StartAsyncSerialServer doesn't work pymodbus version 3.2 #1434
Description
Discussed in #1433
Originally posted by dlmoffett March 13, 2023
Versions
- Python: 3.9
- OS: Windows
- Pymodbus: 3.2.0
- Modbus Hardware (if used): USB to RS458
Pymodbus Specific
- Server:
StartAsyncSerialServer
Description
StartAsyncSerialServer no longer actually starts the server.
Code and Logs
import asyncio
import logging
from pymodbus.framer.rtu_framer import ModbusRtuFramer
from pymodbus.server import StartAsyncSerialServer
logging.basicConfig(
format="[%(asctime)s] [%(levelname)s] [%(name)s] %(message)s",
datefmt="%Y-%m-%d %H:%M:%S %z",
level=logging.INFO,
)
log = logging.getLogger(__name__)
async def modbus_slave():
return await StartAsyncSerialServer(
framer=ModbusRtuFramer,
port="COM10",
baudrate=19200,
)
def sanity():
log.info(f"✅ Here I am!")
asyncio.run(modbus_slave())
log.info(f"❌ I'm going insane!")Per the example documentation I would expect to only see my first log statement and for the server to be up and running indefinitely until I send a keyboard interrupt.
However, that's not the case and I see the following output when running the above code, which exits immediately after making the logs:
[2023-03-13 16:07:53 -0600] [INFO] [fix_pymodbus.sanity] ✅ Here I am!
[2023-03-13 16:07:53 -0600] [INFO] [fix_pymodbus.sanity] ❌ I'm going insane!
Working Monkey Patch
If I make the following monkey patch everything works as expected:
async def StartAsyncSerialServer( # pylint: disable=invalid-name,dangerous-default-value
context=None,
identity=None,
custom_functions=[],
**kwargs,
): # pragma: no cover
"""Start and run a serial modbus server.
:param context: The ModbusServerContext datastore
:param identity: An optional identify structure
:param custom_functions: An optional list of custom function classes
supported by server instance.
:param kwargs: The rest
"""
server = ModbusSerialServer(
context, kwargs.pop("framer", ModbusAsciiFramer), identity=identity, **kwargs
)
await server.start() # <----------------------Adding this makes it work 🤔
await _serverList.run(server, custom_functions)Expected Behavior
I expect the sample code above to to run until a keyboard interrupt.