Perl program to read PPM from telaire CO2 monitor.

I have been playing around with a re-branded telaire 8001 co2 monitor and have managed to figure out enough of the communications to read the PPM from the serial port.

I think I paid $35 for this thing on ebay a few years back..

If you need a serial cable to interface it with your computer check out this link.. Making a serial cable for a Telaire CO2 sensor .: Cannaversity

Here are a bunch of runs of the program reading the values from the monitor. Tword the end you can see where I exhaled into the sensor.

Code:

delphi tmp # ./ppm.pl
406
delphi tmp # ./ppm.pl
409
delphi tmp # ./ppm.pl
408
delphi tmp # ./ppm.pl
416
delphi tmp # ./ppm.pl
476
delphi tmp # ./ppm.pl
685
delphi tmp # ./ppm.pl
685
delphi tmp # ./ppm.pl
1137
delphi tmp # ./ppm.pl
1773
delphi tmp # ./ppm.pl
2120

Here's the program. It's incredibly crude, but it works.
I'm running this under linux, through a Prolific brand USB to Serial adapter. If you are using a native com port, or on windows you will have to edit the definition of $PORT to match your serial port. Note this program requires the Device::Serial module to function..

Code:

#!/usr/bin/perl -w
#
#

use Device::SerialPort ;

$PORT      = "/dev/ttyUSB1";          # port to watch
$REQUEST   = pack'H*','FFFFFE0202037605';

#
# Serial Settings
#

$ob = Device::SerialPort->new ($PORT) || die "Can't Open $PORT: $!";
$ob->baudrate(9600)   || die "failed setting baudrate";
$ob->parity("none")    || die "failed setting parity";
$ob->databits(8)       || die "failed setting databits";
$ob->handshake("none") || die "failed setting handshake";
$ob->stopbits(1)       || die "failed setting stopbits";
$ob->handshake("none") || die "failed setting handshake";

$ob->write_settings    || die "no settings";

$ob->write($REQUEST);

sleep 2;

$result= unpack('H*', $ob->input);
$hexr = substr( $result, 10, 2) . substr( $result, 8, 2);

print hex $hexr , "\n";


$ob->close;

undef $ob;

 

Thanks. It took most of a evening dorking with a serial port analyzer. At least nothing was encrypted.