Car Video Interface for Mercedes-Benz E-Class (W211)

Hi,
I just received the interface that I have bought you.
Now, I'm installing the unit in the car of my brother and I have a doubt.
From the power connector, the orange wire titled I-Drive, Where do I connect it?
To the positive pole of the battery (before or after the ignition key)? Or, In another place? ...
Plaease, help me.
B.R.
I just received the interface that I have bought you.

Now, I'm installing the unit in the car of my brother and I have a doubt.

From the power connector, the orange wire titled I-Drive, Where do I connect it?
To the positive pole of the battery (before or after the ignition key)? Or, In another place? ...

Plaease, help me.
B.R.