Allowed by FMCSA explicit scenarios (each of them loaded or not, NO LIMIT on distance and you can't be fatigued or ill):
1. When you're off duty (part of 10 or 34 hr break) go to a restaurant or entertainment (including at a truck stop). This rule can be used universally for all PCs.
2. From company Terminal or Trailer Drop Lot to your home (and back if you'd like to or you can stay at home). For Trailer Drop Lot you need to show that you changed trailers there (or dropped one or picked up one). No particular definition for Trailer Drop lot.
3. After you loaded/unloaded at shipper or receiver to the closest safe location. If you come to the closest one and it's full - make picture/video that it's full and then go the next closest one. You cannot go to your home.
4. Any time a Safety Official tells you to move. Cops, Security Guards and other safety officials qualify.
Each time you use PC you have to put notes in your logs.