analog input problem

[sam B]

Problems with analog input

We want to measure an analog input signal. Therefore we use an example project from labview: “Analog input”.

Everything works fine but when we generate a sine wave at 50Hz on the analog input channel of the NI9215, we get strange results.

The sine wave doesn’t look at all like a sine wave.

Different configuration of the parameters in the Analog Input VI (sample rate, software loop time) never shows the sine wave we expect. 

It looks like the sample rate is to low…

 Hardware configuration:

-          compactRIO NI9012

-          analog input device: NI9215

-       connection between compactRIO and PC: UTP (Ethernet connection)

thanks

[Christian Mergl]

And how does the measured signal look like? maybe you can post a screenshot.

Thanks,

Christian

[sam B]

In attachments you will find a sine wave at 20 Hz frequency with a sample rate of 10kHz.

[Christian Mergl]

Hey,

It seems that you changed a bit of the examples code, it looks different to the one I know.

However you have a control which says AI Sample Rate = 20Hz, what rate is that? you said you sample the signal with 10kHz?

When you just open the origin Analog Input project, configure it for your hardware and run it, can you see a sine wave?

Christian

[sam B]

On the figure we have a sample rate of 20Hz, but when we increase the sample rate to 10kHz we just get the same waveform...nothing changes

We work with the original example as found in the LabView library.

[Christian Mergl]

My origin example looks like that:

[sam B]

Can you attach this example to a reply?

[Christian Mergl]

Just open the Example Finder in LabVIEW (Help>Find Examples) and search for "analog" then you find a project called "Analog Input-cRIO.lvproj".

Christian