Rover Pixhawk 2.1 encoder

I have 4 motors each motor have its own encoder, is it possible to use pixhawk 2.1 to get reading from 4 encoders? If yes, any documentation would be great, if not? is there a way to do it

Only 2 encoders are supported at this time, see https://ardupilot.org/rover/docs/wheel-encoder.html for setup details.