Which processes or threads uses the Shared Variable Engine (SVE)?

[MS7]

Hi,

I have nearly no experiences regarding to programming a cRIO. There are some things I do not understand.

Hopefully someone can help me to understand the work of the Shared Variable Engine (SVE).

I know that the SVE just works if a Shared Variable is used in a process of a VI but why? So now my question is, which processes or threads uses the SVE?

best regards, MS7.

[HoussamK]

Hi,

Prior to LabVIEW 2012, NI Variable Engine is listed as National Instruments Variable Engine in Windows Services.

When a shared variable is deployed to a real-time target, there is no physical location where the shared variable or its library is stored on the target. The variable is a part of the shared variable engine installed on the controller and will stay resident there until un-deployed.

[MS7]

OK, I understand, thanks for the reply.

But ...

I have a WHILE-loop in my VI and when I decrase the delay for the loop I get more and more false values at the beginning of the test and data loss during the test.

I mean with a slow loop (e.g. 500ms) I get all values in a "synchronous" way. In a fast loop (e.g. 10ms or faster) the VI is not synchron and I loss some data.

That is why I ask whether the SVE needs also time to manage the Shared Variables or what is the reason for this behaviour?

best regards, MS7.

[HoussamK]

could you please post your VI or a screenshot, so that othe forum users could have a look on it?

[MS7]

Here my VI, I send the data from the cRIO to the computer.

It is just a counter but you see the differences between the delay times.

First picture show in fast loop I lose the first values. In this case the numbers 1 - 7. And additional I do not understand, from where are the values which resides in the lines 1 - 11?

Second picture show in slow loops I do not lose data but in this case, from where are the values resides in the lines 1 and 2?