Hello Patrick,
From what you say I understand that you need to characterize an ADC, is that correct? If that were the case, then in order to obtain the behavior graph, I'd suggest you sweep a voltage using an AO pin and read its output using a DO port. Additionally, you'd have to create a data set that defines its ideal behavior (which I think is what you mean by "I have all code transition levels in array"). After you have both data sets (graphs), then you can easily mathematically compute in order to obtain both Differential and Integral Non-linearities.
If any of the information above was useful at all, please let me know.
Best regards.
