A simple analog input task not working on PXI 6259

[Vicku]

Hi,

I am a new user of NI software and hardware (PXI). I am going through the tutorial  "Demo - Programming IO in LabVIEW Real-Time"  in "NI Real-Time Ekit" downloadable from http://www.ni.com/realtime/     .

The simply followed along with the tutorial and created the exact same VI as was made in the PXI section of that tutorial for reading an analog input channel. But my VI gives error 200428. Based on the description of this error I checked several times that I am connecting the correct task to the DAQmx Start VI, it seems right to me but it is not working. I am attaching the tutorial as well as my VI with this message. Any kind of help would be highly appreciated.

Thanks and Regards,
Viku.

[Vicku]

I might have located the source of the problem. In the labview project window I have a DAQmx task that reads analog voltage from a single ai channel. When I double click on it in the project window the DAQ assistant opens. There when click run to test this task. I get error 209802 DAQmx wait for Next Sample Clock detected one or more missed sample clocks since the last call to Wait for Next Sample Clock.

I am not able to figure out how to fix this problem. This is a very small application where I am only reading an analog input from a single channel using a PXI6259 card with PXI controller 8196 and I do not expect it be slow.

Any kind of help would be appreciated.

Vivek.

[Jesse_O]

Hello Vivek,

The last error you mentioned is caused because your computer is not able to read one sample at a time fast enough.  For example if your computer is capable of running that acquisition loop 500 times a second, but you tell the hardware to acquire at 1000 Hz you will get this error.  You need to make sure your loop runs faster than your acquisition.  To make sure the example runs you can decrease your acquisition rate in the DAQ Assistant to something much smaller.

Alternatively, you can use one sample on demand or buffer your input with N Samples or Continuous acquisition.  You can find more information on these timing types inside of the DAQmx help manual (Start >> Programs >> National Instruments >> NI-DAQ >> NI-DAQmx Help).  If you search for "Sample Timing Types" it should be the first item found.

I hope this helps.  If there is anything else I can do please let me know.

Regards,

Jesse Ormston
Applications Engineering
National Instruments