Best practice for connect and close of async client

[heinehenning]

Hi all,

I am currently building a modbus client with the AsyncModbusTcpClient.

The examples work very well. But I wonder, is it best practice to open and close the connection on every polling operation, like shown in the examples:

async def run_async_client(client, modbus_calls=None):
    """Run sync client."""
    _logger.info("### Client starting")
    await client.connect()
    assert client.connected
    if modbus_calls:
        await modbus_calls(client)
    client.close()
    _logger.info("### End of Program")

I thought it would be better to open the connection once and close the connection at a later point whenever communcation should stop.

Would be great to get a hint how that could be implemented with the async client.

Thanks in advance!

[janiversen]

of course not, see e.g. client_calls.py.

You connect in the beginning and close when finished.

Actually the example says that, it's modbus_calls not modbus_call

I am not what sure hint you want the code is right there in the example,
1: create client
2: connect
3: run all the calls you want
4: close

[heinehenning]

Thanks @janiversen for your answer.
I think my problem was with asyncio. I tried to await for the client.close() method. And that always produced exceptions.
Closing the client without await works.

[janiversen]

Just read the documentation, that helps.

The documentation, as well as our examples, how to use and not to use close().