Shared variable RT FIFO (multi element) - Read all at once

[mgulin]

Hi all!

I'm trying to collect data from analog inputs on my cRIO with a 1 sec time step. For that purpose I use a Timed loop and a shared variable with RT FIFO enabled (multiple array of doubles). Parallel to the timed loop, I also use a while loop that is significantly slower (lets say 10 sec period) that should read all arrays stored in FIFO and write them down in a .txt file (everything is executed locally on RT target). Is there a way to empty the RT FIFO shared variable at once, and if no how can I get a number of arrays that are currently stored in a shared variable?

What is the difference between RT FIFO created by a shared variable and the one created using Real-Time/RT FIFO palette? I prefer using shared variable instead of Real-Time/RT FIFO since it also allows timestamping.

Best regards,

Marko.

[BauerPower · Accepted solution]

Marko,

We recommend that the non-deterministic loop run faster than your deterministic loop and pull off samples when they become available. If you don't want to do this, you can simply put your RT FIFO read in a For Loop set to execute 10 iterations and then place that in your while loop. For more information on the differences between the RT FIFO and Shared Variables with RT FIFO enabled, please see pages 32-35 of the CompactRIO Developers Guide linked below.

http://www.ni.com/pdf/products/us/fullcriodevguide.pdf

Hope this helps!