This VB example displays the block ID of each frame in a text box.
Private Sub ActiveUSB1_FrameAcquired()
Label1.Caption = ActiveUSB1.GetBlockId
Block ID is an ordinal number (starting from 1) assigned by the camera to each acquired frame. Block IDs can be used to identify missing frames.
If this method is used in the FrameAcquired event handler, it must be called immediately after the event has been received. This will guarantee that the value of the block ID will not be taken from the next frame while the current frame is being processed.