time stamp x-axis

[JTH]

I have several NI/LV systems that display plots of data  (slowly-varying analog inputs to a USB 6008) vs time step, but I would like to use real time on the x axis.  The top plot in the attached vi is similar to what I'm doing now.  It seems like the bottom plot should do what I want, but the its x axis is frozen in 1903.

[Dennis_Knutson]

There is no attachment. If you click on preview post, you have to re-attach.

[JTH]

I have several NI/LV systems that display plots of data  (slowly-varying analog inputs to a USB 6008) vs time step, but I would like to use real time on the x axis.  The top plot in the attached vi is similar to what I'm doing now.  It seems like the bottom plot should do what I want, but the its x axis is frozen in 1903.

[Dennis_Knutson]

You still didn't attach anything!

[Nick_F1]

Hi JTH,

Thank you for posting on the National Instruments forums. 
Are you still having an issue with the x-axis in your application?  If you would attach your vi, I can take a look at it and assist you in figuring out what is going on with your program.

[JTH]

Nick -

Thanks for the response.  I'm having trouble on 2 fronts: 1) the original problem of making the x-axis plot real time; and 2) attaching my prototype vi to my message. 

Please let me know when you see this posting, and whether or not there is an attachment.

Thanks again.

[AnalogKid2DigitalMan]

The attachment did indeed attach

[Dennis_Knutson]

The bottom plot in the attached example does display the actual time. It is not frozen at 1903. The top plot, however, does not correctly display elapsed time. Because you have a non-waveform data type wired to the chart, the dt of the chart is using the default of 1. You can use a chart property called XScale>Offset and Multiplier>Multiplier and set it to your loop iteration time. Since you don't have a wait function that sets the iteration time, you should add one and use that value. The offset can also be set. Look at the shipping example called Real-Time Chart. Also, the way you have those 4 1D arrays wired to a single Build Waveform function is not correct. A waveform has a single Y array. If you want 4 separate waveforms plotted, you need 4 separate Build Waveform functions.