GPS data logging

[BK9576]

Hi All,

   I have a bit of a problem that you might be able to help me with. I'm working on recording data from a GPS (THALES) along with 5-other sources of data and logging it to a file. I've tried a couple different methods but can't get it to synch up past 5-Hz and I need at least 10-Hz. The GPS is good to 30-Hz as well as the other hardwqare but trying to capture, then record and parse out the GPS data and collect it with the rest of the data is a mess and SLOW! I'm using RS-232 to connect to the GPS and that might be on e of the issues. no?

Right now, I ping the GPS, collect the data, bunch it with the rest of the data then send it to a file. BUt If i run it too fast, i get bits and pieces of the data from the gps.

Any suggestions would be greatly appreciated! Oh, I am using labview for all the data aquisition stuff.

Thanks,

BK

[Brian_Beal]

I've done something similar with a Thales DG16.  If I recall, the best I got was about 8Hz.  It sounds like you are not waiting, or looking, for the GPS data to finish.  Could you post your VI?  Using serial isn't the problem.  I have obtained data from basic serial instruments at over 130Hz before.

[BK9576]

Hi Brian,

   Thanks for the quick reply! Actually, I think waiting for/ looking for the GPS data to finsih might be the best bet at this point.

The format is something like $PASHR, ,,,,,, (18 points of data).  Do you have a hint on how to accomplish this task? I dont think i can post the VI (unfortunately) 😞

If I can look for the stream and record the otehr data at the same time that might do the trick! I know the GPS will dump the data ata 10Hz but syncing it up with the other encoders, etc is tricky. it must be precise! (or pretty darn close).

Any other suggestions hints? Is there a VI that I can use to watch for the data? How should I structure it? ie, block diagram wise?

Thanks Again,

BK

[Brian_Beal]

I will post a VI later tonight.

[BK9576]

Sounds great, thanks!

[Brian_Beal]

Here it is.  You may have to modify it, but this will give you an idea.  Let me know if you have any questions.  Thales Get Bas.vi is the top level VI.  This is a few years old, and I may do something differently these days, but this worked perfectly in my application.

[Brian_Beal]

I don't know why I didn't do it, but it appears that the returned message will end with a CR/LF, so you should be able to enable the termination character and use that for the VISA Read.

[BK9576]

Hi Brian,

   Thanks for the posts! Yup, that did it! for some reason i was waiting for the number of bytes from the gps. The termination character did the trick! 

Thanks again for your help!

-BK