To send commands over RS-232 from a LG WP400 or LG WP401 to an external monitor you'll need the following:

• An RS-232 (mini jack) to whatever RS-232 input the external monitor has (possibly mini jack or D-SUB)

Then, set this up as follows:

1. Put the mini jack RS-232 cable in the RS-232C IN port on the LG LG WP400 or LG WP401. This is the BLACK mini jack port, next to the mini jack IR port. 
   Note: do NOT use the green RS-232 OUT port
2. Open the GoBright View Portal
   
   1. Go to the Device tab
   2. Open the device
   3. Under External devices, click the little + button or edit the current values 
   4. Set COM port to 1 (without any prefix)
   5. Set the other values to what the external monitor can understand (refer to the manual of the external monitor)
   6. Click Save
   7. Click Update configuration