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Need help with DAQmxGetDevAIGains

Could someone please give me an example of how to use DAQmxGetDevAIGains?  Like many functions in the DAQmx C API, I can find only the barest of documentation.  The documentation shows:

 

    int32 __CFUNC DAQmxGetDevAIGains(const char device[], float64 *data, uInt32 arraySizeInSamples);

        Purpose

        DAQmxGetDevAIGains gets the I/O Type >> Analog Input >> Gains property

 

I tried using it like so:

 

    double gains[32];

    int err = DAQmxGetDevAIGains("PXI2Slot2", gains, 32);

 

where the device at PXI2Slot2 is a PXI-6250.  The call returns with err == 0, but the gains array is filled with garbage (-7.8e+298).  I've already created a task and at least one AI channel before I try to get the gains.  What am I doing wrong?

 

Thanks,

Larry

 

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Hi Larry,

I am familiar with a similar property that I can use withoput problem in LabVIEW. Let me if I can find an example in C that will help us figure out what you are doing wrong. I will post back monday afternoon with an update.

 

What environment are you programming in? If you would like to, you could also post your code and I can take a look at it.

Regards,

Mallori

Mallori M
National Instruments
Sr Group Manager, Education Services

ni.com/training
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AI Gain is pretty much only used on SCXI devices so when you query it for for available gains on a regular DAQ card it just returns an empty array. What you're probably looking for is DAQmxGetDevAIVoltageRngs().

 

Cheers, 

Andrew S

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Hi Larry,

He makes a good point. I believe I have only used the Gains property node with Dynamic Signal Acquisition (DSA) cards and SCXI in the past. Some links that you might find helpful with regards to DAQmxGetDevAIVoltageRngs() are:

Format of DAQmxGetDevAIVoltageRngs

how to list AI input ranges by daqmx

I hope this helps,

Mallori

Mallori M
National Instruments
Sr Group Manager, Education Services

ni.com/training
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