control output after run

[UofH]

I am pretty new to Labview. Can you tell me how to control the parameters in the output graph after running the VI ? What I mean to say is after getting a waveform output, I want to change the span and all and play with it. I could not figure out what drivers to use in GPIB on a optical spectrum analyzer

[LV_Pro]

Your question is a little unclear. You are asking how to control the parameters in the output graph but then you talk about changing the span and GPIB. For GPIB drivers you can go to the instrument driver network (https://www.ni.com/en/support/downloads/instrument-drivers.html) and search under the manufacturer for drivers (you will most likely be interested in VISA rather than those listed as IVI). If you are successful with that there will probably be an example of doing basic measurements using your instrument, allowing you to programmatically change the OSA's settings (such as Span, center wavelength, etc.). As to changing the output graph, if you are talking about one displayed in LabVIEW, you can modify the min/max amplitude values of the graph, use cursors to zoom in, etc.

P.M.

[falkpl]

Which version of labview?

[UofH]

Labview 7.1

[UofH]

As far as PMs reply,  I have the GPIB drivers for this instrument. I can progarmmatically change the span, center wavelength of the OSA. I was wondering if there is a way to play with span and all after output graph is displayed in Labview (i.e after the program is run) .
Like a knob where I can turn and correspondingly the span changes without the need of the program to run again with respect to the new span.

[LV_Pro]

You can look at your existing data, as displayed on the LabVIEW graph in various ways, using the cursors, etc., although if you want "knobs" to that you would have to program them, using their output to modify the graph's properties. It won't really be modifying the "span", just your view of the existing data. The graph cursors will allow you to zoom in, for instance, if there is some detail in the displayed data, but it won't change your resolution bandwidth or any of the actual data capture aspects that were set up on the OSA. The data you have is the data you have (well, new data can be derived from the existing, but that wasn't the question)

P.M.