reading NMEA data from COM port

Hi,

I am developing a GPS data logging application in C++, basically a
windows
service where i read GPS data from the device and write it to a text
file. I use CreateFile function passing the port number as an
argument. The GPS device outputs the data every second. I want to
identify this event i.e., i want to read from the port only when the
GPS outputs the data. Currently my program is not in sync with the
device causing my program to read only a part of the data i.e., if
the
device outputs 6 lines of data my program read only the first few
lines or the last few lines of the data. I want to synchronise my
program with the device. I want to read data only when it outputs the
data. Is there a way to do this. Is there an event which i can handle
when the device outputs the data?


Thanks
bharath

This doesn't sound like a GPS problem. Perhaps a C++ forum would be a
better place to ask this qustion.

--
Clarence A Dold - Hidden Valley Lake, CA, USA GPS: 38.8,-122.5

On Thu, 22 Nov 2007 04:15:46 -0800 (PST), bharath_r


You need an interrupt-driven serial receive routine. This routine
will be called each time the UART has received a character, and will
store the received character in a buffer. The main program can then
read the data from the buffer at its leisure.

--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

You will need to essentially generate that event yourself, i.e. parse and
package up the data yourself. But google around first, I found some Java
code some time ago that did that, theres probably some C/C++ examples also.

You might need multiple threads also to avoid losing data from the serial
port.

Depends on your language. More details, please.

I do it just find in Visual Basic. Never miss a character.

Mike

On Thu, 22 Nov 2007 04:15:46 -0800 (PST), in sci.geo.satellite-nav