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Adjusting sampling frequency with Ni USB 8451

Hello all,

 

I have successfully created a program to collect data from multiple SHT 85 (temp/humidity) sensors using a NI USB 8451 DAQ (attached here).

Since all of my SHT85 sensors have the same Hex address, I am using a multiplexer to cycle through the different SHT85 sensors.

 

Sub VIs:

1.  to get Temp./Humidity data from SHT 85 sensor.

2.  to select multiplexer (I plan to add more multiplexers in the future to accommodate more sensors).

 

Is it possible to select/create a sampling frequency? Currently the sampling frequency is too high and I want to reduce it to say 1 Hz (1 sample/sec)

 

Currently I am utilizing a ms wait timer to delay the data recording/collection as per my required sampling frequency. The problem is, sometimes (when I set the sampling freq. = 1 Hz) the data gets collected at say 1s or 2s time intervals. Is there a better way to set the sampling frequency?

 

I have attached a LabVIEW code to collect data from 2 SHT85 sensor attached to 1 multiplexer.

 

Thanks,

Punnag

 

 

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Try using the 'Wait Until Next ms Multiple' instead of 'Wait ms' to make the logging interval better

santo_13_1-1617316350429.png

 

Better to Close the session after the whole logging is complete

santo_13_2-1617316422438.png

 

 

 

-Santhosh
Semiconductor Validation & Production Test
Soliton Technologies
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Thanks for your suggestions. However, this still does not solve my issue of selecting (user control) a specified sampling rate such as 0.5 Hz or 1Hz, etc.

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