Loading issue with NI PXIe 4499

[ehsan11]

Hi,

I am using NI PXIe 4499 and I see this card has an effect my analog reading.
Just as an experiment , I used a function generator to generate a sine wave (
1v amp ) and used NI PXIe 4461 and 4499 to acquire the generated signal. As can
be seen in the attached images the 4461 gives me a correct reading but as soon
as I connect 4499 I see this loading effect and significant drop in voltage .
Could you please let me know how can I set the input impedance of 4499 or is
there any specific setting for this card. I self calibrated the card as well
but I still see this loading effect

Thanks,

[MCOTO]

Hello,

Please refer to the Analog Input section (page 2-2) of the NI Dynamic Signal Acquisition User Manual. Either the Channel Configuration or the Input Coupling could be affecting your measurement.

 “Using AC coupling results in an attenuation of the low-frequency response of the AI circuitry.

Refer to the NI USB-443x Specifications, NI 446x Specifications, NI 447x Specifications, and

NI 449x Specifications for information about the cut-off frequency for each device.”

Regards,

MCOTO