Is there any way to save ST7 part files as ST6 part? (I have not found that option myself). I need this because I have ST6 and it can't open ST7 files I receive from others. Or a more general question, how can ST6 open an ST7 file?
Solid Edge files are not backwards compatible and there is no function or utility to save them back to a prior version. The only way to utilize a Solid Edge ST7 model in ST6 is to save to a neutral Parasolid file (recommended) or a translated files such as IGES or STEP. Watch the Parasolid version because ST7 may generate a newer Parasolid version than what ST6 can read. Drawings have to be saved out as DWG/DXF to be translated back in.