How to receive LVDS signals from ADC?

Open your project, then open the Pin Planner. In the cell containing <new node> enter a new group name for your differential signals, say D[13..0]. Pin Planner will add the 14 signals for you in a separate row each. Then in the IO standard column set it to LVDS. The Pin Planner will now create the complement pin for that signal -> D[*](n). If you later place the positive pin on a (valid) location in the pin diagram it will nicely take the complement signal along and place that as well. In your logic you just connect the D[*] pins in your entity.