Measuring an ac signal using the PXI-4498

[A_Aardvarkie]

I am measuring the output from a device using the PXI-4498. However, when i attach the 4498 channel zero, for example, the voltage being measured is reduced. It looks like the input impedance of the 4498 is too low (although it is reported to be 10MOhm). However, I haven't found how to turn off the IEPE ecitation for any of the channels. Could this be responsible ?

[Rob_Ward]

Dear A_Aardvarkie

Here is a KB article on "IEPE Excitation Levels for DSA Devices" ( http://digital.ni.com/public.nsf/allkb/3FAC9D4707C661208625716A005BFE32?OpenDocument ) that you may find useful.

It seems as though you can alter the IEPE settings programatically or by configuration settings in MAX. The following KnowledgeBase article goes through how to enable or disable IEPE settings using both methods.

"How Do I Enable IEPE Excitation Programatically?" ( http://digital.ni.com/public.nsf/allkb/D2D5A38279AA1431862576F20061DEEF?OpenDocument)

Kind Regards,