diff --git a/doc/source/examples.rst b/doc/source/examples.rst
index 2be001006..d7f249aa9 100644
--- a/doc/source/examples.rst
+++ b/doc/source/examples.rst
@@ -79,11 +79,11 @@ Source: :github:`examples/client_calls.py`
     :noindex:
 
 
-Client custom message
-^^^^^^^^^^^^^^^^^^^^^
-Source: :github:`examples/client_custom_msg.py`
+Custom message
+^^^^^^^^^^^^^^
+Source: :github:`examples/custom_msg.py`
 
-.. automodule:: examples.client_custom_msg
+.. automodule:: examples.custom_msg
     :undoc-members:
     :noindex:
 
diff --git a/examples/client_custom_msg.py b/examples/custom_msg.py
similarity index 79%
rename from examples/client_custom_msg.py
rename to examples/custom_msg.py
index a3dbf97a9..df64a3474 100755
--- a/examples/client_custom_msg.py
+++ b/examples/custom_msg.py
@@ -15,9 +15,15 @@
 
 from pymodbus import FramerType
 from pymodbus.client import AsyncModbusTcpClient as ModbusClient
+from pymodbus.datastore import (
+    ModbusSequentialDataBlock,
+    ModbusServerContext,
+    ModbusSlaveContext,
+)
 from pymodbus.exceptions import ModbusIOException
-from pymodbus.pdu import ExceptionResponse, ModbusPDU
+from pymodbus.pdu import ModbusPDU
 from pymodbus.pdu.bit_message import ReadCoilsRequest
+from pymodbus.server import ServerAsyncStop, StartAsyncTcpServer
 
 
 # --------------------------------------------------------------------------- #
@@ -31,7 +37,7 @@
 # --------------------------------------------------------------------------- #
 
 
-class CustomModbusPDU(ModbusPDU):
+class CustomModbusResponse(ModbusPDU):
     """Custom modbus response."""
 
     function_code = 55
@@ -73,7 +79,7 @@ def __init__(self, address=None, slave=1, transaction=0):
         """Initialize."""
         super().__init__(dev_id=slave, transaction_id=transaction)
         self.address = address
-        self.count = 16
+        self.count = 2
 
     def encode(self):
         """Encode."""
@@ -83,14 +89,10 @@ def decode(self, data):
         """Decode."""
         self.address, self.count = struct.unpack(">HH", data)
 
-    def execute(self, context):
+    async def update_datastore(self, context: ModbusSlaveContext) -> ModbusPDU:
         """Execute."""
-        if not 1 <= self.count <= 0x7D0:
-            return ExceptionResponse(self.function_code, ExceptionResponse.ILLEGAL_VALUE)
-        if not context.validate(self.function_code, self.address, self.count):
-            return ExceptionResponse(self.function_code, ExceptionResponse.ILLEGAL_ADDRESS)
-        values = context.getValues(self.function_code, self.address, self.count)
-        return CustomModbusPDU(values)
+        _ = context
+        return CustomModbusResponse()
 
 
 # --------------------------------------------------------------------------- #
@@ -119,14 +121,25 @@ def __init__(self, address, slave=1, transaction=0):
 
 async def main(host="localhost", port=5020):
     """Run versions of read coil."""
+    store = ModbusServerContext(slaves=ModbusSlaveContext(
+            di=ModbusSequentialDataBlock(0, [17] * 100),
+            co=ModbusSequentialDataBlock(0, [17] * 100),
+            hr=ModbusSequentialDataBlock(0, [17] * 100),
+            ir=ModbusSequentialDataBlock(0, [17] * 100),
+        ),
+        single=True
+    )
+    task = asyncio.create_task(StartAsyncTcpServer(
+        context=store,
+        address=(host, port),
+        custom_functions=[CustomRequest])
+    )
+    await asyncio.sleep(0.1)
     async with ModbusClient(host=host, port=port, framer=FramerType.SOCKET) as client:
         await client.connect()
 
-        # create a response object to control it works
-        CustomModbusPDU()
-
-        # new modbus function code.
-        client.register(CustomModbusPDU)
+        # add new modbus function code.
+        client.register(CustomModbusResponse)
         slave=1
         request1 = CustomRequest(32, slave=slave)
         try:
@@ -140,6 +153,9 @@ async def main(host="localhost", port=5020):
         request2 = Read16CoilsRequest(32, slave)
         result = await client.execute(False, request2)
         print(result)
+    await ServerAsyncStop()
+    task.cancel()
+    await task
 
 
 if __name__ == "__main__":
diff --git a/test/examples/test_examples.py b/test/examples/test_examples.py
index 446190a75..f78dfd7c2 100755
--- a/test/examples/test_examples.py
+++ b/test/examples/test_examples.py
@@ -15,8 +15,8 @@
 from examples.client_async_calls import main as main_client_async_calls
 from examples.client_calls import main as main_client_calls
 from examples.client_calls import template_call
-from examples.client_custom_msg import main as main_custom_client
 from examples.client_payload import main as main_payload_calls
+from examples.custom_msg import main as main_custom_client
 from examples.datastore_simulator_share import main as main_datastore_simulator_share
 from examples.message_parser import main as main_parse_messages
 from examples.server_async import setup_server
@@ -149,13 +149,11 @@ async def test_client_calls_errors(self, mock_server):
             await run_async_client(client, modbus_calls=template_call)
         client.close()
 
-    async def test_custom_msg(
-        self, mock_server, use_comm, use_framer, use_port, use_host
-    ):
+    async def test_custom_msg(self, use_comm, use_port, use_framer, use_host):
         """Test client with custom message."""
-        if use_comm != "tcp" or use_framer != "socket":
+        _ = use_framer
+        if use_comm != "tcp":
             return
-        assert mock_server
         await main_custom_client(port=use_port, host=use_host)
 
     async def test_payload(self, mock_clc, mock_cls):