Aperture Time incorrect for NI 4071 @ 4.5 digits

[JLAnderson]

I wrote a program to determine what the aperture times are for the NI 4071 DMM and found the 4.5 digit time does not match the specification.  The specification states 50 us but the actual value returned is 20 us (The same as the 4070/4072 meters).  The 3.5 digit resolution returns the same answer as 4.5 digits and is not specified.  I don't see how 3.5 and 4.5 digits resolution can have the same accuracy.  The code in C# used:

NI_4071.ConfigureMeasurementDigits(Function, Range, Digits);

NI_4071.SetDouble(niDMMProperties.AcMinFreq, "", 10E3);

NI_4071.GetDouble(niDMMProperties.ApertureTime, "");

DC Current and Ohms gave the same answers as DC volts.  AC volts and current gave the same answers.

Also does autorange use 500 us regardless of what range it finally ends up on?

This means autorange is significantly less accurate than using 6.5 or 7.5 digits.

John Anderson

[Izzzzz]

Hello John, 

Thanks for letting me know about this post. If it is okay with you let us keep our correspondance limited to that page. I will go ahead and leave a link to the other post on this page so anyone with a similar quesiton can follow along. 

Regards,

Izzy O.

Applications Engineer

National Instruments 

[JLAnderson]

OK with me.  I just thought the other thread was getting very long.  Katie also created another generic version of the thread.

John Anderson