You can't change the number of plots without loosing the data history. You could read the chart history property then manipulate the 2D array, add the new data, then update the history data again. A simpler alternative if you know the maximum number of channels you are likely to need, is to set up a dummy 1D array of NaN's then when you get your data, use 'Replace Array Subset' vi to add your variable data to the chart. Take a look at my example.
Hope this helps.
Ian
