my mac pro with OS x.11.6 goes to sleep even with the energy saver set to never
my mac pro with OS x.11.6 goes to sleep even with the energy saver set
  to never


With OS X 11.6 the Caffeinate command in Terminal should work and keep it awake.

Open Terminal in Utility Folder and type Caffeinate.

If you want to investigate what is putting it to sleep, open the Console in Utility folder and look at the lines before it goes to sleep (or post it in you post).