Serial fuzzer written in Python3

fuzzer.py

#!/usr/bin/env python3

import serial
import binascii

# Open serial port
ser = serial.Serial(
   port=input("Enter the USB /dev port"),
   baudrate=115200,
   timeout=0.005
)


def read_serial(ser):
   ''' Read any output it might have produced'''
   output = bytearray()
   while True:
       inp = ser.read(size=1) #read a byte
       output += inp

       if len(inp) < 1:
           return bytearray(output)


def send_command(command):
   ''' Push out a command to the serial port, get data back '''
   output = bytearray()
   for byte in command:
       ser.write([byte])
       output += read_serial(ser)

   return output


def increment(counter):
   carry = 0
   for i in range(len(counter)):
       byte = counter[i]

       if byte == 255:
           byte = 0
           carry = 1
       elif carry == 1:
           byte += carry
           carry = 0
       else:
           byte += 1

       counter[i] = byte

       if carry is not 1:
           break

   return counter


counter = [0, 0, 0, 0, 0, 0, 0]
print()
while True:
   message = bytearray(counter)
   print("\rSending:  {0} ".format(binascii.hexlify(message)), end='')
   response = send_command(message)
   if len(response) > 0:
       print("\nReceived: {0}\n".format(binascii.hexlify(response)))

   counter = increment(counter)