DAQMx read Error -200279

[Water]

Hi,

I have this problem(error code -200279:Attempted to read samples that are no longer available) when I placed the DAQMx read vi into a stacked sequence which is inside a loop. What I intended to do is to move a stage and acquire a reading for n numbers of reading. Both of these actions are framed into a sequence stack and put within the loop. Is this correct way to do acquisition?

Some of the ways I have tried to overcome this:

1) Putting DAQMx start/stop within the sequence with the DAQMx read. It solve the problem but I have read that starting and stopping task within the loop will dramatically reduce the perfomance of the DAQ card

2) Increasing buffer. I have tried to increase the buffer to about 40 times the size of the sample count needed but the problem still persist. Do I also need to decrease the sampling interval?

Need your advice

THanks

[Robert_F]

Hi Water,

I would suggest using a Producer-Consumer Architecture to implement your application.  Here is a great resource on how to implement this architecture.  Now you can have one loop continuously acquiring data and the other loop can manipulate the data.  There are many continuous acquisition examples that will help you in the LabVIEW Example Finder. 

It seems that you are filling up the buffer (FIFO) on your DAQ because you are trying to manipulate the data.  The error that you are getting is identifying that you are taking too long to manipulate the data and not reading the data from the buffer fast enough.