Labview though windows 98 and ISA port: Speed trouble

[MVidal]

Dear Sirs:

We are developing an application that should send and receive data (PCM) trough the ISA port (Own made card).
What we have found is that the max. speed we can have to send and receive data (we are under windows 98) is about 1.6 Mhz. And we require 4 MHZ.

Can someone give us a light about it?

Those are the first routes we are considering to explore:
- There should be something in LabView to address the problem (but what?).
- If we could compile it (under DOS) we can achieve the desired speed.
- We can put an external array of memory with the data to manipulate (consider the development resources).

Thank you for any help on this matter.

Best regards,

Javier Mauricio

[mikeporter]

You are going to need to go through your code very carefully making sure that you aren't doing any unnecessary processing and the necessary processing is being done in the most efficient manner possible. Pay particular attention to arrays because inefficiencies there multiply their effect. Also use the execution profiling option to help you identify where the code is spending the time.

The first place to start is with initialization and deinitialization routines. Make sure that you aren't reptatively opening and closing ports or channels. Next, verify all your array handling is managing the data in the most efficient way. In time critical applications like this be extra careful of operations that cause LV to have to manage memory on the fly. In general you w
ant to preallocate memory and update values rather than accumulating data. Finally, be on the lookout for operations that you perform but aren't needed. For example, say the output of a subvi is only used in one frame of a case structure. Make sure the subvi is inside the case where its used so you aren't executing it for cases that won't use its output.

Are you seeing better performance with a built application? Though I have never noticed the effect myself, I have heard that built applications can run slightly faster because they don't include debugging code.

One non-LV related thing to look into is the operating system itself and the overhead it imposes...

Hope this helps,

Mike...

[MVidal]

Mike:
Thank you so much for your answer.
I think it's more in that direction: communication between LabView and the ISA trough the Win98, instead of processing time. I've been told that Win9x limits the speed of the ISA... I have to confirm it...
Thank you again.
Javier Mauricio

[mikeporter]

You might want to try Win2000, I don't know how it would effect this problem but from everything I've heard it's a much more stable operating system. I've been using it for over a year and am very pleased with it--well as pleased as you can be with any Microsoft OS...

Mike

Mike...