Setting variables in read-only mode

Hello,
I want to make some parameter to read-only mode or constant. So that no one can change the value of that parameter using gcs.
I used APJ Tool, even I tried by using @READONLY flag in code.
But its not worked for me.
Is there any way to make it possible by changing code.

Parameters that i want to make read-only:

  • FENCE_ALT_MAX
  • FENCE_CIRCLE_RADIUS