01-10-2011 11:09 AM
I'm using a 4071 DMM that has a DC offset on the current measurement (10mA scale). I can't use the Autozero function because I'm getting a waveform. Is there a way to get the value used by the Autozero function so I can subtract that from the waveform?
George
01-11-2011 04:47 PM - edited 01-11-2011 04:50 PM
Hello GS,
I would recommend using the NI Soft Front Panel (SFP); Null Offset feature.This feature stores the current reading of the DMM and subtructs it from any future readings. The stored offset is shown on the display and you can reset it by disabling/enabling it. The NI DMM SFP can be found by navigating to Windows Start>All Programs>National Instruments>NI DMM>Soft Front Panel.
Best regards,
Ali M
Applications Engineer
National Instruments
01-12-2011 07:17 AM
Thanks, but I really need to get it programatically to include in my program.
01-13-2011 06:03 AM
Why not calculate the DC bias by yourself?
Did you went through the instrument specific properties?
I don't have a 4071, so I couldn't tell if this value is stored seperatly, and how it is recovered.
01-13-2011 11:34 AM
Have you actually tried using AutoZero with waveform mode? I used to be on the NI-DMM software team and it seems like autozero with waveforms were supported. If I'm remembering correctly, the autozero measurement was taken once at the beginning and then used for the entire waveform.
Mark S.
Former NI-DMM Software
01-13-2011 11:40 AM
The help specifically says that autozero doesn't work with waveforms.
01-13-2011 12:42 PM
I don't see where it says it's not supported? I see where AUTO will turn it OFF in waveform mode, but I really do believe you can turn it on explicitly. I'm looking at the niDMM Configure Auto Zero help. Is there another help page you are looking at that says something different?
Mark S.
01-13-2011 01:58 PM
Maybe I misintrepreted how it works in waveform mode. When it said it turned it off, I figured that meant it turned of Autozero altogether. So if I configure Autozero to be On instead of Auto will it stay on for waveform mode?
01-13-2011 02:38 PM
Yes. From the way I read that paragraph and from what I remember of the implementation, it is describing what the driver will do if you set autozero to auto in those configurations. If your use case requires a different behavior than that provided by auto, you can explicitly set it to on, off, or once depending on your need.
Mark S.