Reduce the high actual sample rate (1612.90 hz) on acquiring analog voltage via NI 9229

[asthapa]

Hi, 

I am trying to measure the pressure (in the form of analog voltage input ) using NI 9229 module on cDaq9178. The program works good, however, the actual sample rate acquired from the voltage signal is very high (1612.90 hz) than required. I needed data for several hours and the maxm number of rows in tdms file is exceeded. Additionally, the data is too large and caused problem in processing.
I need around 20 - 100 hz. I tried changing the the samples per channel, samples per loop, sample rate setting to 100. But the result was the same. Can anyone advise on it what could be the cause or the solution to it?

I am attaching the screenshot and the labview program.

Thanks in advance.

best, 

Ashok

[santo_13 · Accepted solution]

This behavior is by hardware design and documented in the NI-9229 Specs ,

Your options,

1. Use LabVIEW decimate array to discard samples, for instance, log 1 sample for ever 10 samples
   1. I believe the DAQmx logging property node has features to do this, I don't have DAQmx installed on my computer to show this.
      https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019NDtSAM&l=en-US
   2.  
2. Apply averaging, average every 10 samples into 1 sample