Define elevator status:
{
STAND_BY,
MOVE_UP,
MOVE_DOWN
}




Define variables
ElevatorStatus = STAND_BY;
Running = true;
CurrentLevel = 1;
GotoLevel = 2;
TriggerElevator = true;




LOOP(Running = true)
{
IF( ElevatorStatus = STAND_BY)
{
IF (TriggerElevator = true)
IF ( CurrentLevel GotoLevel)
ElevatorStatus = MOVA_DOWN;
}
}

Noticed IF (CurrentLevel = GotoLevel) Elevator need not to move either up or down.