Interleave​d data saving and the TDMS Viewer VI.

Question

Hello,
I'm using LabVIEW 2009 Service Pack 1 ( ver 9.0.1 32-bit ).
I was trying to take a piece of data and save it in interleaved mode.
The save operation seems to be completed correctly, but when the TDMS Viewer VI is launched it crashes, and I'm unable to browse the data.
I'm attaching the example I used.
What I want to know is:
1) am I using the write properly? What I'm trying to acomplish is to push down an array if I16 to a TDMS write block, recieve 30 channels of data this way.
2) I managed to use this VI and it crashes, on two PC's, one is a win7 32bit, the second one was an XP. But let me know if this runs properly for you.
Maciej
Attachments:
InterleavedDataErr.zip ‏16 KB

Answer 1

I have a buffer that can accumulate up to 65536 I16 values.
In that buffer I get for example 6x 10000 values.
Every "chunk" of the 10000 values is my interleaved data. One point is one channel.
My data is shaped like in the opening post:
http://forums.ni.com/t5/LabVIEW/TDMS-Streaming-in-​interleaved-mode/m-p/1189201#M513943
Since I'm running a windows machine, sometimes I'll get 5x 10000 values, sometimes it will be 3x , sometimes 6x during one buffer swipe.
The data rate and the channel length is variable.
But let's talk about one case:
10k channels and 10 kHz rate of I16 vals.
That gives me roughly 200 MB/s of data that I need to get out of the buffer.
What I want to do on my PC is take that data, and save it interleaved to a TDMS file, while being able to safely stay above the 200 MB/s.
I would be intersted in aiming for 300 MB/s so that if we push our card further down the line, I'm not stuck with the streaming bandwitch.
I have noticed that unfortunately if you use an ammount of channles that is 10000 the writing performance drops dramatically.
What I figured out is that I'm not conducting 1 write on 10000 channels on a small ammount of data. But rather than that a large accumulated amount of data (like 8000 x 10000 of I16)
And I split the save of 10000 channels into 10x 1000 channels save.
First channs from 0-999 , than 1000-1999 etc.
All is done in interleaved mode.
This is Very Very fast indeed. I got rates of 360 MB/s. That's smoking fast!
Now the trick is... to handle the appropriate data shaping in the RAM, from my buffer, to the large shaped RAM chunk, that will be cut in to pieces for Streaming. LV is designed for data flow and copies data a lot, hence I get easlity in the out of memory problem, I'm going to have to use some ticks like storing the data structure via a VI Server call, or perhaps queues don't know yet. But I'm going to do some reading on that and it seems that this should be achieavable.
Thank you both for your input,
I will post if I get stuck.
Maciej