Cycling 74 » Topic: serial command to projector as one BYTE (keyspan USA-19QW)

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

mbiederman — Sun, 21 Feb 2010 17:51:54 +0000

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

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

Chris Muir — Sun, 21 Feb 2010 19:03:59 +0000

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?

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

mbiederman — Mon, 22 Feb 2010 16:13:23 +0000

here’s a link for the serial protocol:

ftp://ftp.panasonic.com/pub/Panasonic/Drivers/PBTS/brochures/S_PT-AX200U.pdf

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

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

Scott Fitzgerald — Mon, 22 Feb 2010 17:04:14 +0000

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

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

Chris Muir — Mon, 22 Feb 2010 18:58:35 +0000

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

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

mbiederman — Mon, 22 Feb 2010 22:03:09 +0000

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

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

mbiederman — Tue, 23 Feb 2010 04:44:49 +0000

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?

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

taprik — Tue, 23 Feb 2010 11:10:16 +0000

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.