You can place and move logic by hand.
- If the cell is already placed, drag and drop it to a new location.
- If the cell is unplaced:
- Click the Drag & Drop Modes toolbar button and select Create BEL Constraint Mode.
- Drag the logic from the Netlist window, or from the Timing Report
window, onto the Device window.
The logic snaps to a new legal location.
Tip: When dragging logic to a location in the Device Window, the GUI allows you to drop the logic only on legal locations. If the location is illegal (for example, because of control set restriction for Slice FFs), the logic does not "snap" to the new location in the Device view, and it cannot be assigned.
Hand-placing logic can be slow, and used in specific situations only. The constraints are fragile with respect to design changes because the cell name is used in the constraint.