With the help of a knowledgeable guy over at the MainLobby (Cinemar) forum, I was able to figure out how to send discrete commands to the Outlaw in hexidecimal. The trick was in figuring out how to add the "checksum" at the end of each command line.

For example:

Power On is 83 45 01 C9 in hex, where 83 45 is the system ID and precedes every command. 01 is the "power on" command, and C9 is the checksum.

To calculate the checksum, you convert each hex value to its decimal equivalent and add them up, and then express the sum in hex.

This gives you 131+69+1 = 201.

201 in hex is C9.

So the command is written 83 45 01 C9.

For standby, it would 83 45 02 with a checksum of CA (202 in hex).

For "Tuner" input select, it would 83 45 03 CB.

If you have a terminal program, or any other type of program (such as the Girder serial plugin) that can send hex to the serial port, then you can send discrete commands directly to the 990.

IMO, serial control is infinitely more robust than IR control.

The next challenge is to figure out how to work with the data being returned by the 990 through its serial port. This will allow your control device (Creston, AMX, HTPC with MainLobby, etc.) to know the state of the unit, regardless of whether the unit's state has been changed by a sent command, the remote, or by someone turning the dial. It allows cool things like displaying the current volume level on your touchscreen controllers . .. .

If there's interest, let me know .. . .