PDA hang up at high serial transmit rate

[arvin_labrat]

I'm tring to make a PDA App that will communicate with a test box.  I can send and receive information but when i try to stream data to the PDA at high rates 21 bytes @ 20 ms intervals the app hangs up.  I'm not sure how to trouble shoot the app on the PDA so I don't know what part of the code is causing the problem.

I'm using an IPAQ 5550 with 128 MB of memory but only half is allocated for running apps.

My software is Labview 7.1.1 with Labview PDA Modual 7.1

If made some example VI's, one to simulate my test box and one to simulate my PDA app.

If any one can give me some suggestions on how I can accomplish my task I'd appreciate it.

If tried running the PDA Recieve from my laptop and it worked perfectly.

Thanks in advance

Eric

[Chris_Cilino]

Eric,

As of LabVIEW 8.0, you can build a debuggable executable and use it to trouble shoot your code. You are able to view the block diagram running on your PDA from your host PC while the VI is actually running on your PDA.

Since this isn't available in 7.1 I suggest that you use either the counter in looping structures connected to an indicator to find out which iteration of the loop the "hanging" occurs on or you can use boolean indicators placed throughout the program. You can also write to a log file to keep track of which part of your program executes last.

These are just some ideas. If anyone has others, please let us know. Thanks!

Chris C

[arvin_labrat]

Thanks Chris for your reply

I think I have it narrowed down to a null character transmit.  When ever I try to transmit a null (0x00) to the PDA at >= 50hz my app locks up.  All other characters seem to transmit ok.

I'm using the default comm port on the PDA.  The one it uses to sync to a computer.  I would like to verify that I could work around this by using a PCMCIA Serial I/O Card.  If someone with a PDA and a Serial Card could run my attached examples and let me know if any problems occur. If no problems occur I can could move on with my project development. 

The setting on the PC are Baud 38400, Period (ms) = 20, Start Character = 255, End Character = 0.

Thanks in advance

Eric

[arvin_labrat]

Chris

Do you know of any issues with Bytes At Serial Port.vi or Serial Port Read.vi when reading a null character (0x00) on a PDA running Pocket PC 2003?

My version of Labview PDA Modual is 7.1.

Thanks

Eric

[Chris_Cilino]

Hmm... well I haven't heard of any problems with these two vis. Are you noticing the problem only when you transmit the null character at higher rates or any time you transmit the null character?

Chris C

[arvin_labrat]

Hey Chris

The exe on the PDA only hangs when I transmit the null character at update rates of 50 hz or more.  The port settings I'm using are 38400,8,N,1.  Each line of data contains 21 bytes.

It has to be something I'm duing in my code because I found an example exe (http://forums.ni.com/ni/board/message?board.id=170&message.id=71041) that works fine with the null character and the setting listed above.  It just very difficult to troubleshoot my problem.

Any suggestions would be appreciated.

Thanks for your help

Eric

[arvin_labrat]

Chris

I was able to get my app to work and my problem was not the serial compatibility VI's.  The problem is the string display being set in HEX mode.  I had the display set in Hex mode becuase I am transmitting a binary data and I can see all the data coming across, but for reasons unknown the whole app would hang when I sent a null character (0x00) at a high rate. 

Have you heard of anything like that on the display for the PDA?  I'm wondering if it is a bug of some kind.

Thanks for your replys

Eric