pySerial可以将数据时间发送到arduino

Question

I am trying to send date time to arduino using Python with serial communication, but I am having trouble sending the data. When I use var = raw_input ("input:") the data is sent. However when I use var = str (time.asctime (time.localtime (time.time ()))) the data not sent to arduino.

Here's my Python code:

import serial, time

port = serial.Serial('COM4',9600)
var = str(time.asctime(time.localtime(time.time())))
if port.isOpen():
   print ('Port Aktif')
   while 1:
       port.write(var)
       time.sleep(1)
       print port.readline()
else:
   print 'port Tidak Aktif'

my code arduino :

String msg ="";
void setup() {
   Serial.begin(9600); // set the baud rate

}
void loop() {
   if(Serial.available() > 0){
      while (Serial.available()>0){
         msg += char(Serial.read());
         delay(30);
      }
      Serial.println(msg);
   }
}

Answer 1

see https://pyserial.readthedocs.io/en/latest/pyserial_api.html#classes

it says:

write(data)
[...]
Write the bytes data to the port.
This should be of type bytes (or compatible such as bytearray or memoryview). 
Unicode strings must be encoded (e.g. 'hello'.encode('utf-8').

This means, use

var = bytes(time.asctime(time.localtime(time.time())).encode('utf-8'))

Answer 2

Instead of

In [1]: import time

In [2]: str(time.asctime(time.localtime(time.time())))
Out[2]: 'Sat May  6 14:39:17 2017'

use:

In [3]: time.asctime(time.localtime()).encode('utf-8')
Out[3]: b'Sat May  6 14:39:17 2017'

The latter will return a string of bytes, which is required when writing to a serial port.