PG is called pulse generator, which is short for pulse generator. Usually used to measure rotational speed. For example, photoelectric encoder is a kind of PG. PG card in frequency converter is a part of vector frequency converter, which can convert and isolate the signals of encoders with different output forms, and output signals that can adapt to the controller. It mainly includes: level conversion, analog-to-digital conversion, optical coupling isolation, shaping and so on.