controling wavefrom graphs and instrument display.

[mrish]

Hello, 

I'm tring to control an old Optical Spectrum Analyzer (OSA) using VISA.

I manage to read and write and present the date - but not to see the OSA display screen!  I will explain:

The OSA sweep over some spectrum range continuously - the display actually shows a video. 

when the sweep ends it store the data in an array - which I read and show on a wavefrom graph.  This is where the OSA display and my waveform link breaks.

for example if I input a command to change the scale of the y-axis or to insert a marker, the OSA display is changed but not my waveform.  I could not find any other way to read the data.

from your exprience - such instruments (mine is 20 years old) offer a way to read the entire screen data somehow?

if not, how can I control my waveform graph through my program - for example define the y scale to be the same as that of the instrument?

[Dennis_Knutson]

What's the make and model of the instrument? Did you search for a driver (Help> Find Instrument Drivers)?

The instrument has to return the scale information and you have to create a cluster with x0, dx, and Y and pass that to the graph. After changing any instrument parameter, you would obviously need to re-read.

[mrish]

MY OSA is HP70951A.

I have programming manual of similar item for which most commands work - no driver is available, I've search.

I have a cluster of x0, dx and Y and I read the data correctly -  so far so good, but I do not see the instrument display at is.

for example: I could place a marker on my instrument display - but I wouldn't see it in my computer since I read only the y-axis data.

you can say - so read the marker as well, but what is the point - In theory I can seat in front of my computer screen and add marker on my waveform alone without the instrument. same as changing the y scale division - it will be changed on the instrument display or computer display seperatly.

I don't know if I'm asking too much....or this is how it should be since this is the first time I write a driver with labview.

P.S

I also ask about program control on waveform display in another forum - it is not so trivial for example to change the scaling based on input values in the program comapre to do it with some mouse click.  there are many properites node which are not well explained.