Saving potential solution to my problem with the AB so far: the instance of AM0DProcessVariableDataSource doesn't actually have a values() method, not pure virtual in AMDataSource (?). So just calling value() instead from STRealtimeModelAB::onInputSourceValuesChanged() to get the latest pv update.
So far, so good. Am able to create an AMDataSourceSeriesData instance from STRealtimeModelAB and plug it into a MPlotSeriesBasic. Will it plot?
Nope. Single point appears at (0, 0) with no updates.
I had made a mistake with checking index rank in STRealtimeModelAB::values(). Fixed now, a single point is still plotted (boo) but now it reflects the storage ring current value and updates.
Playing around with the analysis block class, still not working quite as it's supposed to. The class is accumulating values as it should, but there seems to be a problem with reporting values to the series class that plots the data. Right now, project builds and runs. A single point is plotted at (0, 0)--no update. Keep using AM1DSummingAB as reference.