RT FIFO Bug?

[eesen]

Hello,
In my application, in first loop a write 2D sample to an RT FIFO (see RT FIFO write loop),
and in the second loop ,i read data from RT FIFO (See RT FIFO read loop). Please do not questionare
why i transfer data, i just send simplfied version of my application and for some reason i should do this.
Focus on the RT FIFO
Anyway, i put a break point outside the RTFIFO at debugging and i get result in picture(see RT FIFO).
As seen in the picture, after the point 15, data has changes.Data read from RT FIFO is different from written.
(When i create RT FIFO for 1D array, there is no problem, see RT FIFO_rev2, perhaps RT FIFO doesn't support 2D array?)

Message Edited by eesen on 05-17-2007 08:33 AM

[Nadim R]

Hi,


The error you are seeing is expected behavior- RT FIFOs unfortunately, do not support 2D arrays at this time.  Have a look at this knowledgebase for more information (see bottom of KB).  Note that you must convert your 2D array into 1D to get it to work with RT FIFOs.  Another solution for you is to use RT FIFOs with Shared Variables.

I hope this helps,

Regards,

Nadim
Applications Engineering
National Instruments

[eesen]

Thanks for explanation.

But if RT FIFO doesn't support 2d array, whay type input except 2d array time, or in its description, why this limitation isn't written? I lost time to find where is the problem, anyway.

[NIJanell]

Hello eesen,

This limitation is actually documented - like in the KB linked in Nadim's response, among other places.  I agree that it is a little difficult to find, so I will add some additional documentation on this issue.

Happy programming!

Janell R | applications engineer

[FabiolaDelaCueva]

Just a suggestion. Would it be possible to include this and the fact that they do not support string types as denoted here:

http://digital.ni.com/public.nsf/allkb/4C0DD3F01279A34286256F86007F031A

in the LabVIEW help?

That is the first place I thought of looking for an answer.  There is a note at the bottom regarding variants, but nothing regarding 2D or strings. Also, this note would probably be better right next to the type.

Thanks,

Fabiola De la Cueva

Certified LabVIEW Architect and Instructor 

[Claire_Reid]

Hi Fabiola,

Thank you for this suggestion. It is definitely a valid one, and I will speak with R&D and see what can be done. I will post back with what I find.