I Installed 2 linear scales on my CNC ROUTER, but I have a question:

1- The Linear Scale works on close loop with MACH3?, feeding the MACH3 and making the movements more accurated. Or the Linear Scale is just for show the position.

Danial
 Mach is not closed loop. You can get a board that will interface with your linear scales and provide out of position feedback to Mach but this will only tell Mach to stop, not try and correct the positional error.
Hood