Question about PetSafe Petporte Smart Flap

No, that is not possible. The best way is to follow the assembly instructions (as described) step by step: Temporarily assemble the cat flap (without flap!), read in the cats (we did this on the floor with treats, because it doesn't always work immediately with the chip reading, then they could always go through the door again), then install at the final location (door, window), and only at the very end (when everything works) connect the battery. The chip reader does not work with battery operation alone! Good luck :-).