DBPlannerDatePicker - enter Time

We need to enter Date TImes (must be nullable so regular datetime components aren't an option). TDBPlannerDatePicker works great for the Date. Is there a way to allow the Time entry with the same component?
Under the property Calendar are the fields EndTimeFIeld an StartTimeField, what are they for and how are they used?

Can you suggest another db component that allows date and time which allows null datetime?

Thank you,

Sorry, unfortunately TDBPlannerDatePicker is for date entry only.

At this time, the only DB component for both date & time entry is TDBAdvDateTimePicker, but unfortunately, this has no support for nullable dates.
StartTimeField/EndTimeField are used to set fields of the connected dataset that hold start & end dates for events that can then be visualized on the calendar.