Hi,
You need to use amplitude and assign it to your boundary condition.
In inputdeck the keyword will be look following:
...
*AMPLITUDE, NAME=move-XY
0.0, 0.0, 1.0, 1.0
*BOUNDARY, TYPE=DISPLACEMENT, AMPLITUDE=move-XY
node_id_to_move, 1, -200.0
...
Regards,
Bartosz