diff --git a/umodbus/functions.py b/umodbus/functions.py
index b6251fe..7ae969e 100644
--- a/umodbus/functions.py
+++ b/umodbus/functions.py
@@ -278,8 +278,8 @@ def request_pdu(self):
         return struct.pack('>BHH', self.function_code, self.starting_address,
                            self.quantity)
 
-    @staticmethod
-    def create_from_request_pdu(pdu):
+    @classmethod
+    def create_from_request_pdu(cls, pdu):
         """ Create instance from request PDU.
 
         :param pdu: A request PDU.
@@ -287,7 +287,7 @@ def create_from_request_pdu(pdu):
         """
         _, starting_address, quantity = struct.unpack('>BHH', pdu)
 
-        instance = ReadCoils()
+        instance = cls()
         instance.starting_address = starting_address
         instance.quantity = quantity
 
@@ -324,8 +324,8 @@ def create_response_pdu(self, data):
         fmt = '>BB' + self.format_character * len(bytes_)
         return struct.pack(fmt, self.function_code, len(bytes_), *bytes_)
 
-    @staticmethod
-    def create_from_response_pdu(resp_pdu, req_pdu):
+    @classmethod
+    def create_from_response_pdu(cls, resp_pdu, req_pdu):
         """ Create instance from response PDU.
 
         Response PDU is required together with the quantity of coils read.
@@ -334,7 +334,7 @@ def create_from_response_pdu(resp_pdu, req_pdu):
         :param quantity: Number of coils read.
         :return: Instance of :class:`ReadCoils`.
         """
-        read_coils = ReadCoils()
+        read_coils = cls()
         read_coils.quantity = struct.unpack('>H', req_pdu[-2:])[0]
         byte_count = struct.unpack('>B', resp_pdu[1:2])[0]
 
@@ -360,7 +360,7 @@ def execute(self, slave_id, route_map):
         """ Execute the Modbus function registered for a route.
 
         :param slave_id: Slave id.
-        :param eindpoint: Instance of modbus.route.Map.
+        :param route_map: Instance of modbus.route.Map.
         :return: Result of call to endpoint.
         """
         try:
@@ -491,8 +491,8 @@ def request_pdu(self):
         return struct.pack('>BHH', self.function_code, self.starting_address,
                            self.quantity)
 
-    @staticmethod
-    def create_from_request_pdu(pdu):
+    @classmethod
+    def create_from_request_pdu(cls, pdu):
         """ Create instance from request PDU.
 
         :param pdu: A request PDU.
@@ -500,7 +500,7 @@ def create_from_request_pdu(pdu):
         """
         _, starting_address, quantity = struct.unpack('>BHH', pdu)
 
-        instance = ReadDiscreteInputs()
+        instance = cls()
         instance.starting_address = starting_address
         instance.quantity = quantity
 
@@ -537,8 +537,8 @@ def create_response_pdu(self, data):
         fmt = '>BB' + self.format_character * len(bytes_)
         return struct.pack(fmt, self.function_code, len(bytes_), *bytes_)
 
-    @staticmethod
-    def create_from_response_pdu(resp_pdu, req_pdu):
+    @classmethod
+    def create_from_response_pdu(cls, resp_pdu, req_pdu):
         """ Create instance from response PDU.
 
         Response PDU is required together with the quantity of inputs read.
@@ -547,7 +547,7 @@ def create_from_response_pdu(resp_pdu, req_pdu):
         :param quantity: Number of inputs read.
         :return: Instance of :class:`ReadDiscreteInputs`.
         """
-        read_discrete_inputs = ReadDiscreteInputs()
+        read_discrete_inputs = cls()
         read_discrete_inputs.quantity = struct.unpack('>H', req_pdu[-2:])[0]
         byte_count = struct.unpack('>B', resp_pdu[1:2])[0]
 
@@ -573,7 +573,7 @@ def execute(self, slave_id, route_map):
         """ Execute the Modbus function registered for a route.
 
         :param slave_id: Slave id.
-        :param eindpoint: Instance of modbus.route.Map.
+        :param route_map: Instance of modbus.route.Map.
         :return: Result of call to endpoint.
         """
         try:
@@ -695,16 +695,16 @@ def request_pdu(self):
         return struct.pack('>BHH', self.function_code, self.starting_address,
                            self.quantity)
 
-    @staticmethod
-    def create_from_request_pdu(pdu):
-
+    @classmethod
+    def create_from_request_pdu(cls, pdu):
         """ Create instance from request PDU.
+
         :param pdu: A request PDU.
         :return: Instance of this class.
         """
         _, starting_address, quantity = struct.unpack('>BHH', pdu)
 
-        instance = ReadHoldingRegisters()
+        instance = cls()
         instance.starting_address = starting_address
         instance.quantity = quantity
 
@@ -729,8 +729,8 @@ def create_response_pdu(self, data):
 
         return struct.pack(fmt, self.function_code, len(data) * 2, *data)
 
-    @staticmethod
-    def create_from_response_pdu(resp_pdu, req_pdu):
+    @classmethod
+    def create_from_response_pdu(cls, resp_pdu, req_pdu):
         """ Create instance from response PDU.
 
         Response PDU is required together with the number of registers read.
@@ -739,7 +739,7 @@ def create_from_response_pdu(resp_pdu, req_pdu):
         :param quantity: Number of coils read.
         :return: Instance of :class:`ReadCoils`.
         """
-        read_holding_registers = ReadHoldingRegisters()
+        read_holding_registers = cls()
         read_holding_registers.quantity = struct.unpack('>H', req_pdu[-2:])[0]
         read_holding_registers.byte_count = \
             struct.unpack('>B', resp_pdu[1:2])[0]
@@ -753,7 +753,7 @@ def execute(self, slave_id, route_map):
         """ Execute the Modbus function registered for a route.
 
         :param slave_id: Slave id.
-        :param eindpoint: Instance of modbus.route.Map.
+        :param route_map: Instance of modbus.route.Map.
         :return: Result of call to endpoint.
         """
         try:
@@ -875,8 +875,8 @@ def request_pdu(self):
         return struct.pack('>BHH', self.function_code, self.starting_address,
                            self.quantity)
 
-    @staticmethod
-    def create_from_request_pdu(pdu):
+    @classmethod
+    def create_from_request_pdu(cls, pdu):
         """ Create instance from request PDU.
 
         :param pdu: A request PDU.
@@ -884,7 +884,7 @@ def create_from_request_pdu(pdu):
         """
         _, starting_address, quantity = struct.unpack('>BHH', pdu)
 
-        instance = ReadInputRegisters()
+        instance = cls()
         instance.starting_address = starting_address
         instance.quantity = quantity
 
@@ -909,8 +909,8 @@ def create_response_pdu(self, data):
 
         return struct.pack(fmt, self.function_code, len(data) * 2, *data)
 
-    @staticmethod
-    def create_from_response_pdu(resp_pdu, req_pdu):
+    @classmethod
+    def create_from_response_pdu(cls, resp_pdu, req_pdu):
         """ Create instance from response PDU.
 
         Response PDU is required together with the number of registers read.
@@ -919,7 +919,7 @@ def create_from_response_pdu(resp_pdu, req_pdu):
         :param quantity: Number of coils read.
         :return: Instance of :class:`ReadCoils`.
         """
-        read_input_registers = ReadInputRegisters()
+        read_input_registers = cls()
         read_input_registers.quantity = struct.unpack('>H', req_pdu[-2:])[0]
 
         fmt = '>' + (conf.TYPE_CHAR * read_input_registers.quantity)
@@ -931,7 +931,7 @@ def execute(self, slave_id, route_map):
         """ Execute the Modbus function registered for a route.
 
         :param slave_id: Slave id.
-        :param eindpoint: Instance of modbus.route.Map.
+        :param route_map: Instance of modbus.route.Map.
         :return: Result of call to endpoint.
         """
         try:
@@ -1044,17 +1044,18 @@ def request_pdu(self):
         return struct.pack('>BHH', self.function_code, self.address,
                            self._value)
 
-    @staticmethod
-    def create_from_request_pdu(pdu):
+    @classmethod
+    def create_from_request_pdu(cls, pdu):
         """ Create instance from request PDU.
 
         :param pdu: A response PDU.
+        :return: Instance of this class.
         """
         _, address, value = struct.unpack('>BHH', pdu)
 
         value = 1 if value == 0xFF00 else value
 
-        instance = WriteSingleCoil()
+        instance = cls()
         instance.address = address
         instance.value = value
 
@@ -1077,14 +1078,14 @@ def create_response_pdu(self):
         fmt = '>BHH'
         return struct.pack(fmt, self.function_code, self.address, self._value)
 
-    @staticmethod
-    def create_from_response_pdu(resp_pdu):
+    @classmethod
+    def create_from_response_pdu(cls, resp_pdu):
         """ Create instance from response PDU.
 
         :param resp_pdu: Byte array with request PDU.
         :return: Instance of :class:`WriteSingleCoil`.
         """
-        write_single_coil = WriteSingleCoil()
+        write_single_coil = cls()
 
         address, value = struct.unpack('>HH', resp_pdu[1:5])
         value = 1 if value == 0xFF00 else value
@@ -1098,7 +1099,7 @@ def execute(self, slave_id, route_map):
         """ Execute the Modbus function registered for a route.
 
         :param slave_id: Slave id.
-        :param eindpoint: Instance of modbus.route.Map.
+        :param route_map: Instance of modbus.route.Map.
         """
         endpoint = route_map.match(slave_id, self.function_code, self.address)
         try:
@@ -1195,16 +1196,17 @@ def request_pdu(self):
         return struct.pack('>BH' + conf.TYPE_CHAR, self.function_code,
                            self.address, self.value)
 
-    @staticmethod
-    def create_from_request_pdu(pdu):
+    @classmethod
+    def create_from_request_pdu(cls, pdu):
         """ Create instance from request PDU.
 
-        :param pdu: A response PDU.
+        :param pdu: A request PDU.
+        :return: Instance of this class.
         """
         _, address, value = \
             struct.unpack('>BH' + conf.MULTI_BIT_VALUE_FORMAT_CHARACTER, pdu)
 
-        instance = WriteSingleRegister()
+        instance = cls()
         instance.address = address
         instance.value = value
 
@@ -1222,14 +1224,14 @@ def create_response_pdu(self):
         fmt = '>BH' + conf.TYPE_CHAR
         return struct.pack(fmt, self.function_code, self.address, self.value)
 
-    @staticmethod
-    def create_from_response_pdu(resp_pdu):
+    @classmethod
+    def create_from_response_pdu(cls, resp_pdu):
         """ Create instance from response PDU.
 
         :param resp_pdu: Byte array with request PDU.
         :return: Instance of :class:`WriteSingleRegister`.
         """
-        write_single_register = WriteSingleRegister()
+        write_single_register = cls()
 
         address, value = struct.unpack('>H' + conf.TYPE_CHAR, resp_pdu[1:5])
 
@@ -1242,7 +1244,7 @@ def execute(self, slave_id, route_map):
         """ Execute the Modbus function registered for a route.
 
         :param slave_id: Slave id.
-        :param eindpoint: Instance of modbus.route.Map.
+        :param route_map: Instance of modbus.route.Map.
         """
         endpoint = route_map.match(slave_id, self.function_code, self.address)
         try:
@@ -1348,8 +1350,8 @@ def request_pdu(self):
                            len(self.values), (len(self.values) // 8) + 1,
                            *bytes_)
 
-    @staticmethod
-    def create_from_request_pdu(pdu):
+    @classmethod
+    def create_from_request_pdu(cls, pdu):
         """ Create instance from request PDU.
 
         This method requires some clarification regarding the unpacking of
@@ -1416,7 +1418,7 @@ def create_from_request_pdu(pdu):
             # and reverse the list.
             res = res + [int(i) for i in fmt.format(value)][::-1]
 
-        instance = WriteMultipleCoils()
+        instance = cls()
         instance.starting_address = starting_address
         instance.quantity = quantity
 
@@ -1441,9 +1443,9 @@ def create_response_pdu(self):
         return struct.pack('>BHH', self.function_code, self.starting_address,
                            len(self.values))
 
-    @staticmethod
-    def create_from_response_pdu(resp_pdu):
-        write_multiple_coils = WriteMultipleCoils()
+    @classmethod
+    def create_from_response_pdu(cls, resp_pdu):
+        write_multiple_coils = cls()
 
         starting_address, data = struct.unpack('>HH', resp_pdu[1:5])
 
@@ -1456,7 +1458,7 @@ def execute(self, slave_id, route_map):
         """ Execute the Modbus function registered for a route.
 
         :param slave_id: Slave id.
-        :param eindpoint: Instance of modbus.route.Map.
+        :param route_map: Instance of modbus.route.Map.
         """
         for index, value in enumerate(self.values):
             address = self.starting_address + index
@@ -1554,8 +1556,8 @@ def request_pdu(self):
                            len(self.values), len(self.values) * 2,
                            *self.values)
 
-    @staticmethod
-    def create_from_request_pdu(pdu):
+    @classmethod
+    def create_from_request_pdu(cls, pdu):
         """ Create instance from request PDU.
 
         :param pdu: A request PDU.
@@ -1570,7 +1572,7 @@ def create_from_request_pdu(pdu):
 
         values = list(struct.unpack(fmt, pdu[6:]))
 
-        instance = WriteMultipleRegisters()
+        instance = cls()
         instance.starting_address = starting_address
         instance.values = values
 
@@ -1593,9 +1595,9 @@ def create_response_pdu(self):
         return struct.pack('>BHH', self.function_code, self.starting_address,
                            len(self.values))
 
-    @staticmethod
-    def create_from_response_pdu(resp_pdu):
-        write_multiple_registers = WriteMultipleRegisters()
+    @classmethod
+    def create_from_response_pdu(cls, resp_pdu):
+        write_multiple_registers = cls()
 
         starting_address, data = struct.unpack('>HH', resp_pdu[1:5])
 
@@ -1608,7 +1610,7 @@ def execute(self, slave_id, route_map):
         """ Execute the Modbus function registered for a route.
 
         :param slave_id: Slave id.
-        :param eindpoint: Instance of modbus.route.Map.
+        :param route_map: Instance of modbus.route.Map.
         """
         for index, value in enumerate(self.values):
             address = self.starting_address + index