RT FIFO used on a non-RT environment?!

[BFD_LNS]

Hello everybody, I recently was assigned to porting/enhancing a project for Windows + cRIO/RT.

The Windows part of the code surprised me quite a bit when I noticed it was using RT FIFOs... but I was under the impression those would only work on an RT target, definitely not under Windows (I'm using a virtualized Windows 7 Enterprise environment + a cRIO 9066)

Tried to search this board and many other places but I can't seem to be able to find any documentation about this very specific case.

If I had to make an educated guess I would imagine that in a non-RT environment a call to an RT FIFO function simply gets re-routed to a standard Queue function... but it would be nice to have a confirmation on this (likely non standard/non supported?) use case.

Best regards

[Bob_Schor · Accepted solution]

I think the RT FIFO needs an RT-OS (that only makes sense, doesn't it?).  I must confess it never occurred to me to try using an RT FIFO on a Host system.  What makes a certain amount of sense to me is that NI is, indeed, configuring a Queue "behind the scenes", and probably setting it up as an "optimized" queue, pre-allocated, high priority, etc.  My advice would be to not use it (since you don't know what LabVIEW is doing here) and "roll your own" communication method (Channel Wires, anyone?).

Bob Schor

[BFD_LNS]

Yeah, that would seem a reasonable behaviour to me as well.

To be honest I didn't expect that function to show on the block diagram at all, if I'm not mistaken LabVIEW used to have a context-sensitive approach regarding functions made available on the various palettes but maybe something has changed (our team is new to LabVIEW 2017 so it could very well be the case, especially since we've basically moved from 2012)

I'll wait and see if there are additional replies, then I'll probably try to contact National Instruments directly.

Meanwhile I think I'll definitely follow your suggestion and avoid using RT FIFO on the host code!