I control an Arduino via Python using serial port, but the problem is that you can not stew the Arduino then via Serial Monitor in the Arduino IDE,
since the serial communication already from the Python busy. my question, does anyone know how to handle it ?, can Serial CAN-BUS module be an alternative?
I'm guessing that you need to use the SoftwareSerial library and a USB to TTL serial adaptor for the Python connection. This will allow you to continue using the IDE serial monitor window.
Another approach is to include some code in your Python program so it shows the messages it receives from the Arduino, That way you can see the messages without needing the Serial Monitor.