I have no experience with the Denon DN-V310 but I do program Pronto remotes.I have read the Serial Protocol Manual found here,[Link: d-mpro.com]
It does not have discrete ON or OFF codes listed,but what you could try is replacing the RC codes (decimal) for the command from 0 to 255 which should give you all possible RC codes for the remote.
[PC, RC, 10]\r
[PC, RC, 11]\r
[PC, RC, 13]\r
[PC, RC, 14]\r
and so on.
Just eliminate the code digits that the Serial Protocol Manual already lists.
If you do not find the Power ON and OFF discrete may not exist for this model.
What are you using to control the DN-V310?