3.2.1. Assigning to Exclusive Pin Groups
You can designate groups of pins for exclusive assignment. When you assign pins to an Exclusive I/O Group, the Fitter does not place the signals in the same I/O bank with any other exclusive I/O group. For example, if you have a set of signals assigned exclusively to group_a, and another set of signals assigned to group_b, the Fitter ensures placement of each group in different I/O banks.