XY graph multi plot live points and colour control

Question

Hi All,
I'm trying to do something that should be simple but is proving to be difficult so far. I have had a good look through previous topics and found things similar but not actually what I want.
In my experiment I scan intensity vs wavelength.
Ideally I want to be able to:
1)  run a scan and see the points plotted live.
2) Then I want the plot to stay on the graph when I run the next scan, etc.
3) I'd like to do an arbitrary number of scans. e.g. To initiate a scan I press a button, an arbitrary number of times.  
4) I want to make it so that the current scan is plotted live in one colour (red), and all the previous scans remain plotted in another colour (blue).
5) Sometimes I may want to clear the graph of all scans and begin again, without having to stop the VI.
Items 1-3 can be taken care of easily by placing the Build XY graph and XY graph object inside the for loop that runs the scan, and unticking 'Clear data on each call' in the propertes of Build graph. See first attached VI.
However, at the beginning of a scan it joins the last point of the previous scan to the first point of the next scan.
The difficult parts are 4 and 5.
For item 4 you need to build an array of plots, which is easy if you know the number of plots, but here the number is arbitrary. So how do I do that? I've had a go by trying to use Insert Array in different ways but I haven't worked it out. Then hopefully using the XY graph property nodes I can set the colours of the plots.
For part 5 it is not enough just to use the invoke node = reinitialize to default, and have a button that executes the node. This clears the graph but then when you run the next scan all the previous plots pop up again, indicating that the array that stores the plots is not actually cleared. The second attachment shows how I'm clearing the graph.
My biggest problem is item 4, and combining item 4 and 5 together.
Please help. 
Solved!
Go to Solution.
Attachments:
Current method_Items 1-3.vi ‏18 KB
Item 5 idea_with no item 4.vi ‏18 KB

Answer 1

The key is understanding the data type. If you hover over the graph's terminal, you will see that multiple plots are simply an array of single plots. Once you know that, something like this quick modification is fairly easy to come up with. I also added events to make it more readable. Note that this isn't actually a good way of doing things (for instance, you can't abort the drawing in the middle), but it shows the graph concept. You might wish to look at some code like producer/consumer designs.
As for the colors, you're right that the properties can help you there. I will leave it to you to figure out the exact properties, but when you start a new plot, you will basically want to reset all the others to white and make the new one red.
Try to take over the world!
Attachments:
XY Chart.vi ‏17 KB