How to set 80MHz sample clock rate in DAQmx with USB-6259

[Zhuoran]

Hello,

I am using USB-6259 BNC to do the analog input voltage measurement. I quickly tested with the Labview example: Voltage - Continuos Input.vi. I am confused with the selection of Sample Clock Source. When I select the Sample Clock Source as "OnBoardClock ", the DAQ works properly when the sample rate is below 100kHz. However, when the sample rate goes up to >100k, it reports error or does not work.
When I select the Sample Rate Source to "/Dev2/80MHzTimebase", no matter how much I input in the Sample Rate, like 1k,100k, 20M, 80M, the DAQ task reports error.

I check the spec of USB-6259 BNC, it supports the 80MHz timebase. Therefore, how could I use that timebase to do the fast sampling?

It coufused me many days. I would be very appreciated if anyone can help me!! Thanks in advance.

[santo_13 · Accepted solution]

For USB-6259 Analog inputs CANNOT be 80MHz, it can be 1.25MHz if only one channel or 1MHz (aggregate)

Since your DAQ is USB-based, I believe you can only use the onboard clock as a clock source. The 80MHz timebase is used for PLL/Counter/Timer functionalities and not directly as a ADC/DAC sample clock.

Further, read on aggregate sampling - https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000kIz9SAE&l=en-US, 

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000P9DtSAK&l=en-US