Python Serial Writes to Arduino is different from Arduino's Serial Monitor's Serial Writes -

i have python script writes string test arduino serial port. if arduino receives test string, should reply string ok , led 13 should up..

problem: when arduino serial monitor used write test serial port, arduino replies ok expected , led #13 lights up.

however when python script writes test same serial port, nothing happens. arduino not reply serial port , led #13 not light up.

any ideas how python script can fixed ok response arduino , led 13 light up?

arduino sketch

int ledpin = 13;   void setup() {   serial.begin(9600);   pinmode(ledpin, output); }   void loop() {      while(serial.available() == 0) { }      if(serial.readstring() == "test\r\n") {       serial.print("ok\r\n");       digitalwrite(ledpin, high);     }       readstring = ""; // clear recieved buffer     delay(100); } 

python script

port = 'com5' ser = serial.serial(     port=port,     baudrate=9600,     timeout=5 )  serial.write("test\r\n")  response = serial.readline() print response 

port = 'com5' ser = serial.serial(     port=port,     baudrate=9600,     timeout=5 )  # need sleep after opening port few seconds time.sleep(5) # arduino takes few seconds ready ...  #also should write instance ser.write("test\r\n") # , give arduino time respond time.sleep(0.5) response = self.serial.readline() print response 

if dont want wait fixed number of seconds need wait ser.cts (clear send)