PXI: NI 5600, data lost or stored if the loop time of processing is slow than the acquisition.

Question

I want to know what occurs exactly at the time of L acquisition and the processing data acquired with Ni 5600.  When J write my programme of processing of data in Labview, if the loop time of processing of data is slow than the acquisition, I want to know if PXI put the data in a buffer or then the data are lost. 
J wait your answer impatiently. You can tell me the documentation were can i read to see the answer.
Anybody can help me.

Answer 1

hi abidi,
First, let me tell you how buffered acquisiton works.
If you are using Daq mx for continous acquisition, Labview will autoselect the size of buffer depending on the sampling rate specified.
In sample clock.vi, select sample mode as "continous samples".
Now, Labview will determine the loop speed for reading data that is written into the AI buffer and hence run  necssary number of AI read loops to retrieve data from the buffer every second.
this loop speed can also be set by specifying "number of samples per channel" in AI read.vi.
If you leave this value at default ( -1) labview will function as explained above
This can also be set by user ,for example, if your sampling rate is 1000 saples per sec and number of samples per channel is 200, the AI Read functions is performed 5 times in a second. 
read this link to get to know about cyclic buffers and continous acquisition.
http://zone.ni.com/devzone/conceptd.nsf/webmain/F2DDCBAD754C687C86256802007B8514
You tell that you are performing some processing on acquired data.
Now, your prgram has to allocate adequate process time for acquiring,retriving data from buffer and then processing it.
the time allocated for processing data depends on the kind of mathematical conversions involved. Nevertheless it is an overhead on the acquisition loop.
this may result in overflow of buffer and data being overwrittien in buffer which results in data loss. An eror message might also pop up to warn that this has happened.
so if your application permits, here's what you can do to avoid this problem
First acquire data and save it on system in ascii or binary fromat.
later retrieve this data file and perform processing /analysis on it.
if you have any further doubts, plz tell.
regards,
Devchander M