fpga loop timer & sequence structure

[Garvacious]

Is it really necessary to have the Loop Timer in LV FPGA inside a sequence structure or can it be sitting inside a while loop by itself as in standard LV vi's?  I have several loops in an FPGA app. that seem to work fine this way, but one that is exhibiting strange behavior that I can't explain.

[DD]

It isn't mandatory that you have the loop timer inside a sequence structure,
but doing so ensures that the loop timing will be as expected. If I
remember what I read correctly, if the timer is just in the while loop, the
second iteration will run immediately after the first.

"Garvacious" <x@no.email> wrote in message
news:1129833646124-279923@exchange.ni.com...
> Is it really necessary to have the Loop Timer in LV FPGA inside a sequence
> structure or can it be sitting inside a while loop by itself as in
> standard LV vi's?&nbsp; I have several loops in an FPGA app. that seem to
> work fine this way, but one that is exhibiting strange behavior that I
> can't explain.

[.avi file]

Greetings !

     Loop timers have to be in a sequence. Any other wait function does not need it. The loop timer reads and sets flags. Please refer to page 2-7 (22 of 62) in the user manual located in the following link.

http://www.ni.com/pdf/manuals/370690b.pdf

It elucidate usage of timed loops in sequence structures.
Thanks and hope this helps
Best regards
Avi Harjani

 

[Garvacious]

Actually, it turns out that the strange behavior I mentioned in one of my loops was just a triggering problem with the scope I was using to probe the outputs, not the VI.    The VI seems to work just fine. 

From what Avi said above I gather that not having the loop timer sequenced will cause unpredictable behavior in the first two iterations of the loop only (?)  If so I probably am not seeing that on a scope since the loops run so fast.

Message Edited by Garvacious on 10-21-2005 04:57 PM

[Garvacious]

Correction- I read the manual and it sounds like DD is right-  only the first loop iteration should be affected, as you cannot define whether the code executes before or after the timer flag is set; the compiler would determine this on its own.