def build_request(self, pdu, slave):
"""Add the Modbus RTU part to the request"""
self._request_address = slave
if (self._request_address < 0) or (self._request_address > 255):
raise InvalidArgumentError("Invalid address {0}".format(self._request_address))
data = struct.pack(">B", self._request_address) + pdu
crc = struct.pack(">H", utils.calculate_crc(data))
return data + crc
def build_request(self, pdu, slave):
"""Add the Modbus RTU part to the request"""
self._request_address = slave
if (self._request_address < 0) or (self._request_address > 255):
raise InvalidArgumentError("Invalid address {0}".format(self._request_address))
data = struct.pack(">B", self._request_address) + pdu
crc = struct.pack(">H", utils.calculate_crc(data))
return data + crc
def testWriteSingleCoilInvalidValue(self):
"""Check that an error is raised when writing a coil with an invalid value"""
bad_query = struct.pack(">BBHH", 1, modbus_tk.defines.WRITE_SINGLE_COIL, 0, 1)
crc = struct.pack(">H", utils.calculate_crc(bad_query))
bad_query += crc
self.master.set_verbose(True)
self.master._send(bad_query)
response = self.master._recv()
self.assertEqual(response[:-2], struct.pack(">BBB", 1, modbus_tk.defines.WRITE_SINGLE_COIL+128, 3))
def testWriteSingleCoilInvalidValue(self):
"""Check that an error is raised when writing a coil with an invalid value"""
bad_query = struct.pack(">BBHH", 1, modbus_tk.defines.WRITE_SINGLE_COIL, 0, 1)
crc = struct.pack(">H", utils.calculate_crc(bad_query))
bad_query += crc
self.master.set_verbose(True)
self.master._send(bad_query)
response = self.master._recv()
self.assertEqual(response[:-2], struct.pack(">BBB", 1, modbus_tk.defines.WRITE_SINGLE_COIL+128, 3))
def compute_metric(self, trace):
import struct
incorrect_crc_count = 0
for pkt in trace.packets:
pkt_crc, = struct.unpack('>H',pkt.data[-2:])
correct_crc = modbus_utils.calculate_crc(pkt.data[:-2])
if pkt_crc != correct_crc:
incorrect_crc_count += 1
percent_incorrect = incorrect_crc_count/float(len(trace.packets))
return percent_incorrect
def parse_request(self, request):
"""Extract the pdu from the Modbus RTU request"""
if len(request) < 3:
raise ModbusInvalidRequestError("Request length is invalid {0}".format(len(request)))
(self._request_address, ) = struct.unpack(">B", request[0:1])
(crc, ) = struct.unpack(">H", request[-2:])
if crc != utils.calculate_crc(request[:-2]):
raise ModbusInvalidRequestError("Invalid CRC in request")
return self._request_address, request[1:-2]
def parse_request(self, request):
"""Extract the pdu from the Modbus RTU request"""
if len(request) < 3:
raise ModbusInvalidRequestError("Request length is invalid {0}".format(len(request)))
(self._request_address, ) = struct.unpack(">B", request[0:1])
(crc, ) = struct.unpack(">H", request[-2:])
if crc != utils.calculate_crc(request[:-2]):
raise ModbusInvalidRequestError("Invalid CRC in request")
return self._request_address, request[1:-2]
def testReadWithWrongFunction(self):
"""check that an error is raised when sending a query with an invalid function code"""
self.assertRaises(modbus_tk.modbus.ModbusFunctionNotSupportedError, self.master.execute, 1, 55, 0, 10)
bad_query = struct.pack(">BB", 1, 55)
crc = struct.pack(">H", utils.calculate_crc(bad_query))
bad_query += crc
try:
self.master._send(bad_query)
self.master._recv()
except modbus_tk.modbus.ModbusError, ex:
self.assertEqual(ex.get_exception_code(), 1)
return
def testReadWithWrongFunction(self):
"""check that an error is raised when sending a query with an invalid function code"""
self.assertRaises(modbus_tk.modbus.ModbusFunctionNotSupportedError, self.master.execute, 1, 55, 0, 10)
bad_query = struct.pack(">BB", 1, 55)
crc = struct.pack(">H", utils.calculate_crc(bad_query))
bad_query += crc
try:
self.master._send(bad_query)
self.master._recv()
except modbus_tk.modbus.ModbusError as ex:
self.assertEqual(ex.get_exception_code(), 1)
return
def parse_response(self, response):
"""Extract the pdu from the Modbus RTU response"""
#if len(response) < 3:
#raise ModbusInvalidResponseError("Response length is invalid {0}".format(len(response)))
(self._response_address, ) = struct.unpack(">B", response[0:1])
if self._request_address != self._response_address:
raise ModbusInvalidResponseError(
"Response address {0} is different from request address {1}".
format(self._response_address, self._request_address))
(crc, ) = struct.unpack(">H", response[-2:])
if crc != utils.calculate_crc(response[:-2]):
raise ModbusInvalidResponseError("Invalid CRC in response")
return response[1:-2]
def parse_response(self, response):
"""Extract the pdu from the Modbus RTU response"""
if len(response) < 3:
raise ModbusInvalidResponseError("Response length is invalid {0}".format(len(response)))
(self._response_address, ) = struct.unpack(">B", response[0])
if self._request_address != self._response_address:
raise ModbusInvalidResponseError(
"Response address {0} is different from request address {1}".format(
self._response_address, self._request_address
)
)
(crc, ) = struct.unpack(">H", response[-2:])
if crc != utils.calculate_crc(response[:-2]):
raise ModbusInvalidResponseError("Invalid CRC in response")
return response[1:-2]
def build_response(self, response_pdu):
"""Build the response"""
self._response_address = self._request_address
data = struct.pack(">B", self._response_address) + response_pdu
crc = struct.pack(">H", utils.calculate_crc(data))
return data + crc
def build_response(self, response_pdu):
"""Build the response"""
self._response_address = self._request_address
data = struct.pack(">B", self._response_address) + response_pdu
crc = struct.pack(">H", utils.calculate_crc(data))
return data + crc
