Your code is not complete! You have a nice lookup table but you do not use the outcome from the table? Where do you use the variable Segments? Is Digits the name of your port? (which you imply when you set it = $FF at one point)

Also, the way you have it (Digits =~DCD i)
Digits can only be

11111110
11111101
11111011
11110111

Although it is late here, your code makes no sense to me

However, if Digits does control the port, it looks like you can turn your DP on by issuing this
Digits.7 = 0
(provided the wire or trace from the DP goes to pin 7 of your port).

Post complete code for better shot at guessing what you are trying to do.