reduce sampling rate for strain data with NI9237 in DAQExpress

[DD_Flora]

Dear all, 

I am a new user for DAQExpress and NI9237.  The minimum sampling rate is 1.6KHz, However, I really need to get data with a lower rate.  Can anyone tell me how to either change the sampling rate or record or write the recorded data with lower rate such as 10HZ? 

Thank you very much.  Appreciate!

[Salazar.Slytherin]

Hello!

The 9237 has a Delta Sigma ADC that has a limit of 1.6 kS/s sampling rate. However, if you use an external master timebase, you can get as low as 391 S/s. 

[YWTSC]

Hi Salazar,

I met the same issue with reduce of NI-9237 sampling rate. Could you please show me how to apply external master timebase in DAQexpress to reduce sampling rate to 391Hz?

Thanks,

YW

[NTEC]

Did you get the answer of exactly how to reduce the sampling rate?? NI newbie!

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@YWTSC wrote:

Hi Salazar,

I met the same issue with reduce of NI-9237 sampling rate. Could you please show me how to apply external master timebase in DAQexpress to reduce sampling rate to 391Hz?

Thanks,

YW

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[YWTSC]

Nop, I still did not get how to reduce the sampling rate lower than 1612.9/s by "external master database".

Can anyone help?

Thanks in advance!

YW

[garrett.w]

Hello YWTSC,

I linked an article below that goes over master timebases and how to implement them in your code. 

As far as reducing your sampling speed for your code, you might be able to create a for loop inside a while loop that either averages the certain number of values or just exports 1 value however often you want. 

Synchronizing Analog Input C Series Modules with NI-DAQmx in LabVIEW 

http://www.ni.com/tutorial/5376/en/

Hope this helps. 

Garrett W.

[YWTSC]

Hi Garrett,

Thank you very much for your help!

I understand the article you posted the link, however, I do not know how to make it work in DAQExpress, which is a simple version of DAQmx. 

My task is to export the measurement data of pressure transducer (from NI 9205) and strain gauge (from NI 9237) at same sampling rate 5/s, both are at same chassis cDAQ 9174. Since NI 9237 has min sampling rate 1613/s, I need to reduce it to 5/s and sync it with pressure data together. If you know how to realize it in DAQExpress, please let me know. 

Best regards,

Yongkui 

[tmoritz]

Considering you posted this in 2017, you probably have already resolved this question.  My answer is for anybody else, like me, looking for the same answer. 

The sample rate can be adjusted in the Task window.  Once you have defined your channel, click on the Task tab, expand the Timing section if it is not already expanded by clicking on the triangle to the left of Timing.  In this section you can alter the Desired Sample Rate.  I have attached an annotated screen shot.

[WisaOregon]

Thank you for posting this picture...The software is not very intuitive but your screen shot explains it perfectly. Thanks again