Long data acquisition with VMEBus ;trigger missed

[jchomel]

Triing to acquire very long data sets (e.g. 100000 on 10 canals), I noticed computing speed decrease as the data set is large. This should be due to realocation of the whole data array as some measure comes in.
The time that should be alowed to CPU can't overlay a certain limit, so that i can't afford IO opperation to reduce the data array size in memory. Isn't there a simple way to push values into a statically allocated array ?

Thank you in Advance, Julien.

[preston_johnson]

Julien,

thank you for your question. How is the data transferred from the VME bus to the LabVIEW application? NI has new streaming to disk examples that take data from a number of channels (upwards of 56) and stream these to disk at 100k samples per second per channel. We have various benchmarks depending on the time lenght of data capture (minutes, seconds, etc) and on data acquisition boards. Many of these benchmarks have been done with our new 6115 and 4472 boards which are high speed acquisition boards. Once the data is recorded in permanent storage, then your application is able to retrieve and process the data. If you need to process the data as it arrives, there are a couple of appnotes on performance for labview, especially in the area of arrays a
nd how LabVIEW manages space for arrays. You should find these on the developer zone, LabVIEW+Array in seach fields.

I hope this helps.

Preston Johnson
Business Development Manager
National Instruments
512 683 5444