The CV Change Gate module monitors a control voltage and generates a trigger when the CV changes. There are controls for the sensitivity (how much it has to change) as well as ranges where the trigger is monitored; these can both be set as Voltages or as notes/semitones. When the minimum change is non-zero, you can have the trigger on changes between states, or changes since the last-changed state.
This module can be used to, for example, generate accents or additional notes on changes to a note – especially useful with sequencing which may have a note repeating with occasional change of pitch. For ease of use, the input defaults to using the Pitch panel CV Input but can be overridden by jacks.