serial command to projector as one BYTE (keyspan USA-19QW)

    Feb 21 2010 | 5:51 pm
    I know this isn't the most popular thing to do these days, but I am attempting to control a device through serial commands. I've done it before, but this time Im a little stumped.
    I need to send the following (according to panasonic manual and tech support there)
    STX as one byte - but of course when I use atoi / spell in conjunction with the serial object, it sends 3 bytes.
    What am i missing here to be able to send a string as a single byte?
    I would really appreciate some help on this one...
    Im using a mac mini, OS 10.5, max5 + keyspan USA-19QW USB->serial adapter
    thanks in advance matthew

    • Feb 21 2010 | 7:03 pm
      STX must be a nemonic for some byte, no? An ASCII character is 7 or 8 bits, depending on your definition, so "STX" could never be sent as one byte as ASCII.
      Is there a link to the manual for the projector?
    • Feb 22 2010 | 4:13 pm
      here's a link for the serial protocol:
      Sadly, panasonic tech support has told me they won't help me, as they do not support usb-> serial converters. strange, but I think I may call them and pretend to be someone else. though if you have a clue, it would be a help.
      Ive tried with a nullmodem cable, a pass through cable, and just nada, nothing doing, so I am guessing it has to do with this STX 'command' ETX string.
      thanks, matthew
    • Feb 22 2010 | 5:04 pm
      I've seen this before where the commands were sent in hex STX = 02 ETX = 03
    • Feb 22 2010 | 6:58 pm
      Turns out STX and ETX are ASCII control chars: STX == 02 ETX == 03
    • Feb 22 2010 | 10:03 pm
      Wow, this is a great resource - I was a little lost here. One last question and I can link this all together, how do i send hex numbers out the serial object?
      thanks for your help guys...
      best matthew
    • Feb 23 2010 | 4:44 am
      As an update to the above - I've tried everything I can figure out, but of course sending anything through the serial gets converted to an integer there. So sending a '2' actually results in '50' - spell, atoi and so on don't cut the mustard.
      so how to send hex out the serial port then?
    • Feb 23 2010 | 11:10 am
      I've done a projector remote to switch on and off the projector with serial commands. It uses an arduino only. You can find details (in french) at and code at
      Hope it helps.