Display time stamped data from data file

[81452]

I'm practicing the handling a time stamped data - acquisition, store and (display later).
I could figure out the acqusition and the write to a data file but I couldn't make the display section.

Please advice me to display the stored data (time information - month, day, hour, minure and second
with some-three signals). For your reference, I attahed the vi which wrote data and the data file (small data - 8 columns and 14 rows). Thank you. -chung

Message Edited by 81452 on 06-08-2005 12:24 PM

[AESulzer]

From the setup of the front panel you posted it would appear that you want to display the data from file on a waveform chart, which actually won't be possible in this case and I will explain why. There are two ways (well, we'll simplify it to two) to graphically display data in LabVIEW: (1) Waveform graphs, and (2) XY Graphs. We'll first address the waveform graph that you've selected, but understanding it requires knowledge of what a waveform is.

A waveform is a datatype in LabVIEW that is composed of three things: (1) an array of data points, (2) a start time, and (3) a time interval (which is the time between each data point. That last item is the crux for you -- the data in a waveform graph must have an equal time spacing between all data points and your data does not fit this format.

To graph data that does not a have a consistent relationship along the x-axis, you will need to use an XY Graph. The XY Graph takes an array of x values and an array of y values and graphs them as coordinate pairs. This means that there does not have to be any dependecy between your data points. I would recommend taking a look at the shipping examples, XY Graph and Waveform Graph, for an illustration of how they work. You can find them through Example Finder in LabVIEW. Hope this clears things up!

Regards,