Located in the Ladder toolbox under Basic Elements, these Ladder elements pass on the RLO of a rung--without being linked to a tag:
The Up element assigns TRUE to the output signal Out for one cycle only when the input signal In changes to TRUE. Otherwise, the value of Out is FALSE.
The Down element assigns TRUE to the output signal Out for one task period only when the input signal In changes to FALSE. Otherwise, the value of Out is FALSE