On the PXI-5422 how do you change the buffer to allow for smaller frequencies?

[Jamieo7]

I am running the niFgen_Function_Generator_Example VI in LabVIEW and I do not want to use such high frequencies. The highest I will possibly need is only 2MHz. If I try to lower the frequency on the dial, I get an error message that says:

Frequency is too small. To generate at lower frequencies, increase your maximum buffer size.

How do I increase my maximum buffer size?

Thank you.

[Drew Creel]

To increase your maximum buffer size for standard function mode, set the "Maximum Buffer Size" attribute:  in the NI-FGEN LabVIEW property node, "Standard Function Output->Maximum Buffer Size" or in C/C++:  NIFGEN_ATTR_FUNC_MAX_BUFFER_SIZE.

You can either set it to something really large (like the memory size of your board) or calculate what you need with the following formula:

max buffer size = max sample rate / minimum frequency

The max sample rate on the 5422 is 200 million samples per second, so if the smallest frequency you want to generate is 10 hertz, set the max buffer size to 20 million samples. 

Drew Creel

NI Software Engineer

Signal Generators