diff --git a/API_changes.rst b/API_changes.rst
index 4ec98de3f..8c3fd1de8 100644
--- a/API_changes.rst
+++ b/API_changes.rst
@@ -11,6 +11,7 @@ API changes 3.7.0
 - on_connect_callback(true/false) added to async clients.
 - binary framer no longer supported
 - Framer.<type> renamed to FramerType.<type>
+- PDU classes moved to pymodbus/pdu
 
 
 API changes 3.6.0
diff --git a/doc/source/library/pymodbus.rst b/doc/source/library/pymodbus.rst
index 9875fd1ed..cdda34602 100644
--- a/doc/source/library/pymodbus.rst
+++ b/doc/source/library/pymodbus.rst
@@ -6,84 +6,87 @@ Extra functions
     :undoc-members:
     :show-inheritance:
 
-
-.. automodule:: pymodbus.bit_read_message
+.. automodule:: pymodbus.device
     :members:
     :undoc-members:
     :show-inheritance:
 
-.. automodule:: pymodbus.bit_write_message
+.. automodule:: pymodbus.events
     :members:
     :undoc-members:
     :show-inheritance:
 
-.. automodule:: pymodbus.device
+.. automodule:: pymodbus.exceptions
     :members:
     :undoc-members:
     :show-inheritance:
 
-.. automodule:: pymodbus.diag_message
+.. automodule:: pymodbus.factory
     :members:
     :undoc-members:
     :show-inheritance:
 
-.. automodule:: pymodbus.events
+.. automodule:: pymodbus.payload
     :members:
     :undoc-members:
     :show-inheritance:
 
-.. automodule:: pymodbus.exceptions
+.. automodule:: pymodbus.transaction
     :members:
     :undoc-members:
     :show-inheritance:
 
-.. automodule:: pymodbus.factory
+.. automodule:: pymodbus.utilities
     :members:
     :undoc-members:
     :show-inheritance:
 
-.. automodule:: pymodbus.file_message
+
+PDU classes
+===========
+
+.. automodule:: pymodbus.pdu.bit_read_message
     :members:
     :undoc-members:
     :show-inheritance:
 
-.. automodule:: pymodbus.mei_message
+.. automodule:: pymodbus.pdu.bit_write_message
     :members:
     :undoc-members:
     :show-inheritance:
 
-.. automodule:: pymodbus.other_message
+.. automodule:: pymodbus.pdu.diag_message
     :members:
     :undoc-members:
     :show-inheritance:
 
-.. automodule:: pymodbus.payload
+.. automodule:: pymodbus.pdu.file_message
     :members:
     :undoc-members:
     :show-inheritance:
 
-.. automodule:: pymodbus.pdu
+.. automodule:: pymodbus.pdu.mei_message
     :members:
     :undoc-members:
     :show-inheritance:
-    :noindex:
 
-.. automodule:: pymodbus.register_read_message
+.. automodule:: pymodbus.pdu.other_message
     :members:
     :undoc-members:
     :show-inheritance:
 
-.. automodule:: pymodbus.register_write_message
+.. automodule:: pymodbus.pdu.pdu
     :members:
     :undoc-members:
     :show-inheritance:
+    :noindex:
 
-.. automodule:: pymodbus.transaction
+.. automodule:: pymodbus.pdu.register_read_message
     :members:
     :undoc-members:
     :show-inheritance:
 
-.. automodule:: pymodbus.utilities
+.. automodule:: pymodbus.pdu.register_write_message
     :members:
     :undoc-members:
     :show-inheritance:
diff --git a/examples/client_custom_msg.py b/examples/client_custom_msg.py
index 01edf40f2..e4af4f4f1 100755
--- a/examples/client_custom_msg.py
+++ b/examples/client_custom_msg.py
@@ -14,9 +14,9 @@
 import struct
 
 from pymodbus import FramerType
-from pymodbus.bit_read_message import ReadCoilsRequest
 from pymodbus.client import AsyncModbusTcpClient as ModbusClient
 from pymodbus.pdu import ModbusExceptions, ModbusRequest, ModbusResponse
+from pymodbus.pdu.bit_read_message import ReadCoilsRequest
 
 
 # --------------------------------------------------------------------------- #
diff --git a/examples/message_generator.py b/examples/message_generator.py
index eaf7f036e..cf885b36c 100755
--- a/examples/message_generator.py
+++ b/examples/message_generator.py
@@ -4,14 +4,14 @@
 import codecs as c
 import logging
 
-import pymodbus.bit_read_message as modbus_bit
-import pymodbus.bit_write_message as modbus_bit_write
-import pymodbus.diag_message as modbus_diag
-import pymodbus.file_message as modbus_file
-import pymodbus.mei_message as modbus_mei
-import pymodbus.other_message as modbus_other
-import pymodbus.register_read_message as modbus_register
-import pymodbus.register_write_message as modbus_register_write
+import pymodbus.pdu.bit_read_message as modbus_bit
+import pymodbus.pdu.bit_write_message as modbus_bit_write
+import pymodbus.pdu.diag_message as modbus_diag
+import pymodbus.pdu.file_message as modbus_file
+import pymodbus.pdu.mei_message as modbus_mei
+import pymodbus.pdu.other_message as modbus_other
+import pymodbus.pdu.register_read_message as modbus_register
+import pymodbus.pdu.register_write_message as modbus_register_write
 from pymodbus.transaction import (
     ModbusAsciiFramer,
     ModbusRtuFramer,
diff --git a/pymodbus/client/mixin.py b/pymodbus/client/mixin.py
index f686761aa..bb5346d25 100644
--- a/pymodbus/client/mixin.py
+++ b/pymodbus/client/mixin.py
@@ -5,14 +5,14 @@
 from enum import Enum
 from typing import Any, Generic, TypeVar
 
-import pymodbus.bit_read_message as pdu_bit_read
-import pymodbus.bit_write_message as pdu_bit_write
-import pymodbus.diag_message as pdu_diag
-import pymodbus.file_message as pdu_file_msg
-import pymodbus.mei_message as pdu_mei
-import pymodbus.other_message as pdu_other_msg
-import pymodbus.register_read_message as pdu_reg_read
-import pymodbus.register_write_message as pdu_req_write
+import pymodbus.pdu.bit_read_message as pdu_bit_read
+import pymodbus.pdu.bit_write_message as pdu_bit_write
+import pymodbus.pdu.diag_message as pdu_diag
+import pymodbus.pdu.file_message as pdu_file_msg
+import pymodbus.pdu.mei_message as pdu_mei
+import pymodbus.pdu.other_message as pdu_other_msg
+import pymodbus.pdu.register_read_message as pdu_reg_read
+import pymodbus.pdu.register_write_message as pdu_req_write
 from pymodbus.exceptions import ModbusException
 from pymodbus.pdu import ModbusRequest
 
diff --git a/pymodbus/factory.py b/pymodbus/factory.py
index c351fa687..50302b50c 100644
--- a/pymodbus/factory.py
+++ b/pymodbus/factory.py
@@ -12,17 +12,17 @@
 # pylint: disable=missing-type-doc
 from collections.abc import Callable
 
-from pymodbus import bit_read_message as bit_r_msg
-from pymodbus import bit_write_message as bit_w_msg
-from pymodbus import diag_message as diag_msg
-from pymodbus import file_message as file_msg
-from pymodbus import mei_message as mei_msg
-from pymodbus import other_message as o_msg
-from pymodbus import pdu
-from pymodbus import register_read_message as reg_r_msg
-from pymodbus import register_write_message as reg_w_msg
 from pymodbus.exceptions import MessageRegisterException, ModbusException
 from pymodbus.logging import Log
+from pymodbus.pdu import bit_read_message as bit_r_msg
+from pymodbus.pdu import bit_write_message as bit_w_msg
+from pymodbus.pdu import diag_message as diag_msg
+from pymodbus.pdu import file_message as file_msg
+from pymodbus.pdu import mei_message as mei_msg
+from pymodbus.pdu import other_message as o_msg
+from pymodbus.pdu import pdu
+from pymodbus.pdu import register_read_message as reg_r_msg
+from pymodbus.pdu import register_write_message as reg_w_msg
 
 
 # --------------------------------------------------------------------------- #
diff --git a/pymodbus/pdu/__init__.py b/pymodbus/pdu/__init__.py
new file mode 100644
index 000000000..da3d86f8f
--- /dev/null
+++ b/pymodbus/pdu/__init__.py
@@ -0,0 +1,18 @@
+"""Framer."""
+__all__ = [
+    "ExceptionResponse",
+    "IllegalFunctionRequest",
+    "ModbusExceptions",
+    "ModbusPDU",
+    "ModbusRequest",
+    "ModbusResponse",
+]
+
+from pymodbus.pdu.pdu import (
+    ExceptionResponse,
+    IllegalFunctionRequest,
+    ModbusExceptions,
+    ModbusPDU,
+    ModbusRequest,
+    ModbusResponse,
+)
diff --git a/pymodbus/bit_read_message.py b/pymodbus/pdu/bit_read_message.py
similarity index 100%
rename from pymodbus/bit_read_message.py
rename to pymodbus/pdu/bit_read_message.py
diff --git a/pymodbus/bit_write_message.py b/pymodbus/pdu/bit_write_message.py
similarity index 100%
rename from pymodbus/bit_write_message.py
rename to pymodbus/pdu/bit_write_message.py
diff --git a/pymodbus/diag_message.py b/pymodbus/pdu/diag_message.py
similarity index 100%
rename from pymodbus/diag_message.py
rename to pymodbus/pdu/diag_message.py
diff --git a/pymodbus/file_message.py b/pymodbus/pdu/file_message.py
similarity index 100%
rename from pymodbus/file_message.py
rename to pymodbus/pdu/file_message.py
diff --git a/pymodbus/mei_message.py b/pymodbus/pdu/mei_message.py
similarity index 100%
rename from pymodbus/mei_message.py
rename to pymodbus/pdu/mei_message.py
diff --git a/pymodbus/other_message.py b/pymodbus/pdu/other_message.py
similarity index 100%
rename from pymodbus/other_message.py
rename to pymodbus/pdu/other_message.py
diff --git a/pymodbus/pdu.py b/pymodbus/pdu/pdu.py
similarity index 100%
rename from pymodbus/pdu.py
rename to pymodbus/pdu/pdu.py
diff --git a/pymodbus/register_read_message.py b/pymodbus/pdu/register_read_message.py
similarity index 100%
rename from pymodbus/register_read_message.py
rename to pymodbus/pdu/register_read_message.py
diff --git a/pymodbus/register_write_message.py b/pymodbus/pdu/register_write_message.py
similarity index 100%
rename from pymodbus/register_write_message.py
rename to pymodbus/pdu/register_write_message.py
diff --git a/test/framers/generator.py b/test/framers/generator.py
index 038f0d2b6..04344a823 100755
--- a/test/framers/generator.py
+++ b/test/framers/generator.py
@@ -9,7 +9,7 @@
     ModbusTlsFramer,
 )
 from pymodbus.pdu import ModbusExceptions as merror
-from pymodbus.register_read_message import (
+from pymodbus.pdu.register_read_message import (
     ReadHoldingRegistersRequest,
     ReadHoldingRegistersResponse,
 )
diff --git a/test/framers/test_old_framers.py b/test/framers/test_old_framers.py
index 6d6aa3e68..7101137fa 100644
--- a/test/framers/test_old_framers.py
+++ b/test/framers/test_old_framers.py
@@ -4,7 +4,6 @@
 import pytest
 
 from pymodbus import FramerType
-from pymodbus.bit_read_message import ReadCoilsRequest
 from pymodbus.client.base import ModbusBaseClient
 from pymodbus.exceptions import ModbusIOException
 from pymodbus.factory import ClientDecoder
@@ -14,6 +13,7 @@
     ModbusSocketFramer,
     ModbusTlsFramer,
 )
+from pymodbus.pdu.bit_read_message import ReadCoilsRequest
 from pymodbus.transport import CommType
 from pymodbus.utilities import ModbusTransactionState
 
diff --git a/test/sub_client/test_client.py b/test/sub_client/test_client.py
index 40fc0e86f..b853e8ab0 100755
--- a/test/sub_client/test_client.py
+++ b/test/sub_client/test_client.py
@@ -6,14 +6,14 @@
 
 import pytest
 
-import pymodbus.bit_read_message as pdu_bit_read
-import pymodbus.bit_write_message as pdu_bit_write
 import pymodbus.client as lib_client
-import pymodbus.diag_message as pdu_diag
-import pymodbus.file_message as pdu_file_msg
-import pymodbus.other_message as pdu_other_msg
-import pymodbus.register_read_message as pdu_reg_read
-import pymodbus.register_write_message as pdu_req_write
+import pymodbus.pdu.bit_read_message as pdu_bit_read
+import pymodbus.pdu.bit_write_message as pdu_bit_write
+import pymodbus.pdu.diag_message as pdu_diag
+import pymodbus.pdu.file_message as pdu_file_msg
+import pymodbus.pdu.other_message as pdu_other_msg
+import pymodbus.pdu.register_read_message as pdu_reg_read
+import pymodbus.pdu.register_write_message as pdu_req_write
 from examples.helper import get_certificate
 from pymodbus import FramerType
 from pymodbus.client.base import ModbusBaseClient
diff --git a/test/sub_function_codes/test_all_messages.py b/test/sub_function_codes/test_all_messages.py
index 2ab64d879..bfb669df9 100644
--- a/test/sub_function_codes/test_all_messages.py
+++ b/test/sub_function_codes/test_all_messages.py
@@ -1,17 +1,17 @@
 """Test all messages."""
-from pymodbus.bit_read_message import (
+from pymodbus.pdu.bit_read_message import (
     ReadCoilsRequest,
     ReadCoilsResponse,
     ReadDiscreteInputsRequest,
     ReadDiscreteInputsResponse,
 )
-from pymodbus.bit_write_message import (
+from pymodbus.pdu.bit_write_message import (
     WriteMultipleCoilsRequest,
     WriteMultipleCoilsResponse,
     WriteSingleCoilRequest,
     WriteSingleCoilResponse,
 )
-from pymodbus.register_read_message import (
+from pymodbus.pdu.register_read_message import (
     ReadHoldingRegistersRequest,
     ReadHoldingRegistersResponse,
     ReadInputRegistersRequest,
@@ -19,7 +19,7 @@
     ReadWriteMultipleRegistersRequest,
     ReadWriteMultipleRegistersResponse,
 )
-from pymodbus.register_write_message import (
+from pymodbus.pdu.register_write_message import (
     WriteMultipleRegistersRequest,
     WriteMultipleRegistersResponse,
     WriteSingleRegisterRequest,
diff --git a/test/sub_function_codes/test_bit_read_messages.py b/test/sub_function_codes/test_bit_read_messages.py
index 21817d0d7..5d190f023 100644
--- a/test/sub_function_codes/test_bit_read_messages.py
+++ b/test/sub_function_codes/test_bit_read_messages.py
@@ -9,13 +9,13 @@
 import struct
 from test.conftest import MockContext
 
-from pymodbus.bit_read_message import (
+from pymodbus.pdu import ModbusExceptions
+from pymodbus.pdu.bit_read_message import (
     ReadBitsRequestBase,
     ReadBitsResponseBase,
     ReadCoilsRequest,
     ReadDiscreteInputsRequest,
 )
-from pymodbus.pdu import ModbusExceptions
 
 
 res = [True] * 21
diff --git a/test/sub_function_codes/test_bit_write_messages.py b/test/sub_function_codes/test_bit_write_messages.py
index 7552cd4e5..94e2066f8 100644
--- a/test/sub_function_codes/test_bit_write_messages.py
+++ b/test/sub_function_codes/test_bit_write_messages.py
@@ -8,13 +8,13 @@
 """
 from test.conftest import FakeList, MockContext
 
-from pymodbus.bit_write_message import (
+from pymodbus.pdu import ModbusExceptions
+from pymodbus.pdu.bit_write_message import (
     WriteMultipleCoilsRequest,
     WriteMultipleCoilsResponse,
     WriteSingleCoilRequest,
     WriteSingleCoilResponse,
 )
-from pymodbus.pdu import ModbusExceptions
 
 
 # ---------------------------------------------------------------------------#
diff --git a/test/sub_function_codes/test_diag_messages.py b/test/sub_function_codes/test_diag_messages.py
index 5db301894..673222c93 100644
--- a/test/sub_function_codes/test_diag_messages.py
+++ b/test/sub_function_codes/test_diag_messages.py
@@ -2,7 +2,8 @@
 import pytest
 
 from pymodbus.constants import ModbusPlusOperation
-from pymodbus.diag_message import (
+from pymodbus.exceptions import NotImplementedException
+from pymodbus.pdu.diag_message import (
     ChangeAsciiInputDelimiterRequest,
     ChangeAsciiInputDelimiterResponse,
     ClearCountersRequest,
@@ -42,7 +43,6 @@
     ReturnSlaveNoResponseCountRequest,
     ReturnSlaveNoResponseCountResponse,
 )
-from pymodbus.exceptions import NotImplementedException
 
 
 class TestDataStore:
diff --git a/test/sub_function_codes/test_mei_messages.py b/test/sub_function_codes/test_mei_messages.py
index b0db6111a..d553e3461 100644
--- a/test/sub_function_codes/test_mei_messages.py
+++ b/test/sub_function_codes/test_mei_messages.py
@@ -7,7 +7,7 @@
 
 from pymodbus.constants import DeviceInformation
 from pymodbus.device import ModbusControlBlock
-from pymodbus.mei_message import (
+from pymodbus.pdu.mei_message import (
     ReadDeviceInformationRequest,
     ReadDeviceInformationResponse,
 )
diff --git a/test/sub_function_codes/test_other_messages.py b/test/sub_function_codes/test_other_messages.py
index 5b87c8154..eb43ad21e 100644
--- a/test/sub_function_codes/test_other_messages.py
+++ b/test/sub_function_codes/test_other_messages.py
@@ -1,7 +1,7 @@
 """Test other messages."""
 from unittest import mock
 
-import pymodbus.other_message as pymodbus_message
+import pymodbus.pdu.other_message as pymodbus_message
 
 
 class TestOtherMessage:
@@ -86,7 +86,7 @@ def test_get_comm_event_log_with_events(self):
 
     def test_report_slave_id_request(self):
         """Test report slave id request."""
-        with mock.patch("pymodbus.other_message.DeviceInformationFactory") as dif:
+        with mock.patch("pymodbus.pdu.other_message.DeviceInformationFactory") as dif:
             # First test regular identity strings
             identity = {
                 0x00: "VN",  # VendorName
@@ -126,7 +126,7 @@ def test_report_slave_id_request(self):
 
     def test_report_slave_id(self):
         """Test report slave id."""
-        with mock.patch("pymodbus.other_message.DeviceInformationFactory") as dif:
+        with mock.patch("pymodbus.pdu.other_message.DeviceInformationFactory") as dif:
             dif.get.return_value = {}
             request = pymodbus_message.ReportSlaveIdRequest()
             request.decode(b"\x12")
diff --git a/test/sub_function_codes/test_register_read_messages.py b/test/sub_function_codes/test_register_read_messages.py
index dcb1ef6c5..6b0072c21 100644
--- a/test/sub_function_codes/test_register_read_messages.py
+++ b/test/sub_function_codes/test_register_read_messages.py
@@ -2,7 +2,7 @@
 from test.conftest import FakeList, MockContext
 
 from pymodbus.pdu import ModbusExceptions
-from pymodbus.register_read_message import (
+from pymodbus.pdu.register_read_message import (
     ReadHoldingRegistersRequest,
     ReadHoldingRegistersResponse,
     ReadInputRegistersRequest,
diff --git a/test/sub_function_codes/test_register_write_messages.py b/test/sub_function_codes/test_register_write_messages.py
index 2327d090b..e89e97802 100644
--- a/test/sub_function_codes/test_register_write_messages.py
+++ b/test/sub_function_codes/test_register_write_messages.py
@@ -3,7 +3,7 @@
 
 from pymodbus.payload import BinaryPayloadBuilder, Endian
 from pymodbus.pdu import ModbusExceptions
-from pymodbus.register_write_message import (
+from pymodbus.pdu.register_write_message import (
     MaskWriteRegisterRequest,
     MaskWriteRegisterResponse,
     WriteMultipleRegistersRequest,
diff --git a/test/sub_server/test_server_asyncio.py b/test/sub_server/test_server_asyncio.py
index 34c16616b..e3de50956 100755
--- a/test/sub_server/test_server_asyncio.py
+++ b/test/sub_server/test_server_asyncio.py
@@ -266,7 +266,7 @@ async def test_async_tcp_server_modbus_error(self):
         BasicClient.data = TEST_DATA
         await self.start_server()
         with mock.patch(
-            "pymodbus.register_read_message.ReadHoldingRegistersRequest.execute",
+            "pymodbus.pdu.register_read_message.ReadHoldingRegistersRequest.execute",
             side_effect=NoSuchSlaveException,
         ):
             await self.connect_server()
diff --git a/test/test_file_message.py b/test/test_file_message.py
index ee71ba1ac..e210f6bcb 100644
--- a/test/test_file_message.py
+++ b/test/test_file_message.py
@@ -8,7 +8,8 @@
 """
 from test.conftest import MockContext
 
-from pymodbus.file_message import (
+from pymodbus.pdu import ModbusExceptions
+from pymodbus.pdu.file_message import (
     FileRecord,
     ReadFifoQueueRequest,
     ReadFifoQueueResponse,
@@ -17,7 +18,6 @@
     WriteFileRecordRequest,
     WriteFileRecordResponse,
 )
-from pymodbus.pdu import ModbusExceptions
 
 
 TEST_MESSAGE = b"\x00\n\x00\x08\x00\x01\x00\x02\x00\x03\x00\x04"
diff --git a/test/test_remote_datastore.py b/test/test_remote_datastore.py
index 1f59c62b8..b12d792d4 100644
--- a/test/test_remote_datastore.py
+++ b/test/test_remote_datastore.py
@@ -3,12 +3,12 @@
 
 import pytest
 
-from pymodbus.bit_read_message import ReadCoilsResponse
-from pymodbus.bit_write_message import WriteMultipleCoilsResponse
 from pymodbus.datastore.remote import RemoteSlaveContext
 from pymodbus.exceptions import NotImplementedException
 from pymodbus.pdu import ExceptionResponse
-from pymodbus.register_read_message import ReadInputRegistersResponse
+from pymodbus.pdu.bit_read_message import ReadCoilsResponse
+from pymodbus.pdu.bit_write_message import WriteMultipleCoilsResponse
+from pymodbus.pdu.register_read_message import ReadInputRegistersResponse
 
 
 class TestRemoteDataStore: