serial command to projector as one BYTE (keyspan USA-19QW)
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
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?
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.
I’ve seen this before where the commands were sent in hex
STX = 02
ETX = 03
Turns out STX and ETX are ASCII control chars:
STX == 02
ETX == 03
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…
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?
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.