2nd Try: Trouble writing lines to file that include line feeds - Newbie

[Dan Healy]

Overview: I'm attempting to read strings from a serial port. Each string ends with a carriage return and line feed. I want to write those strings to a file, like a log file. So, if I send P1 and the P2 on a new line, I would expect to open this file and find (line 1) P1 (line 2) P2. 

Problem: The file only contains P2. It always overwrites the first line. I can send 20 strings and the file will always contain the last string received. 

Code: 

#Import the serial module 
import serial 

#Open the serial port w/ settings 
ser=serial.Serial( 
        port="/dev/ttyUSB0", 
        baudrate=9600, 
        timeout=None) 

#Print data received on the serial port after removing the CR and LF characters 
while True: 
        rawcode=ser.readline() 
        codelog=open('/home/pi/avdms/codes.log','w') 
        codelog.write(rawcode) 
        codelog.close()