Not sure if you wanted to display multiple channels on one graph or actually display separate graphs.
19 Graphs on the one screen might get hard to read do you have an idea of a kind of layout you want to use?
Have a look at this example which might be something like your after.
It shows an example of letting the user select channels to display on a single graph and displaying multiple graphs using an array.
The array method doesn't update very well though and all graph properties have to be exactly the same.
You could also use re-entrant VIs that pop-up but this might get annoying to an operator too.
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Systems Test Engineer
Certified LabVIEW Architect (CLA)