if you are using pyserial module to read the communication from your device on UART , you will have to know which port the is your system connected to.
the following is a simple code to scan through all the COM ports and find out which com port is in opened. at the end of the program , you will see the serial uart that is in use being printed
for i in range(256):
s = serial.Serial(i)
available.append( (i, s.portstr))
port = i
ser = serial.Serial(port, 115200,timeout=1)