Samples to read doesn't work well

[jyuan]

Hi, all,

I got a problem with my samples to read in SignalExpress. I set my rate as 1HZ, and samples to 10, no matter how long I recorded the data, I always got 10 values in my spreadsheet. For example, when I recorded my data for 5 seconds, I still got 10 there. Also, if I set my samples to read to 20, when running, I got an error message said "some or all of the samples requested have not been acquired, to wait for the samples to become available use a longer read timout or read later in your program..."

Does someone have any idea about how to solve these problems? I appreciate your time and help.

Thanks.

Yuan

[wfernand]

Hi jyuan,

If you set the samples to read to 10 and the rate to 1Hz you will be reading 10 samples every 10 seconds. When you set the samples to read to 20 while maintaining the sampling rate at 1HZ you get that error because the timeout occurred before any samples were received. Please follow the recommendations presented in the following document. 

Why Do I Get Error -200284 from my DAQmx Read VI?
http://digital.ni.com/public.nsf/allkb/FEF778AD990D5BD886256DD700770103

If you set the sampling rate to 2Hz and the samples to read to 20, then you will be reading 20 samples every 10 seconds. 

William Fernandez

Applications Engineering

National Instruments

[jyuan]

Thank you, William! I will study the document.