Agilent 4156c: getting NaN when trying to measure transconductance

[ClintN]

I don't see how any of my settings are incorrect; I'm using the exact same settings as when I run the instrument from the front panel and I have no issues.  For some reason, Labview doesn't like it when I try to measure the current on one variable while the voltage is held constant.  The same things happens if I try to measure the gate current when Vgs is biased at a particular value.  The front panel says Ig is on the order of nA, but through labview I get NaNs.

Clint

[amezam]

Hello ClintN,

Did you try the probes? I want to ensure that the data is coming well from the VIs and that the problem is not with the mathscript node. I know there’s a known issue when passing array data to a Formula Node, it may produce incorrect results. You said that you’re reading nA, in the front panel, do you need to configure settings in order to read such small values?

Best Regards,

Alina M

Applications Engineering

National Instruments

[ClintN]

amezam,

Yes, I tried the probes.  The data coming out of 'read trace data' is NaN, so the problem isn't with the mathscript node. 

ClintN

[nyc_(is_out_of_here)]

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@ClintN wrote:

I don't see how any of my settings are incorrect; I'm using the exact same settings as when I run the instrument from the front panel and I have no issues.  For some reason, Labview doesn't like it when I try to measure the current on one variable while the voltage is held constant.  The same things happens if I try to measure the gate current when Vgs is biased at a particular value.  The front panel says Ig is on the order of nA, but through labview I get NaNs.

Clint

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I would bet money it isn't a "LabVIEW problem".

Most likely you are not understanding what the individual VIs that you are using is telling the instrument to do.

Have you read the programmer's manual to understand what SCPI commands are meant to do? Have you looked inside the driver VIs to understand what exactly are the SCPI commands that are being sent.