Thank You Richard for helping me. That's great, now the "core" of my distance meter works perfectly. Yes, the max. distance what I can measure is near six and a half meter which is enough for me. If I want to measure more than 6,5m simply zeroed the reading and start count from that point. Now I must implement negative reading when I go to opposite direction from zero the reading must be from -1..... to -655,3.
Your explanation helping me a lot, once again Thank You.