I was able to use the predefined TV control for a Cisco 32N display to turn the LG display on and off. I did however need to create a custom command for switching to and from the HDMI and cable IN. The hex commands for those are below.
rs232.tx_hex=6b622030312030300D
rs232.tx_hex=6b622030312030320D
Your commands look very similar so I will assume they are correct.
Did you run the 'RS-232: Control supported, non-DMTech display' advanced task on the DMP prior to this command?
After running the on command, run a status on the DMP in question, look for the lines starting with rs232 and see what the rs232.tx_hex is set to, should be your on command regardless of if it worked or not. I usually copy the status result to a notepad, easier to look through and your can use the find command.
Good luck
