I'm trying to create a pattern feature wich includes a measurement (minimum distance) between 2 faces, I'm using this measurement as reference for another feature (move face or pattern geometry), so this measurement should change along the whole pattern, but when I run the pattern feature what I get is that the measurement never changes (like if it was a constant value).
What can I do to make this measurement to change in each instance of the whole pattern?
When you create the measurement, make sure the Associative checkbox is turned on.
You should see the measurement in the Measurements folder.
It seems that not all measurements create this associative measurement.
To use the expression, notice the "p number" name of the expression.
You can see this in Tools, Expressions, or by selecting the measurement in the Part Navigator, and look in the Details panel.
Enter this expression name, such as p23 where you want to use the measurement.
An associative measurement is a timestamped feature. A feature with a later timestamp (e.g. a move face or pattern that uses the measurement for input) cannot change the value of the measurement (if that were possible, you could run into circular reference errors or infinite loops).