AsyncModbusTcpClient defer_start doesn't seem to work anymore

[albireox]

Versions

• Python: 3.10
• OS: macOS 13.4
• Pymodbus: 3.2.2
• Modbus Hardware (if used): N/A

Pymodbus Specific

• Server: tcp - async
• Client: tcp - async

Description

It seems the option defer_start=True in AsyncModbusTcpClient is not honoured anymore in Pymodbus 3.2.2 (I think it was working in 3.1.x). Regardless of whether defer_start is True or False, the function will block once it's awaited. In itself, removing defer_start, that's not necessarily a showstopper, and code can be adapted to work with it, but this breaks a lot of code and it's a bit annoying that this breaking change was made in a minor release.

[janiversen]

If I remember right it also is no longer documented. We do not support defer_start, if you want that you need to instantiate the class e.g. ModbusTcpServer, and do whatever task handling you want.

[janiversen]

I can see we still have a couple of references, so lets keep this open until all is removed

[janiversen]

The change is documented in https://github.com/pymodbus-dev/pymodbus/blob/dev/API_changes.rst#version-320
so it should not come as a surprise.