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

mbiederman's icon

Hello,

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

Chris Muir's icon

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?

mbiederman's icon

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

Scott Fitzgerald's icon

I've seen this before where the commands were sent in hex
STX = 02
ETX = 03

~s

Chris Muir's icon

Turns out STX and ETX are ASCII control chars:
http://www.december.com/html/spec/ascii.html
STX == 02
ETX == 03

mbiederman's icon

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

mbiederman's icon

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?

taprik's icon

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
http://machines.zombideo.net/?cat=11
and code at
http://zombideo.net/appli/arduino_code_proj_command.zip

Hope it helps.