Since you know the checksum for HDMI1 is \xC7, just reduce that for each increment - HDMI2's checksum would be \xC6. Skipping the header & checksum, HDMI inputs go in order:

\x100-\x2C = \xD4, which is what you find at the end of the command below. The codes are all outlined in the spreadsheet.ĮVERY command needs to be prefixed with \x08\x22.ĮVERY command needs a checksum byte that you can determine by adding up all the bytes in the command (including the two header bytes) and subtracting it from \x100. In the documents area of the file section, it's 'Samsung RS232_2008