Error on calling niScope_fetchComplex function with simulated Ni PCI-5105 device

[amurthy]

On calling the niScope_fetchComplex function, I get the following error message:

"The requested fetch data type does not match the acquisition data type."

I was able to successfully execute the niScope_fetch function. I have attached the C-code I used to this post (Visual Studio 2012 project). I am using a simulated NI PCI-5105 device on NI-MAX.

Any information on why this error is generated and how to resolve the error would be helpful. Thank you for your help. 

[Nathan-P]

calling niScope_fetchComplex is not supported on the NI 5105.  This fetch type is for instruments like the NI-5142, which has Onboard Signal Processing, which can do DDC (direct digital downconversion).  This fetch method is for fetching the I & Q Data from the DDC, which the NI 5105 doesn't have.  

For fetching data from you NI 5105, use niScope_Fetch, or niScope_FetchBinary16.

-Nathan

[amurthy]

Hi Nathan,

Thank you for the quick reply. As you mentioned, I added a NI PCI-5142 simulated instrument in NI MAX, updated the logical name in the C code. However, the same error "The requested fetch data type does not match the acquisition data type " is returned. I found this to be case, even when I choose PXI-5142. Are there any additional parameters I need to set to enable fetching complex data?

Regards,

Adarsh

[Nathan-P]

You can check out the example "niScope EX OSP Baseband Decimation.vi" to see how the fetch complex is used.  For your particular error, you need to set the acqusition mode to "Complex", which is by default "Real".

This can be done using the niScope Property Node "Data Processing Mode", or since you are using the C API, you need to configure the Attribute "NISCOPE_ATTR_DDC_DATA_PROCESSING_MODE".

I hope this helps.

-Nathan

[amurthy]

Thank you for your quick response and useful pointers. I was able to successfully fetch complex data! -Adarsh