how to change units of X-Axis for historical Chart?

[TREMBALY]

In Hisctorical chart, I need to display X-Axis as distance in meters and and not in function of time. How can I change the way it is displayed?

Best regards.

[Ipshita_C]

Hi Trembaly,

Have you tried using an XY-graph instead? The waveform charts and graphs are set to show the X-xis as time by default. 

Ipshita C.

[Dennis_Knutson]

I'm not sure what you mean by historical chart. With the LabVIEW Waveform Chart, the 'time' on the x axis is just a label. It can be anything you want. Double click on it to change it. What it has to be is evenly sampled data. If you take data point every 1 meter, then just edit the label. If you take a data point at a different interval, change the label and the chart multiplier. For unevenly sampled data, you would want to use the XY Graph. Again, the x axis name is just a label.

[TREMBALY]

Thanks for answering me.

I give you some more details.

A USB6210 acquires 2 LVDT signals and 1 counter signal from encoder.

I computer the lenght of the cable with pulses from encoder.

I must draw two different graphs. One for the  first LVDT, its max and min limits vs Lenght and a Second graph with the second LVDT, its max and min vs Lenght.

Signals are sampled at 77hz and I adisplay about 5000 feet of datas on screen (the last about 1 minute range). About 30 minutes must be saved. At the end, the entire datas are displayed on graph.

It's important to keep a real time display when running the machine because it is use to determine the quality of the product. The speed directly affects the X-axis.

What is the best design? XY graph or WaveformChart?

Best regards.

[Ipshita_C]

Hi Trembaly,

Please look at this knowledgebase article to know the difference between a waveform graph and chart. Basically, a waveform graph gets drawn after the data has been collected and a waveform chart appends points as they come. Therefore, for your real-time display a waveform chart would be way to go. Hope this helps!

Ipshita C.

[TREMBALY]

Hi Ipshita C.,

That's what I've done for the first test. But I don't know how to set the X-axis as the lenght. Any example to send to me? 

[TREMBALY]

I need to enter 4 signals:

1- Max limit

2- Min Limit

3- LVDT

4- Length since starting.

Lenght should be the X-axis.

So each 0,013s, it take a snapshot of the values: LVDT and Lenght.

Lenght depends on the encoder (speed), not of the time interval. I cannot use Scale and Offset for the relationship.

[Dennis_Knutson]

With an XY Graph, you would have a display something like the image below (simulated LVDT and encoder read only). Is that what you want? If not, can you post an image of the type of plot you want?

[TREMBALY]

Here what the result looks like.

[Ipshita_C]

Hi Trembaly,

Please follow the post by Dennis for the XY-Graph and also look at the XY Graph example in the LabVIEW Example finder. Thanks!

Ipshita C.