hello @glv thank you for triggering me 
,
I’ve done an exploration using the Arduino code you gave, and comment/uncomment the print on the processing statement. Based on the results I got, everything is the same as shown in the image below.
for Serial.println() is print data to console as a newline
But why null shows up, i still don’t understand.
I try with a combination like this, there is no null, is it clear?
