Change External Sampling Clock Takes A Long Time on PXIe-5186

[YuYiming]

Hi,

I am using the Lv Example -- niScope EX External Clocking.vi to set PXIe-5186 using an external sampling clock.  However it takes a long time, 5-6 minutes,  before I can get the first block of the acquisition data.

Then I run the "niScope EX Configured Acquisition.vi" example to switch to the on board clock. It also takes 5-6 minutes on the first acquisition.

I think maybe the PXIe-5186 is doing some calibration when I change the clock source. 

Is there anyway to skip the calibration ? Or make it faster ?

Many Thanks

Yiming

[Nathan-P · Accepted solution]

Yiming,

The delays in the acquisition are caused by calibration routines that need to be run on the sampling engine (ADC) each time the sample rate changes.  This ensures our warrented accuracy specifications.  

I'm not sure if you also noticed the Power-Up Calibration, which will take 5-10min to complete when the device is powered on.  This is mentioned in our specifications on page 18:

http://www.ni.com/pdf/manuals/373257b.pdf#Page=18

I hope this helps.

Nathan

[YuYiming]

Thank you very much for your help.