Serial Communication Using Python

Python is a widely used high-level, general-purpose, interpreted, dynamic programming language. Its design philosophy emphasizes code readability, and its syntax allows programmers to express concepts in fewer lines of code than possible in languages such as C++ or Java. The language provides constructs intended to enable clear programs on both a small and large scale.

Python supports multiple programming paradigms, including object-oriented,imperative and functional programming or procedural styles. It features a dynamic type system and automatic memory management and has a large and comprehensive standard library.

Python interpreters are available for many operating systems, allowing Python code to run on a wide variety of systems. Using third-party tools, such as Py2exe or Py installer, Python code can be packaged into stand-alone executable programs for some of the most popular operating systems, so Python-based software can be distributed to, and used on, those environments with no need to install a Python interpreter.

We won't go in much details, as an Embedded Electronics Engineer serial communication is important to us and in the following section we will see how we can achieve this. The code provided below is self explanatory and can be used as base to do serial communication in Python with your embedded device.

Python doesn't have any library for serial communication, so before proceeding further we have to install the PySerial package, which can be done easily with the help of few commands.

For Python 3.x:

• Open Command Prompt and type
  pip3 install pyserial
  This command will download and install the PySerial package from internet.

Install PySerial for Python 3.x

 For Python 2.7.x:

• Open Command Prompt and type
  pip install pyserial
  This command will download and install the PySerial package from internet.

Install PySerial for Python 2.7.x

Once the PySerial package is installed, open the python GUI (IDLE) and type the command "import serial", if it doesn't give any error, then it means PySerial library is successfully installed.

Get the List of available Serial Ports:
To get the list of available serial ports, use the following commands from the python terminal and it will gives you the list of all available serial ports on your PC.
Python 3.x:

>>> import serial.tools.list_ports as port_list
>>> ports = list(port_list.comports())
>>> for p in ports: print (p)

COM2 - Communications Port (COM2)
COM1 - ELTIMA Virtual Serial Port (COM1->COM5)
COM5 - ELTIMA Virtual Serial Port (COM5->COM1)
COM3 - ELTIMA Virtual Serial Port (COM3->COM6)
COM6 - ELTIMA Virtual Serial Port (COM6->COM3)
COM4 - ELTIMA Virtual Serial Port (COM4->COM7)
COM7 - ELTIMA Virtual Serial Port (COM7->COM4)

>>> 

List of Ports in Python 3

 Python 2.7.x:

>>> import serial.tools.list_ports as port_list
>>> ports = list(port_list.comports())
>>> for p in ports: print p

COM2 - Communications Port (COM2)
COM1 - ELTIMA Virtual Serial Port (COM1->COM5)
COM5 - ELTIMA Virtual Serial Port (COM5->COM1)
COM3 - ELTIMA Virtual Serial Port (COM3->COM6)
COM6 - ELTIMA Virtual Serial Port (COM6->COM3)
COM4 - ELTIMA Virtual Serial Port (COM4->COM7)
COM7 - ELTIMA Virtual Serial Port (COM7->COM4)

>>> 

List of Ports in Python 2.7.x

The following video will demonstrate the results of the code given below.

import serial

#Can be Downloaded from this Link

#https://pypi.python.org/pypi/pyserial

#Global Variables

ser = 0

#Function to Initialize the Serial Port

def init_serial():

    COMNUM = 1          #Enter Your COM Port Number Here.

    global ser          #Must be declared in Each Function

    ser = serial.Serial()

    ser.baudrate = 9600

    ser.port = COMNUM - 1   #COM Port Name Start from 0

   

    #ser.port = '/dev/ttyUSB0' #If Using Linux

    #Specify the TimeOut in seconds, so that SerialPort

    #Doesn't hangs

    ser.timeout = 10

    ser.open()          #Opens SerialPort

    # print port open or closed

    if ser.isOpen():

        print 'Open: ' + ser.portstr

#Function Ends Here

       

#Call the Serial Initilization Function, Main Program Starts from here

init_serial()

temp = raw_input('Type what you want to send, hit enter:\r\n')

ser.write(temp)         #Writes to the SerialPort

while 1:    

    bytes = ser.readline()  #Read from Serial Port

    print 'You sent: ' + bytes      #Print What is Read from Port

   

If you want to use Serial Communication using Python in Linux or on Raspberry Pi, then click here. This tutorial is written for Raspberry Pi and will work for Linux OS.