Unit ID of MODBUS response is ignored?

[azuo_lee]

Go to the Modbus Connection settings. Is the checkbox "Permanent connection" checked?
Change the state of this checkbox. Then try again.

Yes, "Permanent connection" is checked. If I uncheck it and try again, as of now, this error has not occurred.
P.S: But "Alternative URL or IP" will no longer work with the option unckecked.

I want to check it, but id is not so easy.

Is it possible to utilize the Transaction ID? Generate a unique transaction ID for each request, and cache the request until it is timed out. Whenever a response is received, look for a cached request with the same transaction ID, if found and their Unit IDs also match, process the response and complete the request, otherwise, discard the response.