import serial

# initialize serial connection
ser = serial.Serial(None, 115200, timeout=2)
# specify port separately to prevent auto-connecting
ser.port = 'COM3'

# open and print welcome message
ser.open()
welcome_message = ser.readlines()
print(welcome_message)

# close
ser.close()

# now open again
ser.open()
welcome_message = ser.readlines()
print(welcome_message) # <- im expecting this message to be empty.
# but apparently grbl reset, lost all coordinates, and shows welcome message again!