Waveform Chart X axis Controls

[Indiana_Bill]

Certainly this has been answered before but I haven't found the answer in the multitude of similar posts.  I am trying to display the output of DAQ analog inputs on a waveform chart.  The inputs are monitored continuously but only displyed while a software triggered event is in progress.  Things are all working except for my control of the X axis time and display.  The time range is preset from 2 to 30 seconds and should display in seconds.  I have been playing with:

XScale.Minimun                         Always 0

XScale.Maximun                        Desired time * Sample Rate

XScale.Increment                      1/ Sample Rate

Sample Rate                              1000 samples per second    (want to change to 100)                    

Chart History Length                 11500

At the moment things are working as desired except for the scale coming out in milliseconds and any change I make sends my display into a fast schroling mode.  How do I change the scale from milliseconds to seconds?  Are there other settings I need to control?  Is there documentation on X axis control that I have missed?

Sorry to repeat an old question.

William A (Bill) Monette

Indiana University, School of Optometry

[Gregory]

You can go into the chart properties and change the multiplier (also available as the XScale.Multiplier) property. You might want the multiplier to be 0.001 and have the increment be 1000. That way, every 1000 data points you should get a tick showing the number of seconds. The number on the X-axis is most likely the sample number. In the case of 1000 samples / second, that would indeed be milliseconds.

You shouldn't have to play with the minimum and maximum too much, the chart (not graph) will start scrolling automatically when it hits the maximum. If you are seeing funny behavior, it may be because you are setting these instead of letting them be automatic.

[Indiana_Bill]

Thanks for the input. 

Changing the XScale.Multiplier does indeed change the scale to the expected range (11 seconds for my current settings) but it also compresses the plot into 0 to 1.

A second point.  I don't want the chart to schroll.  The interesting part of the event is early, in fact I am thinking of stopping the display early and not displaying the entire event, and I want it to remain displayed while the remainded of the cycle continues.

Again, thanks for the idea.  Any other suggestions?

Bill

[Gregory]

You can change the "Display Format" to have the digits of precision that you desire. Also, in the bottom left of the "Scales" tab you can click the box to choose how you want the tick marks to look.

As for having the chart stop updating after the interesting part happens, that will have to be done by you because only you know what is interesting. If you don't need to see every point as it is plotted, you can use a graph instead to show all of your data after you record it.

[Indiana_Bill]

Well, things seem to be working.  Your initial suggestion, the XScale.Multiplier, was the key.  Why it did what it did the first time I tried it or why it now seems to work is still a mystery but at this point I will go on to other problems.

Thank you for your response.

Bill

[Gregory]

You're welcome, feel free to give kudos and mark a solution if it helped you.

[pratik.dip]

Can you tell me how to create the control for x scale range in labview? Because when I am creating the the x scale range from property node of a graph, it is creating as an output, not as an input... 

[Dennis_Knutson]

This is basic LabVIEW that you should have learned from some of the free tutorials. Right click on the property node. See where it says change to write?