Version v3.8.5 is now available.

[janiversen]

Forgot 2 important bugs in v3.8.4, sorry for that:

• client requests always returns a response (with no_response or dev_id=0, ExceptionResponse is returned)
• Mark new simulator datastore as WIP, in the hope nobody starts using it except for commenting on the future.

[MrWaloo]

client requests always returns a response (with no_response or dev_id=0, ExceptionResponse is returned)

In the changelog of version 3.7.1 there was

Slave=0 will return first response, used to identify device address. (#2298)

also V3.7.4

Add no_response_expected argument to requests (#2385)

I haven't tested this new version yet, but it seems that it is not possible any more to request anything from devices with device_id = 0, which is (wrongly but still) the fact for numbers of inverters.
device_id = 0 should be used for broadcast only, but there are devices with device_id = 0. This is not my personnal choice, but this is a fact.

In doc/source/client.rst
we can read

:mod:slave=0 is defined as broadcast in the modbus standard, but pymodbus treats it as a normal device.

--> Not sure this was a bug.

imho dev_id = 0 should be possible

[janiversen]

I tend to agree, but fact is that the async client returned None and the sync client exceptionresponse now at least the always return exception response.

Do you have an actual device that only responds to dev_id 0 or are you merely seeing it theoretically? can you give me a reference to a manual please.

Please remember if a device really uses dev_id=0 it cannot be used on a normal serial line...I think the real fact is that many uses dev_id=0 because they only have one device and it is simpler but wrong.

[janiversen]

Please see issue #2571 for followup.

[MrWaloo]

I have replied in the linked Issue.