Synchronize NI 9225 and NI 9227 in CDAq-9178

[JulianHartmann]

Hello,

i am quite new to this topic. So i try to synchronize a NI9225 and a NI9227 in the cDAQ-9178. The Code is written in LabVIEW 2016. I used this structure to synchronize my analog Inputs ... 

http://www.ni.com/tutorial/app/largeimage?lang=de&imageurl=%2Fcms%2Fimages%2Fdevzone%2Ftut%2FImage_8...

... the Problem is that the Sample Rate is 1613Hz, also when i try to choose a higher rate. 

How can i for example choose a sample Rate like 20kHz? Is that even possible?

When i run one module alone, i have no Problem to reach sample rates like 50 kHz.

Thanks for your answer.

Best regards 

Julian

[PatrikKaranNI]

Hi Julian,

The answer to your question is: No, you cannot choose rate 20kHz.

The reason is, that both of your cards have Delta-Sigma ADC and own timebase. NI C Series cards usually have either 12.8 MHz or 13.1 MHz timebase. Based on that you have only limited number of data rates, which you can use in with your DSA card.

Your NI 9225 and NI 9227 have 12.8 MHz timebase. In section "Understanding NI 922x Data Rates" of datasheet, you can find formula based on which you can calculate possible data rates.

OPERATING INSTRUCTIONS AND SPECIFICATIONS NI 9227

OPERATING INSTRUCTIONS AND SPECIFICATIONS NI 9225

To make it easier, you can refer to data rates of NI 9237 (same timebase) listed here:

Valid Sampling Rates for NI DSA Devices

Hope this helps.

Regards,

[JulianHartmann]

Hi Patrik,

this information helps a lot. Thank you for your help.

Regards,

Julian