import serial, math
 
ser = serial.Serial(port='COM6', baudrate=115200, bytesize=serial.EIGHTBITS, 
    parity=serial.PARITY_NONE, timeout=1)

while not ser.readable():
    print(":", end="")
    
#txt = ser.readline().decode()  #
txt = ser.read_until('\n') #.decode() 
print(txt)

while True:
    txt = ser.readline().decode()
    print(txt)