It's NOT safe to use SEMC Tool 8.4 free. Many people have transformed their W810i into a brick by using this tool. USB-Smart dongle has not come out for nothing. When I unlocked my W810i I used USB-Smart dongle and SEMC Tool 8.7.
However, I have on my PC both 8.4 Free and 8.7 versions, I will post them later, I am at work right now.
Again, I do not recomend the 8.4 free version, or, at least, try not to attempt to read all codes using Cruiser 4-in-1 and 8.4 free version :)