Problems with Flexible Resolution on a NI5911

[Weez]

When I try to acquire data in Flexible Resolution Mode, I often obtain the Warning 3FFA4002 (Data acquired during the acquisition is possibly invalid...). I also try to acquire a sine wave using safety condition: Vpp of sine wave of 10V with maximum range of 20V, and frequency of 2 kHz with sample rate of 100 kS/s (bandwidth of 40 kHz), but I obtain always the same error. The generator that I use is the DS360 of the Stanford Research Systems.

[AlessioD]

Weez,
You should try to increase the SampleRate for that instrument. It might be a problem with a jitter on the trigger that is used internally for the acquisition.

Hope this helps,

AlessioD
National Instruments

[Weez]

Thanks, i resolved this problem.
I need to know a thing: in 'oscilloscope' mode the delta of the ADC is different from the nominal one (2*range/256). In fact it is greater, so the maximum value of the range (for exemple +-10V) is reached at 10.80-10.85. Is it normal?

[AlessioD]

Hi,
can you be more precise as to what specifications you are referring to? For complete specifications you should look at this document.

http://digital.ni.com/manuals.nsf/websearch/1455AA60B1D7D99E86256E1B00722841?OpenDocument&node=132100_US

Can you point out on this document what specification you are referring to?

AlessioD
National Instruments

[Weez]

I try to explain (if you are italian I prefer to write in my language, it's more simple):
if I set the vertical sensitivity (input range) to +-10V, the NI5911 begins to clip at 10.85V, and this is a strange thing.
In every input range the NI5911 clips about at 8-9% over the nominal value. Why this?

[AlessioD]

Weez,

try and contact our Technical Support team in Italy. We will be discussing your issue in deeper details.
Regards,

AlessioD
National Instruments