Thank you for web link :-)
Atari 520ST Language Disk (520LANG.ZIP) helps me with connection to PC through nul-modem cable and Ghostlink. Actualy I don't need to ajust anything. I leave all settings in RS232 configuration as is (default) but Ghostlink doesn't work without it ("**** Master error ****" on PC side).
This open a new dimension with Atari 520ST use to me, because I haven't a HD for Atari. Ghostlink isn't much useful because it can't run PRG file from PC hard disk, but I can read TXT files and copy files to my real Atari SF354 floppy.
BTW, exist any software for Atari 520ST which can make a RAM disk?