NI DMM Swtich does not autorange

[jfeetham]

I am using a NI PXI 4070 DMM 3.0.2 driver along with LabView 9.1. I am trying to make DC measurements using the NI-DMM/Switch Express function from LabView. When I select the properties, I get an option to set Auto Range. I would like to use autorange, but when I select it then close the properties dialog and reselect the properties dialog, it reverts back to "Specifiy Range" and 5 1/2 digits. This causes out of range measurement errors.

[Efrain_G]

Hi there,

I was able to reproduce that behavior in LabVIEW 2010 NI DMM 3.0.3. I will go ahead and notify our R&D departmnet about this. Have you tried to measure a voltage without changing the properties of the NI-DMM/Switch Express VI?

[jfeetham]

We are able to measure a voltage most of the time. But we do get an out of range error. We are using the erase error function to allow our software to move on. This is a temporary fix however. We would like the driver to work correctly. Another data point for you. When we get down to the sub-VI level of this funciton there is an option for autorange. From the VI defintion for the Range function it looks as if a -1 is the correct setting for autorange. It looks as if this setting remains at this level, but the VI still produces the out of range error that we are handling with the erase error function.

[GarPar]

Hi jfeetham-

     The autorange function starts at the lowest selectable range of the DMM and attempts a reading.  If the value is out of range, the DMM moves to the next highest range and attempts again.  This continues until the DMM is at an appropriate range.

     That being said, is your voltage value actually out of range?  Is this error unexpected?

[jfeetham]

We get the voltage we expect. It is the out of range error that we have to deal with using the erase error function.  I am still unsure if the DMM is really autoranging?  There is the issue with the high level properties described in my first communication. This along with the error causes me to question the autoranging function

My second communication looks at the lower level VI. It is this level that indicates that the DMM should be autoranging, but it still doesn't seem like it.

Hope this helps.

[GarPar]

jfeetham-

     Can you post a screenshot of your code?  If you have the value set to -1, then the DMM should autorange.  The issue with your express VI has been reported to R&D as a Corrective Action Request (CAR).

     If you post a screenshot of your code and a screenshot of the error you are receiving, it may help us understand a little better what is going on.  Have a happy holiday season!