Develop Reference

Python connection with a Device through serial port

I need help with a python code to connect with a Router or a Switch via serial port. I use pycharm from a Windows terminal.
This is what I tried:
import keyboard
ser = serial.Serial(port="COM1", baudrate=9600, bytesize=8, timeout=2, stopbits=serial.STOPBITS_ONE)
while True:
ser.write('You got connected\r\n'.encode('Ascii'))
receive = ser.readline()
print(receive.decode('Ascii'))
if keyboard.is_pressed('q'):
print('User need to quit the app.')
break
ser.close()
Tried and I got errors.

What error do you get ?
This would be very helpful if you could copy/paste your errors in here.

python pyserial read data and respond

I am trying to open a serial port connection and keep it open as long as data if communicating. I also want to respond if certain data is received. Below is an example of the python script. I am able to open the serial port send data and the script responds, it will not respond with the elif data.
I am new to pyserial and have been working on python lately but not great by any means.
Thank you
import serial
import time
ser = serial.Serial('/dev/ttyUSB0', timeout=10) # open serial port
print(ser.name) # check which port was really used
response = ser.read()
if response == (b'\r'):
ser.write (b'ID=')
elif response == (b'\r\r\x1bPG1\r'):
ser.write (b'110 1.8<CR><ACK><CR><ESC>[p<CR>')
#time.sleep(5)
#print ()
#ser.close() # close port

How to read and write from a COM Port using PySerial?

I have Python 3.6.1 and PySerial Installed. I am trying the
I am able to get the list of comports connected. I now want to be able to send data to the COM port and receive responses back. How can I do that? I am not sure of the command to try next.
Code:
import serial.tools.list_ports as port_list
ports = list(port_list.comports())
for p in ports:
print (p)
Output:
COM7 - Prolific USB-to-Serial Comm Port (COM7)
COM1 - Communications Port (COM1)
I see from the PySerial Documentation that the way to open a COM Port is as below:
import serial
>>> ser = serial.Serial('/dev/ttyUSB0') # open serial port
>>> print(ser.name) # check which port was really used
>>> ser.write(b'hello') # write a string
>>> ser.close() # close port
I am running on Windows and I get an error for the following line:
ser = serial.Serial('/dev/ttyUSB0')
This is because '/dev/ttyUSB0' makes no sense in Windows. What can I do in Windows?

This could be what you want. I'll have a look at the docs on writing.
In windows use COM1 and COM2 etc without /dev/tty/ as that is for unix based systems. To read just use s.read() which waits for data, to write use s.write().
import serial
s = serial.Serial('COM7')
res = s.read()
print(res)
you may need to decode in to get integer values if thats whats being sent.

On Windows, you need to install pyserial by running
pip install pyserial
then your code would be
import serial
import time
serialPort = serial.Serial(
port="COM4", baudrate=9600, bytesize=8, timeout=2, stopbits=serial.STOPBITS_ONE
)
serialString = "" # Used to hold data coming over UART
while 1:
# Wait until there is data waiting in the serial buffer
if serialPort.in_waiting > 0:
# Read data out of the buffer until a carraige return / new line is found
serialString = serialPort.readline()
# Print the contents of the serial data
try:
print(serialString.decode("Ascii"))
except:
pass
to write data to the port use the following method
serialPort.write(b"Hi How are you \r\n")
note:b"" indicate that you are sending bytes

How to read data from serial port? Python

Hi please bear my basic question as I am new to python.
I am trying to read data from serial port. Basically serial port is a USB port converted to serial port virtually. I am using arduino.
First i tried this code:
while(True):
ser=serial.Serial('COM6',9600)
bytoread=ser.inWaiting()
val=ser.read(bytoread)
But it gave me error.
Permission Error(13,Access is denied, none 5)
But when i changed my code to
while(True):
ser=serial.Serial()
ser.baudrate=19600
ser.port='COM6'
ser
ser.open()
bytoread=ser.inWaiting()
val=ser.read(bytoread)
Permission error did not come but program is always busy connecting the port. I waited for many minutes but it never moved forward. What I am doing wrong here?

you can do something like :
import serial
ser = serial.Serial('COM6', 9600, timeout=None)
while True:
data = ser.readline()
you can't put ser = serial.Serial('COM5', 9600, timeout=None) in your while loop because it will permanently (re)create the connection...

Error in working with pyserial module of python

import time
import serial
# configure the serial connections (the parameters differs on the device you are connecting to)
ser = serial.Serial(
port='/dev/ttyS0',
#port='/dev/ttyACM0',
baudrate=115200,
parity=serial.PARITY_ODD,
#stopbits=serial.STOPBITS_TWO,
#bytesize=serial.SEVENBITS
)
ser.isOpen() # returns true
time.sleep(1);
ser.write("some_command \n")
ser.close()
I have a embedded board. It has a serial port which is connected to my computer. I am running above script to access this serial port and run some board specific commands.
My problem
I open my serial port (using minicom in linux) separately and then run above script, It works. If I don't open serial port separately, Script doesn't work.

try
ser.write("some_command \n".encode())
alternatively try
ser.write(bytes(b"some_command \n"))