Scan From String Problem

[stirlsilver]

Hi everyone,
I am very new to the LabVIEW scene and have been set with the task as a part of my thesis to create a system that displays and records a bunch of data from sensors fitted in an aircraft. The data is transmitted serially at 500Hz and is in the form <header 3bytes (AA55AA)><Identfier 1byte><data 10 x 2bytes (10 channels)><end 1byte (FF)><checksum 2bytes>.

I have managed to capture the data and successfuly parse out each of the 10 channels. But i'm experiencing a problem with scanning from the incoming string. Initially when I run the program it works fine with all the data being placed in the appropriate text boxes and updating. However channel 1 (only testing one channel input) after about 2mins of operation starts to become selective about the second byte of data that is displayed. i.e normal operation would be channel 1 displaying say A102, A109, A104, A10A in hex. As the operation continues it will stop displaying some values of the second byte i.e. if the same string were to come in on channel 1 again it will only display A102, A1  , A104, A10A. This will continue to progressively get worse as it continues to run. say A102, A1  , A104, A1  .

I have included my vi, there may be some error that I haven't picked up on but as far as I know I can't see any reason for this bizzare error to result. Any help would be greatly appreciated.

Stirling

[stirlsilver]

I forgot to add that this is running on LabView 8.2.1 on Windows 2000. I have not installed any service packs onto the operating system as of yet (if that has been known to cause problems). Thanks again
Stirling

[Tushar_Jambhekar]

I think everything should work fine.

i have done a small change using in the code just try it out.

if problem persist then it will be better if you record the data from serial port (say for 5-10 mins) in a text file and then post that file on forum. may be we can help you out in better way

Message Edited by Tushar Jambhekar on 04-05-2007 04:25 AM

[stirlsilver]

Thanks for your help Tushar,
However I have been able to duplicate the problem by using a string input in place of the serial aquisition, it seems it refuses to display 0A 0C and 0D. I have made some further modifications to the code to continue progressing so please ignore the mess in the block diagram. I have enclosed a picture of these hex characters dissapearing on me.
Thanks again!
Stirling

Message Edited by stirlsilver on 04-08-2007 12:11 AM

[stirlsilver]

[Tushar_Jambhekar]

try to use this

may work...

and let me know the feedback

[altenbach]

Maybe we should keep everything in one place to avoid duplicate answers and efforts:

http://forums.ni.com/ni/board/message?board.id=170&message.id=240521#M240521