Saving a relative chart time.

[Tim 152]

I noticed that when taking data the time displayed on the chart is moving slower then actual time. The other data displayed in the chart appears to have good response however. I suppose for the time being I can live with only having relative time as long as all displays are somewhat synchronized on display. I am trying to write all my data to a fileto graph in excel but dont want to use real time as a synch cause it seams that the relative time displayed by the chart is goes with the data. I dont know exactly how this data is synched in time. Any help would be great. Thanks so much.

[Philip_Courtois]

Hi Tim,

The x-axis on your Waveform Chart is controlled by the Loop Delay and the XScale.Multiplier. In case the code in your loop takes longer than the Loop Delay, the loop will not continue until next iteration of the Loop Delay. This could cause some timing issues, since the code inside the loop may have non-consisting execution times.

You can include a timestamp to your data using the timing functions, and that way make sure that the x-scale will be relative to the time � being absolute or relative.


I hope this answered your question.

Best regards,
Philip C.
Applications Engineer
National Instruments
www.ni.com/ask