If the linear-encoder position of the undulator drifted during stand-by, the feed-back system corrects this before the gap move begins (init sequence). Therefore a wake-up call that moves the undulator to the start position of a scan is advised. The wake-up call should be a move greater than 4 microns. Otherwise the undulator sees no need to act and does not execute the init sequence.
Normal moves (aka non-scan moves) can be issued without any wake-out calls.
If the current position of the undulator differs by more that 4 micron from the setpoint, the undulator exits the stand-by state and corrects the position. Experience shows that this happens only after a restart of the accelerator.