Works ?

pymodbus/transport/serialtransport.py

@@ -9,10 +9,11 @@
 with contextlib.suppress(ImportError):
     import serial
 
+
 class SerialTransport(asyncio.Transport):
     """An asyncio serial transport."""
 
-    force_poll: bool
+    force_poll: bool = os.name == "nt"
 
     def __init__(self, loop, protocol, url, baudrate, bytesize, parity, stopbits, timeout) -> None:
         """Initialize."""
@@ -34,13 +35,7 @@ def setup(self) -> None:
             self.poll_task = asyncio.create_task(self.polling_task())
             self.poll_task.set_name("SerialTransport poll")
         else:
-            try:
-                self.async_loop.add_reader(self.sync_serial.fileno(), self.intern_read_ready)
-            except Exception as exc:
-                text = f"JAN setup --> os.name({os.name}) and {exc} force({self.force_poll})"
-                raise Exception(text)  # pylint: disable=raise-missing-from,broad-exception-raised
-
-
+            self.async_loop.add_reader(self.sync_serial.fileno(), self.intern_read_ready)
         self.async_loop.call_soon(self.intern_protocol.connection_made, self)
 
     def close(self, exc: Exception | None = None) -> None:
@@ -64,11 +59,7 @@ def write(self, data) -> None:
         """Write some data to the transport."""
         self.intern_write_buffer.append(data)
         if not self.force_poll:
-            try:
-                self.async_loop.add_writer(self.sync_serial.fileno(), self.intern_write_ready)
-            except Exception as exc:
-                text = f"JAN write --> os.name({os.name}) and {exc} force({self.force_poll})"
-                raise Exception(text)  # pylint: disable=raise-missing-from,broad-exception-raised
+            self.async_loop.add_writer(self.sync_serial.fileno(), self.intern_write_ready)
 
     def flush(self) -> None:
         """Clear output buffer and stops any more data being written."""
@@ -182,6 +173,3 @@ async def create_serial_connection(
                     timeout)
     loop.call_soon(transport.setup)
     return transport, protocol
-
-
-SerialTransport.force_poll = os.name == "nt"