DAQ sampling Rate

[AeroDesign]

My structure is pretty simple.It's similar to the continuous acquire and chart examples... I have the read vi in a while loop and the info is going to a chart, table and write file, while checking for a "greater than" condition. No trigger (sorry). The data is acquired until I press stop. I'm using LabView 7.0 and my lag time is about 10 seconds!!!

[JDesRosier]

Hello,

Are you writing the data to the file during each loop iteration? Oftentimes, users experience a severe performance loss when writing to file every time the loop iterates, because the computer has to read from the system RAM, find the correct write position on the HDD per instruction from the CPU, and physically write the data using the HDD.

Here is a link that you can read through to evaluate poor performance issues with LabVIEW.

I recommend that you write to a queue during each loop iteration and pull all information from the queue after the loop is complete. Then you can write the data to file. For more
information regarding programming with queue's, please reference the following link.

I hope this helps!

Best Regards,

Joe Des Rosier
National Instruments

[AeroDesign]

I changed the value for "scans to read at a time" in the read.vi from -1 (all) to a value less than my sample rate. In this case, my sample rate was 5/s, so I changed the value to 1. Therefore, as soon as 1 sample is read, I get data. Now, the program doesn't wait for "all" samples to be read, which can take a while when you're reading at a slow rate.

[juopa]

I have a similar problem..I want to get a measurement reading from my daq card 6036E pcmcia at the rate of 1 sample/1 second but I haven't managed to get it rigth. instead my labview program waits a period of time and when I press the stop-button i get error 200284..??