Passing a large 3D-array to a sub vi and back causes huge loss of performance

[JohannesK]

I am passing a large 3D-Array of type I16 to a sub-vi node of same type, and back to the main VI. For test purposes I have removed all processing in between. Still, the sub-vi call requires many ms to s, depending on array size. I was under the impression that variables are passed to sub-VIs by reference. Is this incorrect? can it be fixed?
Johannes

[wiebe@CARYA]

Hi,

Is the subVI's front panel open or closed when you try this?

If it's open, the (graphical) updating of the input control and output
indicator might cause the overhead.

Regards,

Wiebe.


"JohannesK" wrote in message
news:5065000000080000003A670000-1031838699000@exchange.ni.com...
> I am passing a large 3D-Array of type I16 to a sub-vi node of same
> type, and back to the main VI. For test purposes I have removed all
> processing in between. Still, the sub-vi call requires many ms to s,
> depending on array size. I was under the impression that variables are
> passed to sub-VIs by reference. Is this incorrect? can it be fixed?
> Johannes

[Ben]

Hi Johannes,

(There may be exceptions but) No, variables are not passed and returned by reference.

"A fix" may be possible by restructuring your app such that the large 3d array never gets moved around. This can be done by using what I call an action engine. It uses a variation of the LV2 global to store the large array ONE TIME in a shift register. After that, all other operations are performed "in-place".

This technique has allowed me to process very large data sets "on-the-fly".

Ben