I post a coment on the wrong place, and was encourage to do it here. Sorry for the noise.
After a few tries I’ve been able to read the chip ot my 3 cats. We have a high-tech-very-expensive feeder that activates reading the chip of the correct cat. Now I can open the feeder emulating the chip.
The feeder is a sure petcare. It comes with a EM4100 little medal in case your cat does not have chip. And my cats chips are FDX-B chips.
Sometimes is difficult to include a specific pet in this kind of devices, because you need, well… your pet colaboration. Is easier to read & emulate.
And here in spain there is a registry with chip numbers that has info like owner’s phone, name… If I find a lost pet I can read the chip and contact the owner quickly.