HSDIO digital data acquisition problem – losing data

[salomiva]

Hi!

I have to make a simple project that acquires bits from a single digital line (2Mbps), searching for a certain 88bit pattern (BARKER) and after finding it stores 8000 bits from the channel in a txt file of a certain format. For the acquisition I use PXI 6552 (with 8Mbits per channel on board memory). I have developed my project based on Dynamic Acquisition examples and it seemed that it worked fine until I discovered that I am actually losing some data and that I detect only every 10^th to 20^th barker sequence (I am monitoring data via oscilloscope as well so I am certain that I do not detect every barker sequence). I also noticed a sporadic warning

Warning 1803 occurred at DTbl Digital Subset.vi->DTbl Search for Digital Pattern.vi->LineSequenceTest_v24.vi

Possible reason(s):

LabVIEW:  Waveform x-axis value requested is out of range.

but I do not understand what could be the problem and could that problem be the cause of losing data.

Thank you!

[bocasy]

Dear salomiva,

I suggest to use a Producer-Consumer architecture https://decibel.ni.com/content/docs/DOC-2431 ,

because you will read continuous data in producer loop and handle the writing data into consumer loop, so in this way you will buffer all data.

It will require you more time to implement this but this way you will be sure of no data lost.

Best regards,

Andrei B.

[salomiva]

Thanx a lot! It seems that the problem really is the “high” 2Mbps speed because when I reduced speed to 128kbps it works fine. So the solution you showed me should help me. I will inform you how that works for me!