Data logging application Labview FPGA RT only recording whole numbers

[jackson.jaro]

Hello, 

I am trying to record data using labview FPGA. I am using a NI cRIo 9039 with a NI9215 i/o port to read data. I followed the tutorial called "Taking Your First Measurement in LabVIEW FPGA" which uses a FIFO to read data and then write it to the disk.Link here: http://www.ni.com/tutorial/54219/en/

after completing the tutorial, I tried the program out on a 1 khz sine wave with 6v peak-to-peak amplitude and it only records whole numbers, with every other number in between recorded as zero. 

I checked that I am not spuriously using "int" types, so I'm not sure where this error is occurring.

Attached is the "measurements from tutorial.vi" which sets up the FIFO and fpga and the "measurements.vi" which interfaces with labview on the computer. These are inside "FPGAtestproj."

Thank you in advance for the help!

[Brian.D]

Hi jackson.jaro,

I believe you are running into an issue with using fixed-point data and transferring it to your target via a DMA FIFO. I recommend taking a look at the following document for how to configure this (both on the FPGA and the RT): https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000P8wdSAC.