Only if i could get how to loop each line of strings.
At the end of function
serialEvent I see - int newValue = Integer.parseInt(incomingValues[i].trim());
here you have a for-loop that goes through the entries of one line.
Does it work?
You need to println newValue and check whether it is ok. Then use newValue in some way.
see also for a linear graphic
https://forum.processing.org/topic/heart-rate-visual#25080000001835283