I have a few LG 55SE3D-BE commercial digital signage displays that I would like to control with the Brightsign LS424 player. I have the USB C to 3.5mm serial cable (from Brightsign) and I have a 4 conductor 3.5mm cable going from the Brightsign player to the 3.5mm RS-232 IN port on the back of the LG Display (the LG came with a 4 conductor 3.5mm to DB9 adapter, so I went with 4 conductor 3.5mm). I setup a Bright Author project with a Time/Clock event set to Send Serial String (EOL) Port 0 with the string "ka 01 00" (not including quotes). I found that command on this site and it should power off the display. Other sites that I've found indicate this command is correct, however, it does not seem to work. I tried using the same event to send Video Enable monitor power save mode and that works, so I'm fairly certain I've got the scheduling side right. Based on this LG manual (page 64) for a different model, I've set the Baud rate to 9600 and other settings in Presentation Properties > Interactive. LG says you need a crossed cable. In properties there's an option for Invert Signal and I tried that as well.
Any suggestions as to what I might be doing wrong or how I could go about troubleshooting this?