pull data from scope & save to a file

[Dennis_Knutson]

Sorry, I didn't read one of your previous posts all that closely and I wasn't clear enough in my description. You should not have deleted the Initialize function. You should just disable the reset input to it. Wire a false and it will skip the reset but still open a VISA session to the instrument. If you still get this error with the initialize, then check that the scope is defined correctly in MAX.

[jjlee]

I was able to get a waveform in a graph!! (thanks!)

A couple of questions

1. time (X-axis) on graph displays between 0 and 2E-7 and this really crams the whole waveform  on the left 1/8 of the area...how can I change the x-axis scale??

2. the file generated shows all wrong time stamp value....where do I need to look to correct this?

Asking above 2 questions, x-axis shown on graph and what it is exported in a file seems not matching (???)

[jjlee]

I am not sure how I can retrieve x-axis points other than time stamp as it is shown in my previous posting. Does anyone have any experience with this type of problem? Perhaps, I will need to back calculate to obtain this(?)I

[Dennis_Knutson]

I just think the problem is how the Export Waveforms to Spreadsheet File is formatting the time data. Since the header as the correct dt, it looks like it's just a matter of precision in the conversion to strings. I'll admit that I haven't used the Export function that much. You can dig into it to see where the time to string conversion is happening and change the precision or cimply calculate the time stamps yourself and use Write to Spreadsheet file. LabVIEW also has the Write LabVIEW Measurements File function but I think that might have the same issue with precision. Building a time array is trivial. See the attachment.

Message Edited by Dennis Knutson on 03-22-200604:05 PM

[jjlee]

Actually, I am trying to find out how I can get x-axis points from scope.

Two vertical cursors on each end of the scope screen shows t1 and t2 corresponds to 19ns & 39ns.

Obviously, turning the 'horizontal position' and 'scale' knob would change these t1 and t2 range.

So, how can I get this horizontal axis data  points from the scope? (so that I have a corresponding x-axis points for each Y value)

[Dennis_Knutson]

You are getting it. The X offset and X Increment. If you don't want to create a waveform data type, bundle the information from the scope per the help for a graph. With this information the graph should scale correctly. You probably need to change the formatting of the X axis. Right click on the graph and select X Scale>Formatting. Try setting it to Scientific.

Message Edited by Dennis Knutson on 03-23-200610:43 AM

[jjlee]

I think I am still getting the same results after using 'Build Arrray' to concatenate (x offset, x increment, waveform array)

Now the time (x-axis) displays 0 to 550...tried different formatting...but it did not help...

[Dennis_Knutson]

That's not the Build Array but the Bundle function and you are bundling in the wrong order. You have to do it in exactly the same order as what the help says (x0,dx,y).

[jjlee]

Tried it with the bundle function, but could not display the waveform...

BTW, how can I synch up  'return points' in 'Get waveform_mod.vi' to 'Record Length' setting in the scope?

I wonder not setting any default value for 'return points' would do the trick(?)

[Dennis_Knutson]

I don't know what went wrong with your bundle. You would have to create indicators for each output, run it, save as defaults, save the VI, and then re-post.

You are specifying a 500 point transfer I believe with the waveform size control. The return points should be the same unless you've set the record length to be less. I think there is another function for setting the scope's record length.