meant a Programmable Logic Controller.
3v0: Thank you very much for your answer. The wires are +- 30 meters long. Is it too long?
mroberts: The valves are on while they receive voltage. I think that my main problem is that the valves work with AC. If not, I could use the polarity with respect to ground to send 4 different signals (++, +-, -+, --) using only two wires. At the valves end, with diodes, I could send the signal to the correct valve.
Thank you