NI 9263 specifications

[bertrobb]

I am working with very accurate signals. I am using an internal clock to control the operation on a NI 9263 DAC output. I am seeing a drift on a saw-tooth signal that is running at 500ms. The drift is running faster compared to my function generator by about 44ms per 10 minutes. Do you know the specification of the NI 9263 DAC? Does this fall within the tolerance?

Thanks,

Bert

[Sean_F]

Hi Bert,

Thanks for posting! If I understand this correctly, what you're describing is expected. If the timebase used to generated the sample clock on the 9263 is different from the one used in your function generator than you will see a phase shift over time. Despite the fact that both devices may say they're generating at X Samples/sec this is not exact. The jitter and accuracy specs of the clocks will determine how far out of spec these clocks can drift from their true value. Another thing to keep in mind is that there is a discreet set of valid sample clock rates available on the 9263. These rates are obtained by dividing down a timebase in you cDAQ chassis. If a requested sample rate is not available, the DAQmx driver will coerce the sample clock to the nearest valid sample clock rate. To find out what rate your device is actually sampling at, use the SampClk.Rate property in the DAQmx Timing property node (see below). Hope this helps!

[Sean_F]

Just a quick correction, the property node should be changed to read: