Thanks for the response, Dave.

I did add the codes into the Hex field.

I created a new button, opened it, clicked on the first tab (Action?), named, the button, set the fields to match those specified in the Toshiba protocol, set it to port 2 (which is the port to which the HD DVD player is connected) and entered the different permutations of the code I listed in previous posts into the Hex field.

When I press the button, the green LEDs for Busy and Serial Port 2 both light, but, nothing happens, and no errors appear in the logs.

The Toshiba serial protocol states that pin 2 is receive, pin 3 is transmit and pin 5 is ground. I can't find the pinout for the RFX9600 in the documentation or on this board (does anyone know what this is or where I can find it?), but, the Phoenix connector, from left-to-right, is Tx, Rx, Gnd. Seems like a reasonable assumption that the DB9 ports are similarly configured, such that pin 2 would be transmit, pin 3 would be receive and pin 5 would be ground. If this assumption is correct, pin 2 on the RFX (Tx) should be connected to pin 2 on the HD DVD player, and so on. In any case, I've tried switching them around.