I need some help with using serial commands on the d64u. I have been trying to send some commands and nothing seems to be working.

This is a newer series than the d92u series that had the firmware upgrade to enable serial control, and I'm not aware of any firmwares for this series.

These are some of the things I've tried:
-using the CM232 directly and also with a null-modem (cross-over) adapter;
-gone into the Service Menu and have not seen any option for "StandBy Type 0;"
-tried using the RSPW1 command to turn on the ON/OFF serial control;
-and checked that I am outputting to the correct port.

The commands I'm using are directly from the user manual:
"RSPW1 /r" to enable ON/OFF serial control;
"POWR1 /r" for ON;
"POWR0 /r" for OFF;
"IAVD1 /r" for INPUT 1;
"IAVD2 /r" for INPUT 2, etc.;

Any idea what I might be missing?

Thanks,
CJ