Steppers & Linear encoders

Adding a 7I84 will not be helpful

To add encoder feedback you would start with a plain 7i96 configuration
and then add the encoder setup in the hal file and encoder scaling in the
ini file. Then you would change the position feedback source from the stepgen
to the encoder.

To do this you should start with a working open loop stepper system

Have a look at this thread:
forum.linuxcnc.org/49-basic-configuratio...-loop-setup?start=20

I think Hakan is using the same board setup that you are and he has posted his HAL and INI files. You should be able to see the required "loadrt hm2_eth_board_ip=" line that pics the needed firmware and associated parameters.

I have not gotten to the ethernet side of things myself. I'm still using PCI based kit.

Cheers.