Hello,
Processing is telling you that the COM7 port is busy; this suggests that the Arduino is connected to your Arduino monitor in your case.
You can make one serial connection with one Arduino COM port to one of these at a time:
- Arduino monitor
- Processing
- Another device or software
Try connecting the Arduino to Processing with and without the Arduino monitor connected and see what happens.
Try adding some code to receive the data that the Arduino is sending to Processing with the Serial.println() statement.
There are other options to get data from the Arduino; do a bit of research on this.
:)