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modbus_sniffer.py
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#!/usr/bin/env python
"""
Python modbus sniffer implementation
---------------------------------------------------------------------------
The following is an modbus RTU sniffer program,
made without the use of modbus specific library.
"""
# --------------------------------------------------------------------------- #
# import the various needed libraries
# --------------------------------------------------------------------------- #
import signal
import sys
import getopt
import logging
import serial
# --------------------------------------------------------------------------- #
# configure the logging system
# --------------------------------------------------------------------------- #
class myFormatter(logging.Formatter):
def format(self, record):
if record.levelno == logging.INFO:
self._style._fmt = "%(asctime)-15s %(message)s"
elif record.levelno == logging.DEBUG:
self._style._fmt = f"%(asctime)-15s \033[36m%(levelname)-8s\033[0m: %(message)s"
else:
color = {
logging.WARNING: 33,
logging.ERROR: 31,
logging.FATAL: 31,
}.get(record.levelno, 0)
self._style._fmt = f"%(asctime)-15s \033[{color}m%(levelname)-8s %(threadName)-15s-%(module)-15s:%(lineno)-8s\033[0m: %(message)s"
return super().format(record)
log = logging.getLogger()
handler = logging.StreamHandler()
handler.setFormatter(myFormatter())
log.setLevel(logging.INFO)
log.addHandler(handler)
# --------------------------------------------------------------------------- #
# declare the sniffer
# --------------------------------------------------------------------------- #
class SerialSnooper:
def __init__(self, port, baud=9600, timeout=0):
self.port = port
self.baud = baud
self.timeout = timeout
log.info("Opening serial interface: \n" + "\tport: {} \n".format(port) + "\tbaudrate: {}\n".format(baud) + "\tbytesize: 8\n" + "\tparity: none\n" + "\tstopbits: 1\n" + "\ttimeout: {}\n".format(timeout))
self.connection = serial.Serial(port=port, baudrate=baud, bytesize=serial.EIGHTBITS, parity=serial.PARITY_NONE, stopbits=serial.STOPBITS_ONE, timeout=timeout)
log.debug(self.connection)
# Global variables
self.data = bytearray(0)
self.trashdata = False
self.trashdataf = bytearray(0)
def __enter__(self):
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self.close()
def open(self):
self.connection.open()
def close(self):
self.connection.close()
def read_raw(self, n=1):
return self.connection.read(n)
# --------------------------------------------------------------------------- #
# Bufferise the data and call the decoder if the interframe timeout occur.
# --------------------------------------------------------------------------- #
def process_data(self, data):
if len(data) <= 0:
if len(self.data) > 2:
self.data = self.decodeModbus(self.data)
return
for dat in data:
self.data.append(dat)
# --------------------------------------------------------------------------- #
# Debuffer and decode the modbus frames (Request, Responce, Exception)
# --------------------------------------------------------------------------- #
def decodeModbus(self, data):
modbusdata = data
bufferIndex = 0
while True:
unitIdentifier = 0
functionCode = 0
readAddress = 0
readQuantity = 0
readByteCount = 0
readData = bytearray(0)
writeAddress = 0
writeQuantity = 0
writeByteCount = 0
writeData = bytearray(0)
exceptionCode = 0
crc16 = 0
request = False
responce = False
error = False
needMoreData = False
frameStartIndex = bufferIndex
if len(modbusdata) > (frameStartIndex + 2):
# Unit Identifier (Slave Address)
unitIdentifier = modbusdata[bufferIndex]
bufferIndex += 1
# Function Code
functionCode = modbusdata[bufferIndex]
bufferIndex += 1
# FC01 (0x01) Read Coils FC02 (0x02) Read Discrete Inputs
if functionCode in (1, 2):
# Request size: UnitIdentifier (1) + FunctionCode (1) + ReadAddress (2) + ReadQuantity (2) + CRC (2)
expectedLenght = 8 # 8
if len(modbusdata) >= (frameStartIndex + expectedLenght):
bufferIndex = frameStartIndex + 2
# Read Address (2)
readAddress = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# Read Quantity (2)
readQuantity = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# CRC16 (2)
crc16 = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
metCRC16 = self.calcCRC16(modbusdata, bufferIndex)
bufferIndex += 2
if crc16 == metCRC16:
if self.trashdata:
self.trashdata = False
self.trashdataf += "]"
log.info(self.trashdataf)
request = True
responce = False
error = False
if functionCode == 1:
functionCodeMessage = 'Read Coils'
else:
functionCodeMessage = 'Read Discrete Inputs'
log.info("Master\t\t-> ID: {}, {}: 0x{:02x}, Read address: {}, Read Quantity: {}".format(unitIdentifier, functionCodeMessage, functionCode, readAddress, readQuantity))
modbusdata = modbusdata[bufferIndex:]
bufferIndex = 0
else:
needMoreData = True
if (request == False):
# Responce size: UnitIdentifier (1) + FunctionCode (1) + ReadByteCount (1) + ReadData (n) + CRC (2)
expectedLenght = 7 # 5 + n (n >= 2)
if len(modbusdata) >= (frameStartIndex + expectedLenght):
bufferIndex = frameStartIndex + 2
# Read Byte Count (1)
readByteCount = modbusdata[bufferIndex]
bufferIndex += 1
expectedLenght = (5 + readByteCount)
if len(modbusdata) >= (frameStartIndex + expectedLenght):
# Read Data (n)
index = 1
while index <= readByteCount:
readData.append(modbusdata[bufferIndex])
bufferIndex += 1
index += 1
# CRC16 (2)
crc16 = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
metCRC16 = self.calcCRC16(modbusdata, bufferIndex)
bufferIndex += 2
if crc16 == metCRC16:
if self.trashdata:
self.trashdata = False
self.trashdataf += "]"
log.info(self.trashdataf)
request = False
responce = True
error = False
if functionCode == 1:
functionCodeMessage = 'Read Coils'
else:
functionCodeMessage = 'Read Discrete Inputs'
log.info("Slave\t-> ID: {}, {}: 0x{:02x}, Read byte count: {}, Read data: [{}]".format(unitIdentifier, functionCodeMessage, functionCode, readByteCount, " ".join(["{:02x}".format(x) for x in readData])))
modbusdata = modbusdata[bufferIndex:]
bufferIndex = 0
else:
needMoreData = True
else:
needMoreData = True
# FC03 (0x03) Read Holding Registers FC04 (0x04) Read Input Registers
elif functionCode in (3, 4):
# Request size: UnitIdentifier (1) + FunctionCode (1) + ReadAddress (2) + ReadQuantity (2) + CRC (2)
expectedLenght = 8 # 8
if len(modbusdata) >= (frameStartIndex + expectedLenght):
bufferIndex = frameStartIndex + 2
# Read Address (2)
readAddress = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# Read Quantity (2)
readQuantity = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# CRC16 (2)
crc16 = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
metCRC16 = self.calcCRC16(modbusdata, bufferIndex)
bufferIndex += 2
if crc16 == metCRC16:
if self.trashdata:
self.trashdata = False
self.trashdataf += "]"
log.info(self.trashdataf)
request = True
responce = False
error = False
if functionCode == 3:
functionCodeMessage = 'Read Holding Registers'
else:
functionCodeMessage = 'Read Input Registers'
log.info("Master\t-> ID: {}, {}: 0x{:02x}, Read address: {}, Read Quantity: {}".format(unitIdentifier, functionCodeMessage, functionCode, readAddress, readQuantity))
modbusdata = modbusdata[bufferIndex:]
bufferIndex = 0
else:
needMoreData = True
if (request == False):
# Responce size: UnitIdentifier (1) + FunctionCode (1) + ReadByteCount (1) + ReadData (n) + CRC (2)
expectedLenght = 7 # 5 + n (n >= 2)
if len(modbusdata) >= (frameStartIndex + expectedLenght):
bufferIndex = frameStartIndex + 2
# Read Byte Count (1)
readByteCount = modbusdata[bufferIndex]
bufferIndex += 1
expectedLenght = (5 + readByteCount)
if len(modbusdata) >= (frameStartIndex + expectedLenght):
# Read Data (n)
index = 1
while index <= readByteCount:
readData.append(modbusdata[bufferIndex])
bufferIndex += 1
index += 1
# CRC16 (2)
crc16 = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
metCRC16 = self.calcCRC16(modbusdata, bufferIndex)
bufferIndex += 2
if crc16 == metCRC16:
if self.trashdata:
self.trashdata = False
self.trashdataf += "]"
log.info(self.trashdataf)
request = False
responce = True
error = False
if functionCode == 3:
functionCodeMessage = 'Read Holding Registers'
else:
functionCodeMessage = 'Read Input Registers'
log.info("Slave\t-> ID: {}, {}: 0x{:02x}, Read byte count: {}, Read data: [{}]".format(unitIdentifier, functionCodeMessage, functionCode, readByteCount, " ".join(["{:02x}".format(x) for x in readData])))
modbusdata = modbusdata[bufferIndex:]
bufferIndex = 0
else:
needMoreData = True
else:
needMoreData = True
# FC05 (0x05) Write Single Coil
elif (functionCode == 5):
# Request size: UnitIdentifier (1) + FunctionCode (1) + WriteAddress (2) + WriteData (2) + CRC (2)
expectedLenght = 8
if len(modbusdata) >= (frameStartIndex + expectedLenght):
bufferIndex = frameStartIndex + 2
# Write Address (2)
writeAddress = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# Write Data (2)
writeData.append(modbusdata[bufferIndex])
bufferIndex += 1
writeData.append(modbusdata[bufferIndex])
bufferIndex += 1
# CRC16 (2)
crc16 = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
metCRC16 = self.calcCRC16(modbusdata, bufferIndex)
bufferIndex += 2
if crc16 == metCRC16:
if self.trashdata:
self.trashdata = False
self.trashdataf += "]"
log.info(self.trashdataf)
request = True
responce = False
error = False
log.info("Master\t-> ID: {}, Write Single Coil: 0x{:02x}, Write address: {}, Write data: [{}]".format(unitIdentifier, functionCode, writeAddress, " ".join(["{:02x}".format(x) for x in writeData])))
modbusdata = modbusdata[bufferIndex:]
bufferIndex = 0
else:
needMoreData = True
if (request == False):
# Responce size: UnitIdentifier (1) + FunctionCode (1) + WriteAddress (2) + CRC (2)
expectedLenght = 6
if len(modbusdata) >= (frameStartIndex + expectedLenght):
bufferIndex = frameStartIndex + 2
# Write Address (2)
writeAddress = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# CRC16 (2)
crc16 = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
metCRC16 = self.calcCRC16(modbusdata, bufferIndex)
bufferIndex += 2
if crc16 == metCRC16:
if self.trashdata:
self.trashdata = False
self.trashdataf += "]"
log.info(self.trashdataf)
request = False
responce = True
error = False
log.info("Slave\t-> ID: {}, Write Single Coil: 0x{:02x}, Write address: {}".format(unitIdentifier, functionCode, writeAddress))
modbusdata = modbusdata[bufferIndex:]
bufferIndex = 0
else:
needMoreData = True
# FC06 (0x06) Write Single Register
elif (functionCode == 6):
# Request size: UnitIdentifier (1) + FunctionCode (1) + WriteAddress (2) + WriteData (2) + CRC (2)
expectedLenght = 8
if len(modbusdata) >= (frameStartIndex + expectedLenght):
bufferIndex = frameStartIndex + 2
# Write Address (2)
writeAddress = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# Write Data (2)
writeData.append(modbusdata[bufferIndex])
bufferIndex += 1
writeData.append(modbusdata[bufferIndex])
bufferIndex += 1
# CRC16 (2)
crc16 = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
metCRC16 = self.calcCRC16(modbusdata, bufferIndex)
bufferIndex += 2
if crc16 == metCRC16:
if self.trashdata:
self.trashdata = False
self.trashdataf += "]"
log.info(self.trashdataf)
request = True
responce = False
error = False
log.info("Master\t-> ID: {}, Write Single Register: 0x{:02x}, Write address: {}, Write data: [{}]".format(unitIdentifier, functionCode, writeAddress, " ".join(["{:02x}".format(x) for x in writeData])))
modbusdata = modbusdata[bufferIndex:]
bufferIndex = 0
else:
needMoreData = True
if (request == False):
# Responce size: UnitIdentifier (1) + FunctionCode (1) + WriteAddress (2) + WriteData (2) + CRC (2)
expectedLenght = 8
if len(modbusdata) >= (frameStartIndex + expectedLenght):
bufferIndex = frameStartIndex + 2
# Write Address (2)
writeAddress = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# Write Data (2)
writeData.append(modbusdata[bufferIndex])
bufferIndex += 1
writeData.append(modbusdata[bufferIndex])
bufferIndex += 1
# CRC16 (2)
crc16 = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
metCRC16 = self.calcCRC16(modbusdata, bufferIndex)
bufferIndex += 2
if crc16 == metCRC16:
if self.trashdata:
self.trashdata = False
self.trashdataf += "]"
log.info(self.trashdataf)
request = False
responce = True
error = False
log.info("Slave\t-> ID: {}, Write Single Register: 0x{:02x}, Write address: {}, Write data: [{}]".format(unitIdentifier, functionCode, writeAddress, " ".join(["{:02x}".format(x) for x in writeData])))
modbusdata = modbusdata[bufferIndex:]
bufferIndex = 0
else:
needMoreData = True
# FC07 (0x07) Read Exception Status (Serial Line only)
# elif (functionCode == 7):
# FC08 (0x08) Diagnostics (Serial Line only)
# elif (functionCode == 8):
# FC11 (0x0B) Get Comm Event Counter (Serial Line only)
# elif (functionCode == 11):
# FC12 (0x0C) Get Comm Event Log (Serial Line only)
# elif (functionCode == 12):
# FC15 (0x0F) Write Multiple Coils
elif (functionCode == 15):
# Request size: UnitIdentifier (1) + FunctionCode (1) + WriteAddress (2) + WriteQuantity (2) + WriteByteCount (1) + WriteData (n) + CRC (2)
expectedLenght = 10 # n >= 1
if len(modbusdata) >= (frameStartIndex + expectedLenght):
bufferIndex = frameStartIndex + 2
# Write Address (2)
writeAddress = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# Write Quantity (2)
writeQuantity = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# Write Byte Count (1)
writeByteCount = modbusdata[bufferIndex]
bufferIndex += 1
expectedLenght = (9 + writeByteCount)
if len(modbusdata) >= (frameStartIndex + expectedLenght):
# Write Data (n)
index = 1
while index <= writeByteCount:
writeData.append(modbusdata[bufferIndex])
bufferIndex += 1
index += 1
# CRC16 (2)
crc16 = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
metCRC16 = self.calcCRC16(modbusdata, bufferIndex)
bufferIndex += 2
if crc16 == metCRC16:
if self.trashdata:
self.trashdata = False
self.trashdataf += "]"
log.info(self.trashdataf)
request = True
responce = False
error = False
log.info("Master\t-> ID: {}, Write Multiple Coils: 0x{:02x}, Write address: {}, Write quantity: {}, Write data: [{}]".format(unitIdentifier, functionCode, writeAddress, writeQuantity, " ".join(["{:02x}".format(x) for x in writeData])))
modbusdata = modbusdata[bufferIndex:]
bufferIndex = 0
else:
needMoreData = True
else:
needMoreData = True
if (request == False):
# Responce size: UnitIdentifier (1) + FunctionCode (1) + WriteAddress (2) + WriteQuantity (2) + CRC (2)
expectedLenght = 8
if len(modbusdata) >= (frameStartIndex + expectedLenght):
bufferIndex = frameStartIndex + 2
# Write Address (2)
writeAddress = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# Write Quantity (2)
writeQuantity = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# CRC16 (2)
crc16 = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
metCRC16 = self.calcCRC16(modbusdata, bufferIndex)
bufferIndex += 2
if crc16 == metCRC16:
if self.trashdata:
self.trashdata = False
self.trashdataf += "]"
log.info(self.trashdataf)
request = False
responce = True
error = False
log.info("Slave\t-> ID: {}, Write Multiple Coils: 0x{:02x}, Write address: {}, Write Quantity: {}".format(unitIdentifier, functionCode, writeAddress, writeQuantity))
modbusdata = modbusdata[bufferIndex:]
bufferIndex = 0
else:
needMoreData = True
# FC16 (0x10) Write Multiple registers
elif (functionCode == 16):
# Request size: UnitIdentifier (1) + FunctionCode (1) + WriteAddress (2) + WriteQuantity (2) + WriteByteCount (1) + WriteData (n) + CRC (2)
expectedLenght = 11 # n >= 2
if len(modbusdata) >= (frameStartIndex + expectedLenght):
bufferIndex = frameStartIndex + 2
# Write Address (2)
writeAddress = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# Write Quantity (2)
writeQuantity = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# Write Byte Count (1)
writeByteCount = modbusdata[bufferIndex]
bufferIndex += 1
expectedLenght = (9 + writeByteCount)
if len(modbusdata) >= (frameStartIndex + expectedLenght):
# Write Data (n)
index = 1
while index <= writeByteCount:
writeData.append(modbusdata[bufferIndex])
bufferIndex += 1
index += 1
# CRC16 (2)
crc16 = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
metCRC16 = self.calcCRC16(modbusdata, bufferIndex)
bufferIndex += 2
if crc16 == metCRC16:
if self.trashdata:
self.trashdata = False
self.trashdataf += "]"
log.info(self.trashdataf)
request = True
responce = False
error = False
log.info("Master\t-> ID: {}, Write Multiple registers: 0x{:02x}, Write address: {}, Write quantity: {}, Write data: [{}]".format(unitIdentifier, functionCode, writeAddress, writeQuantity, " ".join(["{:02x}".format(x) for x in writeData])))
modbusdata = modbusdata[bufferIndex:]
bufferIndex = 0
else:
needMoreData = True
else:
needMoreData = True
if (request == False):
# Responce size: UnitIdentifier (1) + FunctionCode (1) + WriteAddress (2) + WriteQuantity (2) + CRC (2)
expectedLenght = 8
if len(modbusdata) >= (frameStartIndex + expectedLenght):
bufferIndex = frameStartIndex + 2
# Write Address (2)
writeAddress = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# Write Quantity (2)
writeQuantity = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# CRC16 (2)
crc16 = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
metCRC16 = self.calcCRC16(modbusdata, bufferIndex)
bufferIndex += 2
if crc16 == metCRC16:
if self.trashdata:
self.trashdata = False
self.trashdataf += "]"
log.info(self.trashdataf)
request = False
responce = True
error = False
log.info("Slave\t-> ID: {}, Write Multiple registers: 0x{:02x}, Write address: {}, Write quantity: {}".format(unitIdentifier, functionCode, writeAddress, writeQuantity))
modbusdata = modbusdata[bufferIndex:]
bufferIndex = 0
else:
needMoreData = True
if (request == False) & (responce == False):
# Error size: UnitIdentifier (1) + FunctionCode (1) + ExceptionCode (1) + CRC (2)
expectedLenght = 5 # 5
if len(modbusdata) >= (frameStartIndex + expectedLenght):
bufferIndex = frameStartIndex + 2
# Exception Code (1)
exceptionCode = modbusdata[bufferIndex]
bufferIndex += 1
# CRC16 (2)
crc16 = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
metCRC16 = self.calcCRC16(modbusdata, bufferIndex)
bufferIndex += 2
if crc16 == metCRC16:
if self.trashdata:
self.trashdata = False
self.trashdataf += "]"
log.info(self.trashdataf)
request = False
responce = False
error = True
log.info("Slave\t-> ID: {}, Write Multiple registers: 0x{:02x}, Exception: {}".format(unitIdentifier, functionCode, exceptionCode))
modbusdata = modbusdata[bufferIndex:]
bufferIndex = 0
else:
needMoreData = True
# FC17 (0x11) Report Server ID (Serial Line only)
# elif (functionCode == 17):
# FC20 (0x14) Read File Record
# elif (functionCode == 20):
# FC21 (0x15) Write File Record
# elif (functionCode == 21):
# FC22 (0x16) Mask Write Register
# elif (functionCode == 22):
# FC23 (0x17) Read/Write Multiple registers
elif (functionCode == 23):
# Request size: UnitIdentifier (1) + FunctionCode (1) + ReadAddress (2) + ReadQuantity (2) + WriteAddress (2) + WriteQuantity (2) + WriteByteCount (1) + WriteData (n) + CRC (2)
expectedLenght = 15 # 13 + n (n >= 2)
if len(modbusdata) >= (frameStartIndex + expectedLenght):
bufferIndex = frameStartIndex + 2
# Read Address (2)
readAddress = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# Read Quantity (2)
readQuantity = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# Write Address (2)
writeAddress = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# Write Quantity (2)
writeQuantity = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
bufferIndex += 2
# Write Byte Count (1)
writeByteCount = modbusdata[bufferIndex]
bufferIndex += 1
expectedLenght = (13 + writeByteCount)
if len(modbusdata) >= (frameStartIndex + expectedLenght):
# Write Data (n)
index = 1
while index <= writeByteCount:
writeData.append(modbusdata[bufferIndex])
bufferIndex += 1
index += 1
# CRC16 (2)
crc16 = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
metCRC16 = self.calcCRC16(modbusdata, bufferIndex)
bufferIndex += 2
if crc16 == metCRC16:
if self.trashdata:
self.trashdata = False
self.trashdataf += "]"
log.info(self.trashdataf)
request = True
responce = False
error = False
log.info("Master\t-> ID: {}, Read/Write Multiple registers: 0x{:02x}, Read address: {}, Read Quantity: {}, Write address: {}, Write quantity: {}, Write data: [{}]".format(unitIdentifier, functionCode, readAddress, writeAddress, readQuantity, writeQuantity, " ".join(["{:02x}".format(x) for x in writeData])))
modbusdata = modbusdata[bufferIndex:]
bufferIndex = 0
else:
needMoreData = True
else:
needMoreData = True
if (request == False):
# Responce size: UnitIdentifier (1) + FunctionCode (1) + ReadByteCount (1) + ReadData (n) + CRC (2)
expectedLenght = 7 # 5 + n (n >= 2)
if len(modbusdata) >= (frameStartIndex + expectedLenght):
bufferIndex = frameStartIndex + 2
# Read Byte Count (1)
readByteCount = modbusdata[bufferIndex]
bufferIndex += 1
expectedLenght = (5 + readByteCount)
if len(modbusdata) >= (frameStartIndex + expectedLenght):
# Read Data (n)
index = 1
while index <= readByteCount:
readData.append(modbusdata[bufferIndex])
bufferIndex += 1
index += 1
# CRC16 (2)
crc16 = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
metCRC16 = self.calcCRC16(modbusdata, bufferIndex)
bufferIndex += 2
if crc16 == metCRC16:
if self.trashdata:
self.trashdata = False
self.trashdataf += "]"
log.info(self.trashdataf)
request = False
responce = True
error = False
log.info("Slave\t-> ID: {}, Read/Write Multiple registers: 0x{:02x}, Read byte count: {}, Read data: [{}]".format(unitIdentifier, functionCode, readByteCount, " ".join(["{:02x}".format(x) for x in readData])))
modbusdata = modbusdata[bufferIndex:]
bufferIndex = 0
else:
needMoreData = True
else:
needMoreData = True
# FC24 (0x18) Read FIFO Queue
# elif (functionCode == 24):
# FC43 ( 0x2B) Encapsulated Interface Transport
# elif (functionCode == 43):
# FC80+ ( 0x80 + FC) Exeption
elif (functionCode >= 0x80):
# Error size: UnitIdentifier (1) + FunctionCode (1) + ExceptionCode (1) + CRC (2)
expectedLenght = 5 # 5
if len(modbusdata) >= (frameStartIndex + expectedLenght):
bufferIndex = frameStartIndex + 2
# Exception Code (1)
exceptionCode = modbusdata[bufferIndex]
bufferIndex += 1
# CRC16 (2)
crc16 = (modbusdata[bufferIndex] * 0x0100) + modbusdata[bufferIndex + 1]
metCRC16 = self.calcCRC16(modbusdata, bufferIndex)
bufferIndex += 2
if crc16 == metCRC16:
if self.trashdata:
self.trashdata = False
self.trashdataf += "]"
log.info(self.trashdataf)
request = False
responce = False
error = True
log.info("Slave\t-> ID: {}, Exception: 0x{:02x}, Code: {}".format(unitIdentifier, functionCode, exceptionCode))
modbusdata = modbusdata[bufferIndex:]
bufferIndex = 0
else:
needMoreData = True
else:
needMoreData = True
if needMoreData:
return modbusdata
elif (request == False) & (responce == False) & (error == False):
if self.trashdata:
self.trashdataf += " {:02x}".format(modbusdata[frameStartIndex])
else:
self.trashdata = True
self.trashdataf = "\033[33mWarning \033[0m: Ignoring data: [{:02x}".format(modbusdata[frameStartIndex])
bufferIndex = frameStartIndex + 1
modbusdata = modbusdata[bufferIndex:]
bufferIndex = 0
# --------------------------------------------------------------------------- #
# Calculate the modbus CRC
# --------------------------------------------------------------------------- #
def calcCRC16(self, data, size):
crcHi = 0XFF
crcLo = 0xFF
crcHiTable = [ 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
0x80, 0x41, 0x00, 0xC1, 0x81, 0x40]
crcLoTable = [ 0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06,
0x07, 0xC7, 0x05, 0xC5, 0xC4, 0x04, 0xCC, 0x0C, 0x0D, 0xCD,
0x0F, 0xCF, 0xCE, 0x0E, 0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09,
0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9, 0x1B, 0xDB, 0xDA, 0x1A,
0x1E, 0xDE, 0xDF, 0x1F, 0xDD, 0x1D, 0x1C, 0xDC, 0x14, 0xD4,
0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3,
0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3,
0xF2, 0x32, 0x36, 0xF6, 0xF7, 0x37, 0xF5, 0x35, 0x34, 0xF4,
0x3C, 0xFC, 0xFD, 0x3D, 0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A,
0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38, 0x28, 0xE8, 0xE9, 0x29,
0xEB, 0x2B, 0x2A, 0xEA, 0xEE, 0x2E, 0x2F, 0xEF, 0x2D, 0xED,
0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26,
0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60,
0x61, 0xA1, 0x63, 0xA3, 0xA2, 0x62, 0x66, 0xA6, 0xA7, 0x67,
0xA5, 0x65, 0x64, 0xA4, 0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F,
0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB, 0x69, 0xA9, 0xA8, 0x68,
0x78, 0xB8, 0xB9, 0x79, 0xBB, 0x7B, 0x7A, 0xBA, 0xBE, 0x7E,
0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5,
0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71,
0x70, 0xB0, 0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92,
0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C,
0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E, 0x5A, 0x9A, 0x9B, 0x5B,
0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89, 0x4B, 0x8B,
0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C,
0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42,
0x43, 0x83, 0x41, 0x81, 0x80, 0x40]
index = 0
while index < size:
crc = crcHi ^ data[index]
crcHi = crcLo ^ crcHiTable[crc]
crcLo = crcLoTable[crc]
index += 1
metCRC16 = (crcHi * 0x0100) + crcLo
return metCRC16
# --------------------------------------------------------------------------- #
# Print the usage help
# --------------------------------------------------------------------------- #
def printHelp(baud, timeout):
if timeout == None:
timeout = calcTimeout(baud)
print("\nUsage:")
print(" python modbus_sniffer.py [arguments]")
print("")
print("Arguments:")
print(" -p, --port select the serial port (Required)")
print(" -b, --baudrate set the communication baud rate, default = {} (Option)".format(baud))
print(" -t, --timeout override the calculated inter frame timeout, default = {}s (Option)".format(timeout))
print(" -h, --help print the documentation")
print("")
# print(" python3 {} -p <serial port> [-b baudrate, default={}] [-t timeout, default={}]".format(sys.argv[0], baud, timeout))
# --------------------------------------------------------------------------- #
# Calculate the timeout with the baudrate
# --------------------------------------------------------------------------- #
def calcTimeout(baud):
# Modbus states that a baud rate higher than 19200 must use a 1.75 ms for a frame delay.
# For baud rates below 19200 the timeing is more critical and has to be calculated.
# In modbus a character is made of a data byte that appends a start bit, stop bit,
# and parity bit which mean in RTU mode, there are 11 bits per character.
# Though the "Character-Time" calculation is 11 bits/char / [baud rate] bits/sec.
# Modbus standard states a frame delay must be 3.5T or 3.5 times longer than
# a normal character.
# E.g. for 9600 baud:
# "Character-Time": 11 / 9600 = 0.0011458s
# "Frame delay": 11 * 3.5 = 38.5
# 38.5 / 9600 = 0.0040104s
if (baud < 19200):
timeout = 33 / baud # changed the ratio from 3.5 to 3
else:
timeout = 0.001750
return timeout
# --------------------------------------------------------------------------- #
# configure a clean exit (even with the use of kill,
# may be useful if saving the data to a file)
# --------------------------------------------------------------------------- #
def signal_handler(sig, frame):
print('\nGoodbye\n')
sys.exit(0)
# --------------------------------------------------------------------------- #
# main routine
# --------------------------------------------------------------------------- #
if __name__ == "__main__":
print(" ")
# init the signal handler for a clean exit
signal.signal(signal.SIGINT, signal_handler)
port = None
baud = 9600
timeout = None
try:
opts, args = getopt.getopt(sys.argv[1:],"hp:b:t:",["help", "port=", "baudrate=", "timeout="])
except getopt.GetoptError as e:
log.debug(e)
printHelp(baud, timeout)
sys.exit(2)
for opt, arg in opts:
if opt in ("-h", "--help"):
printHelp(baud, timeout)
sys.exit()
elif opt in ("-p", "--port"):
port = arg
elif opt in ("-b", "--baudrate"):
baud = int(arg)
elif opt in ("-t", "--timeout"):
timeout = float(arg)
if port == None:
print("Serial Port not defined please use:")
printHelp(baud, timeout)
sys.exit(2)
if timeout == None:
timeout = calcTimeout(baud)
with SerialSnooper(port, baud, timeout) as sniffer:
while True:
data = sniffer.read_raw()
sniffer.process_data(data)